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Mild hyperthermia at 39-43 °C for 30-60 min is applied locoregionally to improve the oxygenation status of recurrent breast cancers, thus enhancing the efficacy of radio-, chemo-, and immunotherapy. In this context, estimated (or even conflicting) data are often used in computational modelling of tumour oxygenation and simulation of O 2 transport. In this chapter, we present information that may help to improve adjuvant thermotherapy delivered immediately prior to radiotherapy of recurrent breast cancers. Data are preferentially derived from clinical investigations; in some cases, measurements in experimental breast cancers are included.The biophysical properties presented for healthy, mostly postmenopausal, human breast (composite glandular-adipose-fibrous tissue) measured under normothermic (NT) conditions and in therapeutically heated breast cancers include tissue water content and tissue density. In general, averaged values of parameters reported for NT conditions are higher in breast cancers than in normal breast tissue, i.e., all ratios breast cancer/normal breast are >1. Mean values observed in breast cancers during mild hyperthermia (mHT) are consistently higher than those in NT tumours. Parameters determining convective transports in healthy breast tissue and breast cancer include blood flow rates, blood volume, exchanging water space, arterio-venous shunt flow, interstitial fluid flow rate, interstitial fluid pressure, microvascular permeability, interstitial hydraulic conductivity, and interstitial flow velocity. In general, averaged values of parameters measured under NT conditions are higher in breast cancers than in healthy breast. Except for interstitial fluid pressure, these values increase upon mHT treatment of cancers. Prime factors determining and describing the oxygenation status of the healthy breast, and in NT- versus mHT-treated breast cancers, include: oxygen (O 2 ) delivery rates, O 2 - extractions, O 2 - consumption rates, subepidermal microvascular HbO 2 , tissue oxygen solubility, oxygen diffusion coefficients, mean O 2 partial pressures pO 2 , hypoxic fractions HF <5 mmHg, oxygen enhancement ratio, and mitochondrial ROS production. With the exception of the mean pO 2 , O 2 extraction rate and tissue O 2 saturation all parameters listed are distinctly higher in breast cancers under NT conditions compared to normal breast. Mild hyperthermia results in therapeutically relevant improvements of the oxygenation status of cancers and enhances mitochondrial ROS production, thus improving radiosensitivity. Note: The oxygenation status of the healthy (postmenopausal) breast is very similar to that of the normal human subcutis., (© 2024. Oxygen Transport to Tissue International.)

On the occasion of ISOTT's half-century, in this chapter, tumour hypoxia (i.e. critically reduced oxygen levels on macro- and microscopic scales), recently classified as an additional hallmark of cancer, its various aetiology-related classifications (diffusion- or perfusion-limitations, hypoxaemic), time-frames of exposure (acute, chronic, cyclic), and different levels (moderate, mild, severe) within and across tumours, and its Janus-face-like role ("dichotomy") in tumour regression (e.g. apoptosis, necrosis) versus "adaptive" tumour progression have been updated and summarised. This latter knowledge is, to a great extent, based on (a) direct, reliable assessments and mapping of the heterogeneous tumour oxygenation status using minimally invasive polarographic pO 2 microsensors in clinical settings since the late 1980s, and (b) the discovery of the hypoxia-inducible factors (HIFs) in the early 1990s. These data have clarified the role of hypoxia in stimulating a variety of biologic responses that mediate cancer progression through changes (a) in the genome (associated with clonal selection and expansion), (b) in the transcriptome, and (c) in the proteome, as well as its role as a barrier to the effectiveness of anti-cancer therapies., (© 2024. Oxygen Transport to Tissue International.)

Measuring oxygen (O 2 ) in tissues has been a central theme of the International Society on Oxygen Transport to Tissue (ISOTT) since its founding 50 years ago in 1973. The initial presentations by many distinguished members reflect this focus and demonstrate the importance of the contributions of the members of ISOTT. This paper considers their work and its legacy in the context of the continuing challenges of making meaningful measurements of O 2 in tissue. Because many technical, physiological, and pathophysiological factors are directly or implicitly involved in obtaining any measured value of O 2 in living tissues, interpretations of what the measured value represents and its biological implications need to take these factors into account. The challenges arise from two very simple but painfully true factors that make it challenging to obtain measurements of O 2 in tissues in vivo that are useful for the understanding of physiological and pathophysiological processes. First, throughout the volume of functioning tissue that is assessed by any technique, there is a complex spatial heterogeneity of O 2 levels. No technique can usually fully represent this complexity in a given measurement, because the heterogeneity extends from the environment in the tissue surrounding cells to variations within the cell. Therefore, the value of the output from a measurement inevitably consists of a complex, averaged summary of O 2 in the tissue. Second, the levels of O 2 are constantly changing in living tissues (variations occur in seconds, minutes, hours, and/or days and differ by location) at rates that are difficult to resolve for available techniques, because they occur faster than data acquisition time and/or cannot be used as frequently as needed to follow the longer-term changes. However, as demonstrated in research reported in the publications from ISOTT, studies of O 2 in tissue, in spite of the potential ambiguities in the measured values, can provide very valuable insights into physiology and pathophysiology. This is most likely to occur if researchers explicitly recognise why and how their measurement does not fully portray the complexity of O 2 . When measurements can be repeated, the resulting change between measurements provides information about the dynamics of the physiology and pathophysiology. Assessing change in O 2 levels can also provide evidence about responses to treatments. Similarly, finding evidence of hypoxia, even though it does not capture the heterogeneity and dynamics actually happening in the tissue, can still inform clinical care if the measurement is well-understood., (© 2024. Oxygen Transport to Tissue International.)

Introduction: Breast cancer is globally the leading cancer in women, and despite the high 5-year survival rate the most frequent cause of cancer related deaths. Surgery, systemic therapy and radiotherapy are the three pillars of curative breast cancer treatment. However, locoregional recurrences frequently occur after initial treatment and are often challenging to treat, amongst others due to high doses of previous radiotherapy treatments. Radiotherapy can be combined with local hyperthermia to sensitize tumor cells to radiation and thereby significantly reduce the required radiation dose. Therefore, the combination treatment of mild local hyperthermia, i.e. locally heating of the tissue to 39-43°C, and re-irradiation with a reduced total dose is a relevant treatment option for previously irradiated patients. The mechanisms of this effect in the course of the therapy are to date not well understood and will be investigated in the HISTOTHERM study., Methods and Analyses: Patients with local or (loco)regional recurrent breast cancer with macroscopic tumors are included in the study. Local tumor control is evaluated clinically and histologically during the course of a combination treatment of 60 minutes mild superficial hyperthermia (39 - 43°C) using water-filtered infrared A (wIRA) irradiation, immediately followed by hypofractionated re-irradiation with a total dose of 20-24 Gy, administered in weekly doses of 4 Gy. Tumor and tumor stroma biopsies as well as blood samples will be collected prior to treatment, during therapy (at a dose of 12 Gy) and in the follow-up to monitor therapy response. The treatment represents the standard operating procedure for hyperthermia plus re-irradiation. Various tissue and blood-based markers are analyzed. We aim at pinpointing key mechanisms and markers for therapy response which may help guiding treatment decisions in future. In addition, quality of life in the course of treatment will be assessed and survival data will be evaluated., Registration: The study is registered at the German Clinical Trials Register, Deutsches Register Klinischer Studien (DRKS00029221)., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Thomsen, Sahlmann, Bronsert, Schilling, Poensgen, May, Timme-Bronsert, Grosu, Vaupel, Gebbers, Multhoff and Lüchtenborg.)

(1) Background: Mild hyperthermia (mHT, 39-42 °C) is a potent cancer treatment modality when delivered in conjunction with radiotherapy. mHT triggers a series of therapeutically relevant biological mechanisms, e.g., it can act as a radiosensitizer by improving tumor oxygenation, the latter generally believed to be the commensurate result of increased blood flow, and it can positively modulate protective anticancer immune responses. However, the extent and kinetics of tumor blood flow (TBF) changes and tumor oxygenation are variable during and after the application of mHT. The interpretation of these spatiotemporal heterogeneities is currently not yet fully clarified. (2) Aim and methods: We have undertaken a systematic literature review and herein provide a comprehensive insight into the potential impact of mHT on the clinical benefits of therapeutic modalities such as radio- and immuno-therapy. (3) Results: mHT-induced increases in TBF are multifactorial and differ both spatially and with time. In the short term , changes are preferentially caused by vasodilation of co-opted vessels and of upstream normal tissue vessels as well as by improved hemorheology. Sustained TBF increases are thought to result from a drastic reduction of interstitial pressure, thus restoring adequate perfusion pressures and/or HIF-1α- and VEGF-mediated activation of angiogenesis. The enhanced oxygenation is not only the result of mHT-increased TBF and, thus, oxygen availability but also of heat-induced higher O 2 diffusivities, acidosis- and heat-related enhanced O 2 unloading from red blood cells. (4) Conclusions: Enhancement of tumor oxygenation achieved by mHT cannot be fully explained by TBF changes alone. Instead, a series of additional, complexly linked physiological mechanisms are crucial for enhancing tumor oxygenation, almost doubling the initial O 2 tensions in tumors.

Purpose: The heating characteristics of water-filtered infrared-A (wIRA) radiation were investigated in vivo in two body regions of healthy humans according to the quality standards of the European Society for Hyperthermic Oncology (ESHO) using an irradiance (infrared-A) of 146 W m -2 as recommended for clinical superficial hyperthermia (HT)., Methods: wIRA was applied to the abdominal wall and lumbar region for 60 min. Skin surface temperature was limited to ≤43 °C. Tissue temperatures were measured invasively at 1-min intervals before, during and after wIRA exposure using five fiber-optical probes at depths of 1-20 mm., Results: Significant differences between body regions occurred during the heating-up phase at depths of 5-15 mm. Thermal steady states were reached at depths ≤5 mm after exposures of 5-6 min, and ≤20 mm after 20 min. On average, the minimum requirements of ESHO were exceeded in both regions by the following factors: ≈3 for the heating rate, ≈2 for the specific absorption rate and ≈1.4 for the temperature rise. Tissue depths with T 90  ≥ 40 °C and T 50  > 41 °C were ≤10 mm, and ≤20 mm for T max  ≤ 43 °C. The temperature decay time after termination of irradiation was 1-5 min. Corresponding temperatures were ≤42.2 °C for CEM 43 and ≤41.8 °C for CEM 43 T 90 , i.e., they are inadequate for direct thermal cell killing., Conclusions: Thermography-controlled wIRA-HT complies with the ESHO criteria for superficial HT as a radiosensitizer and avoids the risk of thermal skin toxicity.

The aim of this review is to stimulate readers to undertake appropriate investigations of the mechanism for a possible oxygen effect in FLASH. FLASH is a method of delivery of radiation that empirically, in animal models, appears to decrease the impact of radiation on normal tissues while retaining full effect on tumors. This has the potential for achieving a significantly increased effectiveness of radiation therapy. The mechanism is not known but, especially in view of the prominent role that oxygen has in the effects of radiation, investigations of mechanisms of FLASH have often focused on impacts of FLASH on oxygen levels. We and others have previously shown that simple differential depletion of oxygen directly changing the response to radiation is not a likely mechanism. In this review we consider how time-varying changes in oxygen levels could account for the FLASH effect by changing oxygen-dependent signaling in cells. While the methods of delivering FLASH are still evolving, current approaches for FLASH can differ from conventional irradiation in several ways that can impact the pattern of oxygen consumption: the rate of delivery of the radiation (40 Gy/s vs. 0.1 Gy/s), the time over which each fraction is delivered (e.g., <0.5 s. vs. 300 s), the delivery in pulses, the number of fractions, the size of the fractions, and the total duration of treatment. Taking these differences into account and recognizing that cell signaling is an intrinsic component of the need for cells to maintain steady-state conditions and, therefore, is activated by small changes in the environment, we delineate the potential time dependent changes in oxygen consumption and overview the cell signaling pathways whose differential activation by FLASH could account for the observed biological effects of FLASH. We speculate that the most likely pathways are those involved in repair of damaged DNA., (© 2023. The Author(s), under exclusive license to Springer Nature Switzerland AG.)

Cancers are complex, heterogeneous, dynamic and aggressive diseases exhibiting a series of characteristic biophysical traits which complement the original biological hallmarks of cancers favouring progressive growth, metastasis, and contributing to immune evasion and treatment resistance. One of the prevalent differences between most solid tumors and their corresponding, healthy tissues is a significantly higher water content (hyperhydration) in cancers. As a consequence, cancers have distinctly higher (Fick's) diffusion coefficients D [cm 2  s -1 ] for the respiratory gases O 2 and CO 2 , the key substrate glucose, and for the oncometabolite lactate. In addition, cancers have (a) clearly increased specific heat capacities c p [J g -1  K -1 ], thus representing high-capacity-tissues upon therapeutic heating induced by electromagnetic irradiation, and (b) higher thermal conductivities k [W m -1  K -1 ], i.e., increased abilities to conduct heat. Therefore, in diffusion analyses (e.g., when describing critical O 2 and glucose supplies or CO 2 removal, and the development of hypoxic subvolumes) and for modeling temperature distributions in hyperthermia treatment planning, these specific cancer-related data must be considered in order to reliably reflect oncologic thermo-radiotherapy settings., (© 2023. The Author(s), under exclusive license to Springer Nature Switzerland AG.)

Hepatocellular carcinoma (HCC) is characterised by a robust resistance to therapy, resulting in the very poor prognosis usually seen in patients with unresectable HCC. A thorough understanding of the molecular and cellular pathogenesis of HCC is of paramount importance for the identification of more effective treatment options. As hypoxia in tumours is associated with the malignant phenotype, molecules involved in the hypoxic response are being investigated as potential targets for cancer therapy. One key hallmark of human HCC is the hypervascularisation and arterialisation of the tumour's blood supply. Hypoxia being a strong inducer of neo-angiogenesis, it was hypothesised over 20 years ago that reduced oxygen levels in human HCC are a crucial feature of this deadly disease. However, while there is a considerable body of literature espousing the presumed functional relevance of hypoxia in HCC, direct measurements of oxygen partial pressures or O 2 concentrations in human HCCs have yet to be performed. This narrative review seeks to demonstrate how overinterpretation of in vitro experiments and incorrect citations have resulted in HCCs being perceived as severely hypoxic tumours., Competing Interests: Conflict of interest The authors have no conflicts of interest to declare. Please refer to the accompanying ICMJE disclosure forms for further details., (Copyright © 2021 The Author(s). Published by Elsevier B.V. All rights reserved.)

Purpose: Intratumoral hypoxia increases resistance of head-and-neck squamous cell carcinoma (HNSCC) to radiotherapy. [ 18 F]FMISO PET imaging enables noninvasive hypoxia monitoring, though requiring complex logistical efforts. We investigated the role of plasma interleukin-6 (IL-6) as potential surrogate parameter for intratumoral hypoxia in HNSCC using [ 18 F]FMISO PET/CT as reference., Methods: Within a prospective trial, serial blood samples of 27 HNSCC patients undergoing definitive chemoradiation were collected to analyze plasma IL-6 levels. Intratumoral hypoxia was assessed in treatment weeks 0, 2, and 5 using [ 18 F]FMISO PET/CT imaging. The association between PET-based hypoxia and IL-6 was examined using Pearson's correlation and multiple regression analyses, and the diagnostic power of IL-6 for tumor hypoxia response prediction was determined with receiver-operating characteristic analyses., Results: Mean IL-6 concentrations were 15.1, 19.6, and 31.0 pg/mL at baseline, week 2 and week 5, respectively. Smoking (p=0.050) and reduced performance status (p=0.011) resulted in higher IL-6 levels, whereas tumor (p=0.427) and nodal stages (p=0.334), tumor localization (p=0.439), and HPV status (p=0.294) had no influence. IL-6 levels strongly correlated with the intratumoral hypoxic subvolume during treatment (baseline: r=0.775, p<0.001; week 2: r=0.553, p=0.007; week 5: r=0.734, p<0.001). IL-6 levels in week 2 were higher in patients with absent early tumor hypoxia response (p=0.016) and predicted early hypoxia response (AUC=0.822, p=0.031). Increased IL-6 levels at week 5 resulted in a trend towards reduced progression-free survival (p=0.078) and overall survival (p=0.013)., Conclusion: Plasma IL-6 is a promising surrogate marker for tumor hypoxia dynamics in HNSCC patients and may facilitate hypoxia-directed personalized radiotherapy concepts., Trial Registration: The prospective trial was registered in the German Clinical Trial Register (DRKS00003830). Registered 20 August 2015., (© 2021. The Author(s).)

Background: Tumor hypoxia worsens the prognosis of head-and-neck squamous cell carcinoma (HNSCC) patients, and plasma hypoxia markers may be used as biomarkers for radiotherapy personalization. We therefore investigated the role of the hypoxia-associated plasma proteins osteopontin, galectin-3, vascular endothelial growth factor (VEGF) and connective tissue growth factor (CTGF) as surrogate markers for imaging-based tumor hypoxia., Methods: Serial blood samples of HNSCC patients receiving chemoradiation within a prospective trial were analyzed for osteopontin, galectin-3, VEGF and CTGF concentrations. Tumor hypoxia was quantified in treatment weeks 0, 2 and 5 using [ 18 F]FMISO PET/CT. The association between PET-defined hypoxia and the plasma markers was determined using Pearson's correlation analyses. Receiver-operating characteristic analyses were conducted to reveal the diagnostic value of the hypoxia markers., Results: Baseline osteopontin (r = 0.579, p  < 0.01) and galectin-3 (r = 0.429, p  < 0.05) correlated with the hypoxic subvolume (HSV) prior to radiotherapy, whereas VEGF (r = 0.196, p =  0.36) and CTGF (r = 0.314, p =  0.12) showed no association. Patients with an HSV > 1 mL in week 2 exhibited increased VEGF ( p  < 0.05) and CTGF ( p  < 0.05) levels in week 5. Pretherapeutic osteopontin levels were higher in patients exhibiting residual hypoxia at the end of treatment (104.7 vs. 60.8 ng/mL , p  < 0.05) and could therefore predict residual hypoxia (AUC = 0.821, 95% CI 0.604-1.000, p  < 0.05)., Conclusion: In this exploratory analysis, osteopontin correlated with the initial HSV and with residual tumor hypoxia; therefore, there may be a rationale to study hypoxic modification based on osteopontin levels. However, as plasma hypoxia markers do not correspond to any spatial information of tumor hypoxia, they have limitations regarding the replacement of [ 18 F]FMISO PET-based focal treatments. The results need to be validated in larger patient cohorts to draw definitive conclusions., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2022 The Authors. Published by Elsevier B.V. on behalf of European Society for Radiotherapy and Oncology.)

Clinical trials have shown that mild hyperthermia (HT) serves as an adjunct to cancer treatments such as chemo- and radiotherapy. Recently, a high efficacy of mild HT immediately followed by hypofractionated radiotherapy (RT) in treatment of recurrent breast cancer has been documented if temperatures of 39-43 °C are achieved for 40-60 min. In the present study, temperature and oxygenation profiles were measured in superficial tissues of healthy volunteers exposed to water-filtered infrared-A- (wIRA)- irradiation, to verify that adequate thermal doses together with the improved tumor oxygenation necessary for radiosensitisation are obtained. Experiments were performed using a wIRA-system equipped with two wIRA-radiators, each with a thermography camera for real-time monitoring of the skin surface temperature. Temperatures within the abdominal wall were measured with fibre optic sensors at defined tissue depths (subepidermal, and 1-20 mm inside the tissue). The corresponding tissue pO 2 values were assessed with fluorometric microsensors. In selected situations, hyperspectral tissue imaging was used to visualise the oxygenation status of normal skin and superficial tumours in patients. Pre-treatment skin surface temperature was 34.6 °C. Upon wIRA exposure, average skin surface temperatures reached 41.6 °C within 5-12 min. Maximum tissue temperatures of 41.8 °C were found at a tissue depth of 1 mm, with a steady decline in deeper tissue layers (41.6 °C @ 5 mm, 40.8 °C @ 10 mm, 40.6 °C @ 15 mm, and 40.1 °C @ 20 mm). Effective HT levels ≥39 °C were established in tissue depths up to 25 mm. Tissue heating was accompanied by a significant increase in tissue pO 2 values [e.g., at a tissue depth of 13 mm mean pO 2 rose from 46 mmHg to 81 mmHg (@ T = 40.5 °C). In the post-heating phase (+ 5 min), pO 2 was 79 mmHg (@ T = 38 °C) and 15 min post-heat pO 2 was 72 mmHg (@ T = 36.8 °C)]. pO 2 values remained elevated for 30-60 min post-heat. Non-invasive monitoring of normal skin and of recurrent breast cancers confirmed the improved O 2 status by wIRA-HT. In conclusion, wIRA-irradiation enables effective tissue heating (T = 39-43 °C) associated with distinct increases in blood flow and pO 2 . These adjustments unequivocally meet the requirement for effective radiosensitisation., (© 2022. Springer Nature Switzerland AG.)

The delivery of radiation at an ultra-high dose rate (FLASH) is an important new approach to radiotherapy (RT) that appears to be able to improve the therapeutic ratio by diminishing damage to normal tissues. While the mechanisms by which FLASH improves outcomes have not been established, a role involving molecular oxygen (O 2 ) is frequently mentioned. In order to effectively determine if the protective effect of FLASH RT occurs via a differential direct depletion of O 2 (compared to conventional radiation), it is essential to consider the known role of O 2 in modifying the response of cells and tissues to ionising radiation (known as 'the oxygen effect'). Considerations include: (1) The pertinent reaction involves an unstable intermediate of radiation-damaged DNA, which either undergoes chemical repair to restore the DNA or reacts with O 2 , resulting in an unrepairable lesion in the DNA, (2) These reactions occur in the nuclear DNA, which can be used to estimate the distance needed for O 2 to diffuse through the cell to reach the intermediates, (3) The longest lifetime that the reactive site of the DNA is available to react with O 2 is 1-10 μsec, (4) Using these lifetime estimates and known diffusion rates in different cell media, the maximal distance that O 2 could travel in the cytosol to reach the site of the DNA (i.e., the nucleus) in time to react are 60-185 nm. This calculation defines the volume of oxygen that is pertinent for the direct oxygen effect, (5) Therefore, direct measurements of oxygen to determine if FLASH RT operates through differential radiochemical depletion of oxygen will require the ability to measure oxygen selectively in a sphere of <200 nm, with a time resolution of the duration of the delivery of FLASH, (6) It also is possible that alterations of oxygen levels by FLASH could occur more indirectly by affecting oxygen-dependent cell signalling and/or cellular repair., (© 2022. Springer Nature Switzerland AG.)

To maintain a multitude of vital functions, blood flow to the normal liver and the hepatic oxygenation status has to be kept on a high level (1.0-1.2 mL/g/min and 30-40 mmHg, respectively). There is a longitudinal oxygen partial pressure (pO 2 ) gradient within the liver sinusoids between periportal inflow and outflow into the central vein leading to a zonation of the O 2 status, which is associated with a zoning of liver functions. Oxygenation of metastatic lesions of colorectal cancers in the liver is poor due to a dysfunctional vascularity and inadequate blood supply. Hepatocellular carcinomas (HCCs) are highly vascularised (arterialised), metabolically very active and present with a predominantly arterial blood supply. HCCs are generally believed to be very hypoxic. However, confirmation of severe hypoxia based on reliable, direct pO 2 measurements in HCCs is still missing., (© 2022. Springer Nature Switzerland AG.)

Reliable measurements using modern techniques and consensus in experimental design have enabled the assessment of novel data sets for normal maternal and foetal respiratory physiology at term. These data sets include (a) principal factors affecting placental gas transfer, e.g., maternal blood flow through the intervillous space (IVS) (500 mL/min) and foeto-placental blood flow (480 mL/min), and (b) O 2 , CO 2 and pH levels in the materno-placental and foeto-placental circulation. According to these data, the foetus is adapted to hypoxaemic hypoxia. Despite flat oxygen partial pressure (pO 2 ) gradients between the blood of the IVS and the umbilical arteries of the foetus, adequate O 2 delivery to the foetus is maintained by the higher O 2 affinity of the foetal blood, high foetal haemoglobin (HbF) concentrations, the Bohr effect, the double-Bohr effect, and high foeto-placental (=umbilical) blood flow. Again, despite flat gradients, adequate CO 2 removal from the foetus is maintained by a high diffusion capacity, high foeto-placental blood flow, the Haldane effect, and the double-Haldane effect. Placental respiratory gas exchange is perfusion-limited, rather than diffusion-limited, i.e., O 2 uptake depends on O 2 delivery., (© 2022. Springer Nature Switzerland AG.)

Purpose: Tumor perfusion is considered to be the principal factor determining the build-up of therapeutically effective thermal fields. This assumes that malignancies have lower perfusions than their homologous tissues. This assumption, however, ignores the fact that several tumor types have higher perfusions than their healthy counterparts. Additionally, flow changes upon hyperthermia (39-43 °C) are non-predictable and extremely heterogeneous. Therefore, modeling temperature distribution further requires a more robust parameter, different in malignancies and healthy tissues, i.e., water content (C w ), which highly determines thermal properties upon electromagnetic irradiation., Method: Systematic literature reviews of C w and specific heat capacities (c p ) were conducted up to 28 February 2022, providing an updated, comprehensive data overview based on original manuscripts, reviews and databases., Results: C w - and c p -values of cancers and their corresponding healthy tissues are presented. Strong correlations between these two parameters are described. In general, malignant tumors have distinctly higher C w values than their homologous tissues. With increasing C w in low-water-content normal tissues (<70 wt.%), c p rises exponentially from 1.5 to 3.3 J·g -1 ·K -1 . In high-water-content normal tissues (≥70 wt.%), c p increases linearly from 3.5 to 3.8 J·g -1 ·K -1 . In malignant tumors (>80 wt.%), c p rises linearly from 3.6 to 3.9 J·g -1 ·K -1 . Cancers contain up to 27% more water than their tissues of origin and must be considered as 'high-capacitance-tissues'., Conclusions: Hyperhydration of cancers result in higher c p -values, causing cancers to be better heat reservoirs than corresponding normal tissues upon electromagnetic irradiation. Reliable, tissue-/cancer-specific c p values must be considered when modeling temperature distributions in hyperthermic treatment.

On 2 July 2021, Kronenfeld et al. [...].

Background: Radiation-associated angiosarcoma of the breast (RAASB) is a rare, challenging disease, with surgery being the accepted basic therapeutic approach. In contrast, the role of adjuvant and systemic therapies is a subject of some controversy. Local recurrence rates reported in the literature are mostly heterogeneous and are highly dependent on the extent of surgery. In cases of locally recurrent or unresectable RAASB, prognosis is very poor., Methods: We retrospectively report on 10 consecutive RAASB patients, most of them presenting with locally recurrent or unresectable RAASB, which were treated with thermography-controlled water-filtered infrared-A (wIRA) superficial hyperthermia (HT) immediately followed by re-irradiation (re-RT). Patients with RAASB were graded based on their tumor extent before onset of radiotherapy (RT)., Results: We recorded a local control (LC) rate dependent on tumor extent ranging from a high LC rate of 100% (two of two patients) in the adjuvant setting with an R0 or R2 resection to a limited LC rate of 33% (one of three patients) in patients with inoperable, macroscopic tumor lesions., Conclusion: Combined HT and re-RT should be considered as an option (a) for adjuvant treatment of RAASB, especially in cases with positive resection margins and after surgery of local recurrence (LR), and (b) for definitive treatment of unresectable RAASB.

Contrary to Warburg's original thesis, accelerated aerobic glycolysis is not a primary, permanent and universal consequence of dysfunctional or impaired mitochondria compensating for poor ATP yield per mole of glucose. Instead, in most tumours the Warburg effect is an essential part of a 'selfish' metabolic reprogramming, which results from the interplay between (normoxic/hypoxic) hypoxia-inducible factor-1 (HIF-1) overexpression, oncogene activation (cMyc, Ras), loss of function of tumour suppressors (mutant p53, mutant phosphatase and tensin homologue (PTEN), microRNAs and sirtuins with suppressor functions), activated (PI3K-Akt-mTORC1, Ras-Raf-MEK-ERK-cMyc, Jak-Stat3) or deactivated (LKB1-AMPK) signalling pathways, components of the tumour microenvironment, and HIF-1 cooperation with epigenetic mechanisms. Molecular and functional processes of the Warburg effect include: (a) considerable acceleration of glycolytic fluxes; (b) adequate ATP generation per unit time to maintain energy homeostasis and electrochemical gradients; (c) backup and diversion of glycolytic intermediates facilitating the biosynthesis of nucleotides, non-essential amino acids, lipids and hexosamines; (d) inhibition of pyruvate entry into mitochondria; (e) excessive formation and accumulation of lactate, which stimulates tumour growth and suppression of anti-tumour immunity - in addition, lactate can serve as an energy source for normoxic cancer cells and drives malignant progression and resistances to conventional therapies; (f) cytosolic lactate being mainly exported through upregulated lactate-proton symporters (MCT4), working together with other H + transporters, and carbonic anhydrases (CAII, CAIX), which hydrate CO 2 from oxidative metabolism to form H + and bicarbonate; (g) these proton export mechanisms, in concert with poor vascular drainage, being responsible for extracellular acidification, driving malignant progression and resistance to conventional therapies; (h) maintenance of the cellular redox homeostasis and low reactive oxygen species (ROS) formation; and (i) HIF-1 overexpression, mutant p53 and mutant PTEN, which inhibit mitochondrial biogenesis and functions, negatively impacting cellular respiration rate. The glycolytic switch is an early event in oncogenesis and primarily supports cell survival. All in all, the Warburg effect, i.e. aerobic glycolysis in the presence of oxygen and - in principle - functioning mitochondria, constitutes a major driver of the cancer progression machinery, resistance to conventional therapies, and poor patient outcome. However, as evidenced during the last two decades, in a minority of tumours primary mitochondrial defects can play a key role promoting the Warburg effect and tumour progression due to mutations in some Krebs cycle enzymes and mitochondrial ROS overproduction., (© 2020 The Authors. The Journal of Physiology published by John Wiley & Sons Ltd on behalf of The Physiological Society.)

Measuring molecular oxygen levels in vivo has been the cornerstone of understanding the effects of hypoxia in normal tissues and malignant tumors. Here we discuss the advances in a variety of partial pressure of oxygen ( P O 2 ) measurements and imaging techniques and relevant oxygen thresholds. A focus on electron paramagnetic resonance (EPR) imaging shows the validation of treating hypoxic tumours with a threshold of P O 2  ≤ 10 Torr, and demonstrates utility for in vivo oxygen imaging, as well as its current and future role in cancer studies., (© 2020 The Authors. The Journal of Physiology © 2020 The Physiological Society.)

Abundance and signaling of the epidermal growth factor receptor (EGFR) and programmed cell death protein ligand 1 (PD-L1) in head and neck squamous cell carcinoma (HNSCC) are not only genetically determined but are also subject to the traits of the tumor microenvironment, which has hitherto not been clarified completely. We investigated the impact of hypoxia on the EGFR system and on PD-L1 in six HPV negative HNSCC cell lines in vitro and in FaDu xenografts in vivo . Protein levels of EGFR, AKT, pAKT, ERK1/2, pERK1/2, CA IX, cleaved PARP (apoptosis), LC3B (autophagy), and PD-L1 were quantified by western blot after oxygen deprivation or CoCl 2 , staurosporine, and erlotinib treatment. In FaDu xenograft tumors the expression of EGFR, CA IX andCD34 staining were analyzed. Reduced oxygen supply strongly downregulated EGFR protein levels and signaling in FaDu cells in vitro and in vivo , and a transient downregulation of EGFR signaling was found in three other HNSCC cell lines. PD-L1 was affected by oxygen deprivation in only one HNSCC cell line showing increased protein amounts. The results of this study indicate a significant impact of the traits of the tumor microenvironment on crucial molecular targets of cancer therapies with high clinical relevance for therapy resistance and response in HNSCC., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Zahnreich, Gebrekidan, Multhoff, Vaupel, Schmidberger and Mayer.)

Contrary to Warburg's original thesis, accelerated aerobic glycolysis is not a primary and permanent consequence of dysfunctional mitochondria compensating for a poor ATP yield per mole glucose. Instead, the Warburg effect is an essential part of a "selfish" metabolic reprogramming, which results from the interplay between (normoxic or hypoxic) HIF-1 overexpression, oncogene activation (cMyc, Ras), loss of function of tumor suppressors (mutant p53, mutant PTEN, microRNAs and sirtuins with suppressor functions), activated (PI3K/Akt/mTORC1, Ras/Raf/Mek/Erk/c-Myc) or deactivated (AMPK) signaling pathways, components of the tumor microenvironment, and HIF-1 cooperations with epigenetic mechanisms. Molecular and functional processes of the Warburg effect include (a) considerably accelerated glycolytic fluxes; (b) adequate ATP generation per unit time to maintain energy homeostasis; (c) backup and diversion of glycolytic intermediates facilitating the biosynthesis of nucleotides, nonessential amino acids, lipids, and hexosamines; (d) inhibition of pyruvate entry into mitochondria; (e) excessive formation and accumulation of lactate which stimulates tumor growth and suppression of antitumor immunity (in addition, lactate can serve as an energy source for normoxic cancer cells, contributes to extracellular acidosis, and thus drives malignant progression and resistances to conventional therapies); (f) maintenance of the cellular redox homeostasis and low ROS formation; and (g) HIF-1 overexpression, mutant p53, and mutant PTEN which inhibit mitochondrial biogenesis and functions, thus negatively impacting cellular respiration rate. The glycolytic switch is an early event in oncogenesis and primarily supports cell survival. All in all, the Warburg effect, i.e., aerobic glycolysis in the presence of oxygen and - in principle - functioning mitochondria, constitutes a major driver of the cancer progression machinery, resistance to conventional therapies, and - finally - poor patient outcome.

Clinical measurements of O 2 in tissues will inevitably provide data that are at best aggregated and will not reflect the inherent heterogeneity of O 2 in tissues over space and time. Additionally, the nature of all existing techniques to measure O 2 results in complex sampling of the volume that is sensed by the technique. By recognizing these potential limitations of the measures, one can focus on the very important and useful information that can be obtained from these techniques, especially data about factors that can change levels of O 2 and then exploit these changes diagnostically and therapeutically. The clinical utility of such data ultimately needs to be verified by careful studies of outcomes related to the measured changes in levels of O 2 .

Following the introduction of immune checkpoint inhibitors, a substantial prolongation of the overall survival has been achieved for many patients with multiple brain metastases from melanoma. However, heterogeneity between individual tumor responses is incompletely understood. In order to determine the impact of the individual tumor phenotype on the prognosis of melanoma patients, we examined surgical sections from 33 patients who were treated with radiotherapy (whole-brain radiotherapy, WBRT, stereotactic radiotherapy, STX, or both) and Ipilimumab. We analyzed multiplex staining of the hypoxia marker GLUT-1, the adenosine (ADO)-associated enzymes CD73 and CD39, and CD8, a marker of cytotoxic T lymphocytes (CTL) on a single-cell basis using QuPath. Additionally, the MOSAIC interaction analysis algorithm was used to explore the hypothesis that CTL systematically avoid GLUT-1 high tumor areas. Our results revealed, that a strong GLUT-1 expression, low numbers of CTL, or exclusion of CTL from the tumor were correlated with significant prognostic detriment. Hypoxic tumors overall have smaller amounts of CTL, and spatial analysis revealed a repellent effect of hypoxia on CTL. In contrast to in vitro studies, specific upregulation of ADO-related enzymes CD73 and CD39 in GLUT-1 high tumor regions was never observed. In this study, we could show direct in vivo evidence for hypoxia-mediated immunosuppression in melanoma. Moreover, this study suggests a significant prognostic relevance of the tumor immune phenotype, the strength of CD8 infiltration in the tumor, and the expression of hypoxia marker GLUT-1 on melanoma cells. Last, our results suggest a temporal stability of the microenvironment-mediated immunosuppressive phenotype in melanoma.

It is well understood that the level of molecular oxygen (O 2 ) in tissue is a very important factor impacting both physiology and pathological processes as well as responsiveness to some treatments. Data on O 2 in tissue could be effectively utilized to enhance precision medicine. However, the nature of the data that can be obtained using existing clinically applicable techniques is often misunderstood, and this can confound the effective use of the information. Attempts to make clinical measurements of O 2 in tissues will inevitably provide data that are aggregated over time and space and therefore will not fully represent the inherent heterogeneity of O 2 in tissues. Additionally, the nature of existing techniques to measure O 2 may result in uneven sampling of the volume of interest and therefore may not provide accurate information on the "average" O 2 in the measured volume. By recognizing the potential limitations of the O 2 measurements, one can focus on the important and useful information that can be obtained from these techniques. The most valuable clinical characterizations of oxygen are likely to be derived from a series of measurements that provide data about factors that can change levels of O 2 , which then can be exploited both diagnostically and therapeutically. The clinical utility of such data ultimately needs to be verified by careful studies of outcomes related to the measured changes in levels of O 2 ., (© 2020 The Authors. Physiological Reports published by Wiley Periodicals LLC on behalf of The Physiological Society and the American Physiological Society.)

Purpose: The aim of this study was to investigate whether textural features of tumour hypoxia, assessed with serial [ 18 F]fluoromisonidazole (FMISO)-PET, were able to predict clinical outcome in patients with head and neck squamous cell carcinoma (HNSCC, T1-4, N+, M0) during chemoradiotherapy (CRT)., Methods: In a preliminary evaluation of a prospective trial, tumour hypoxia was evaluated in 29 patients via serial FMISO-PET before and during CRT. All patients received an initial [ 18 F]fluorodeoxyglucose (FDG)-PET before CRT, and tumour regions were defined on this FDG-PET. The first-order metrics tumour-to-background ratio (TBR mean , TBR max , TBR peak ), coefficient of variation, total lesion uptake and integral non-uniformity were calculated for all scans. Further, 3 second-order (textural) features from two grey-level matrices were calculated, as well as differential non-uniformity (u diff ). Prognostic value was examined by median split for group separation (GS) in Kaplan-Meier estimates and correlated with overall survival (OS), quantified via log-rank tests (p ≤ 0.05) and group-relative hazard ratios (HR)., Results: Within a median follow-up of 29.6 months (95% CI: 16.8-48.0 months), no first-order metrics predicted OS with a significant GS (all p > 0.05) on any FMISO-PET scan. Only u diff before and in week 2 during CRT (p = 0.03, HR = 10.8 and p = 0.05, HR = 5.2) and non-uniformity from grey-level run length matrix in week 2 separated prognostic groups (p = 0.05, HR = 5.3); lower values were correlated with better OS. Further, the decrease in u diff from before CRT to week 2 was correlated with better OS (p = 0.04, HR = 9.4). FDG-PET before CRT did not predict outcome in any measure., Conclusions: Textural features on FMISO-PET scans before CRT, in week 2 and, to a limited degree, the change of features during CRT, were able to identify head and neck squamous cell carcinoma patients with better OS, suggesting that a higher homogeneity of the degree of hypoxia in tumours could correlate with a better outcome after CRT.

Effective tumor control in patients suffering from unresectable locally recurrent breast cancer (LRBC) in pre-irradiated areas can be achieved by re-irradiation combined with superficial hyperthermia. Using this combined modality, total re-irradiation dose and toxicity can be significantly reduced compared to conventionally fractionated treatment schedules with total doses of 60-66 Gy. Applying contact-free, thermography-controlled water-filtered infrared-A superficial hyperthermia, immediately followed by hypofractionated re-irradiation, consisting of 4 Gy once per week up to a total dose of 20 Gy, resulted in high overall response rates even in large-sized tumors. Comparability of clinical data between different combined Hyperthermia (HT)/Radiotherapy (RT) treatment schedules is impeded by the highly individual characteristics of this disease. Tumor size, ranging from microscopic disease and small lesions to large-sized cancer en cuirasse, is described as one of the most important prognostic factors. However, in clinical studies and analyses of LRBC, tumor size has so far been reported in a very heterogeneous way. Therefore, we suggest a novel, simple and feasible size classification (rClasses 0-IV). Applying this classification for the evaluation of 201 patients with pre-irradiated LRBC allowed for a stratification into distinct prognostic groups.

Introduction : Lung cancer is a devastating disease with poor overall survival. Despite significant advances in the treatment of lung cancers using radiochemotherapy, targeted therapies and/or immune therapies prognosis remains poor. The capacity of natural killer (NK) cells to provide a first line of defense that can bridge and orchestrate innate and 'downstream' adaptive immune responses renders them to be an ideal platform on which to base new cancer therapeutics. Areas covered : We provide an overview of the mechanisms controlling the effector functions of NK cells, tumor-directed immune escape, the impact and influence of NK cells on the development of effective, protective anti-tumor immunity and the therapeutic potential of combined cytokine-, complement-dependent- and antibody-dependent cellular cytotoxicity (CDC/ADCC), NK-92-, KIR mismatch- and CAR-NK cell-based therapies. Expert opinion : Despite promising results of immuno-oncological approaches, a relevant proportion of patients do not profit from these therapies, partly due to an ineffective NK cell activation, a lack of tumor-specific NK cells, an upregulated expression of checkpoint pathways, and a low mutational burden, which hinders the development of long-term adaptive immunity. Strategies that re-activate NK cells in combination with other therapies are therefore likely to be beneficial for the clinical outcome of patients with lung cancer. Abbreviations: ADCC: antibody-dependent cell-mediated cytotoxicity; ALK: anaplastic lymphoma kinase; CAR: chimeric antigen receptor; CDC: complement-dependent cytotoxicity; CEACAM-1: carcinoembryonic antigen-related cell adhesion molecule 1; DC: dendritic cell; DNAM: activating, maturation receptor; EGFR, epidermal growth factor receptor; EMT: epithelial-to-mesenchymal transition; EpCAM: epithelial cell adhesion molecule; GM-CSF: granulocyte monocyte colony stimulating factor; HIF: hypoxia inducible factor; IDO, indoleamine 2,3-dioxygenase; IFN: interferon; IL: interleukin; ITIM/ITAM: immune tyrosine-based inhibitory/activatory motif; KIR: killer cell immunoglobulin-like receptor; LAG-3: lymphocyte activation gene 3; MDSC: myeloid derived suppressor cells; MICA/B: MHC class I-related proteins A/B; MHC: major histocompatibility complex; mTOR: mechanistic target of rapamycin; NCAM: neuronal adhesion molecule; NCR: natural cytotoxicity receptor; NK: natural killer; NSCLC: non-small cell lung cancer; PD-1: programmed cell death 1; PS: phosphatidylserine; SCLC: small cell lung cancer; STAT: signal transducer and activator of transcription; TAM: tumor-associated M2 macrophages; TCR: T cell receptor; TIGIT: T cell immunoglobulin and ITIM domain; Tim-3: T cell immunoglobulin- and mucin domain-containing 3; TNF: tumor necrosis factor; ULBP: UL16-binding protein.

Purpose: The quality assurance guidelines of the European Society for Hyperthermic Oncology (ESHO) specify the requirements for appropriate superficial heating using phantoms. In this current piglet study, we have examined these requirements under in vivo conditions., Materials and Methods: The evaluation is based on simultaneous, invasive temperature measurements at 8 different depths between 2 and 20 mm in the thigh of anesthetized piglets during irradiation with water-filtered infrared radiation (wIRA). Temperature probes were equally distributed in an area of 10 cm diameter of homogeneously irradiated skin. Piglets were irradiated to 126.5 mW cm -2 in the spectral range of IR-A., Results: Heating rates and specific absorption rates were in full accordance with the ESHO standards. Due to early onset of thermoregulation, the desired temperature rise of 6 K at a depth of 5 mm was achieved after about 10 min of exposure, i.e. 4 min later than required for phantoms. After reaching thermal steady state, on average T 90 ≥ 40 °C occurred in tissue depths up to 20 mm, T 50 ≥ 41 °C up to 16 mm, and a mean CEM 43 T 90 ≈ 1 min was calculated for depths up to 8 mm., Conclusions: Piglet data are comparable with preliminary literature data assessed in vivo in the abdominal wall and in recurrent breast cancer of humans. The potential of wIRA-HT for adequate treatment of superficial tissues/cancers in the clinical setting thus is confirmed. To ensure therapeutically needed doses of wIRA-HT, irradiation times should be extended.

The emergence of antibiotic-resistant bacteria in the last century is alarming and calls for alternative, nonchemical treatment strategies. Thermal medicine uses heat for the treatment of infectious diseases but its use in facultative and obligate intracellular bacteria remains poorly studied. In this review, we summarize previous research on reducing the infectious burden of Mycobacterium ulcerans and Chlamydia trachomatis by using water-filtered infrared A-radiation (wIRA), a special form of heat radiation with high tissue penetration and low thermal load on the skin surface. Mycobacterium ulcerans is a thermosensitive bacterium causing chronic necrotizing skin disease. Therefore, previous data on wIRA-induced improvement of wound healing and reduction of wound infections is summarized first. Then, pathogenesis and treatment of infections with M. ulcerans causing Buruli ulcer and of those with C. trachomatis infecting the ocular conjunctiva and resulting in blinding trachoma are discussed. Both bacteria cause neglected tropical diseases and have similar geographical distributions. Results of previous in vitro and in vivo studies using wIRA on M. ulcerans and C. trachomatis infections are presented. Finally, technical aspects of using wIRA in patients are critically reviewed and open questions driving future research are highlighted. In conclusion, wIRA is a promising tool for reducing infectious burden due to intracellular bacteria such as M. ulcerans and C. trachomatis .

Purpose: Hyperthermia demonstrated clinical efficacy in multimodal cancer treatment. Multipotent mesenchymal stromal cells (MSCs) as part of the tumor-supporting stroma modulate tumor response and tissue regeneration after hyperthermia. We aimed to investigate the effects of hyperthermia on the survival, stem cell characteristics and heat shock expression of human MSCs. Materials and methods: Human MSCs and normal human dermal fibroblasts (NHDFs) were exposed to temperatures between 37 °C and 44 °C for 60 min, and hyperthermic sensitivity was examined by clonogenicity, proliferation and viability assays. The influence of 42 °C hyperthermia on the MSCs' adhesion potential, migratory capacity, surface marker expression and multi-lineage differentiation capability was investigated. Cell cycle distribution, apoptosis and senescence after 42 °C hyperthermia were determined by flow cytometry and β-galactosidase staining. Heat shock protein expression was determined by Western Blots. Results: MSCs exhibited decreased clonogenic survival after 40 °C and 42 °C hyperthermia compared to NHDFs, while proliferative activity and viability were comparable after hyperthermia up to 44 °C. MSC adhesion was reduced after 42 °C hyperthermia, while the characteristic surface marker expression and the migratory ability remained unaffected in 42 °C hyperthermia-exposed MSCs. 42 °C hyperthermia diminished the adipogenic differential potential of all tested MSC samples. A pronounced G2/M arrest was found after 42 °C hyperthermia and was associated with increased apoptosis and senescence levels in MSCs. MSCs exhibited slightly lower heat shock protein levels compared to NHDFs. Conclusion: Human MSCs exhibit a thermosensitive phenotype which reduced the multipotent cells' regenerative abilities, resulting in impaired tissue regeneration after hyperthermia treatment or thermal injuries. On the other hand, tumor-associated MSCs may be efficiently targeted by hyperthermia treatment.

The aim of the paper is to discuss what currently is feasible clinically to measure the level of oxygen and how that measurement can be clinically useful. Because oxygen in tissues is quite heterogeneous and all methods of measurement can only provide an average across heterogeneities at some spatial and temporal resolution, the values that are obtained may have limitations on their clinical utility. However, even if such limitations are significant, if one utilizes repeated measurements and focuses on changes in the measured levels, rather than 'absolute levels', it may be possible to obtain very useful clinical information. While these considerations are especially pertinent in cancer, they also pertain to most other types of pathology.

The success of treatment for malignancies, especially those undergoing radiation therapy or chemotherapy, has long been recognized to depend on the degree of hypoxia in the tumor. In addition to the prognostic value of knowing the tumor's initial level of hypoxia, assessing the tumor oxygenation during standard therapy or oxygen-related treatments (such as breathing oxygen-enriched gas mixtures or taking drugs that can increase oxygen supply to tissues) can provide valuable data to improve the efficacy of treatments. A series of early clinical studies of tumors in humans are ongoing at Dartmouth and Emory using electron paramagnetic resonance (EPR) oximetry to assess tumor oxygenation, initially and over time during either natural disease progression or treatment. This approach has the potential for reaching the long-sought goal of enhancing the effectiveness of cancer therapy. In order to effectively reach this goal, we consider the validity of the practical and statistical assumptions when interpreting the measurements made in vivo for patients undergoing treatment for cancer.

Inhospitable conditions within the tumor microenvironment (TME) are a characteristic feature ('hallmark') of most solid malignancies. Regional tumor hypoxia is a primary deficiency since it plays a key role in malignant progression. Severe hypoxia is often associated with other detrimental conditions in the TME as a consequence of hypoxia-/HIF-1α-induced (with/without oncogene-direction and/or reciprocal interaction of cancer cells with TME cells) metabolic re-programming, exorbitant extracellular adenosine (ADO) generation and VEGF overexpression/VEGF-R activation. Re-programming of the tumor metabolism inter alia includes a 'selfish' upregulation of aerobic glycolysis/glycolytic flux ('Warburg effect'), a strongly enhanced glutaminolysis in tumor cells, ketogenesis in cancer-associated fibroblasts, and an acceleration of the tryptophan uptake/intensified catabolism yielding kynurenine, which can support the malignant phenotype. Aerobic glycolysis and glutaminolysis result in lactate accumulation (up to 40 mM), and together with the enhanced ketogenesis and CO 2 /carbonic acid production lead to extracellular acidosis (pH e  < 6.8). These traits of the TME individually or collectively operate towards cancer progression via e.g. promotion of genetic instability and mutation, resistance to apoptosis, clonal selection, limitless cell survival and sustained proliferation, continuous angiogenesis and tumor growth, local invasion and distant metastasis, anti-tumor immunosuppression and resistance to therapy.

Hypoxia, one of the hallmarks of cancer, is caused by an insufficient oxygen supply, mostly due to a chaotic, deficient tumor microcirculation. Apart from a hypoxia-mediated resistance to standard therapies, modulated gene and protein expression, genetic instability and malignant progression, hypoxia also plays a pivotal role in anti-cancer immune responses by (a) reducing survival, cytolytic and migratory activity of effector cells such as CD4 + cells, CD8 + cytotoxic T cells, natural killer-like T cells and natural killer cells, (b) reducing the production and release of effector cytokines, (c) supporting immunosuppressive cells such as regulatory T cells, myeloid-derived suppressor cells and M2 macrophages, (d) increasing the production and release of immunosuppressive cytokines, and (e) inducing the expression of immune checkpoint inhibitors. In this minireview, immunosuppressive effects of hypoxia- and HIF-1a-driven traits in cancers are described.

In the early 1920s, Warburg published experimental data on the enhanced conversion of glucose to pyruvate (followed by lactate formation) even in the presence of abundant oxygen (aerobic glycolysis, Warburg effect). He attributed this metabolic trait to a respiratory injury and considered this a universal metabolic alteration in carcinogenesis. This interpretation of the data was questioned since the early 1950s. Realistic causative mechanisms and consequences of the Warburg effect were described only during the past 15 years and are summarized in this article. There is clear evidence that mitochondria are not defective in most cancers. Aerobic glycolysis, a key metabolic feature of the Warburg phenotype, is caused by active metabolic reprogramming required to support sustained cancer cell proliferation and malignant progression. This metabolic switch is directed by altered growth factor signaling, hypoxic or normoxic activation of HIF-1α- transcription, oncogene activation or loss-of-function of suppressor genes, and is implemented in the hostile tumor microenvironment. The 'selfish' reprogramming includes (a) overexpression of glucose transporters and of key glycolytic enzymes, and an accelerated glycolytic flux with subsequent accumulation and diversion of glycolytic intermediates for cancer biomass synthesis, (b) high-speed ATP production that meets the energy demand, and (c) accumulation of lactate which drives tumor progression and largely contributes to tumor acidosis, which in turn synergistically favors tumor progression and resistance to certain antitumor therapies, and compromises antitumor immunity. Altogether, the Warburg effect is the central contributor to the cancer progression machinery.

Background: Membrane heat shock protein 70 (mHsp70) is indicative of high-risk tumors and serves as a tumor-specific target for natural killer (NK) cells stimulated with Hsp70 peptide (TKD) and Interleukin(IL)-2. Radiochemotherapy (RCT), mHsp70-targeting NK cells, and programmed death(PD)-1 inhibition were combined to improve the efficacy of tumor-specific immune cells in a non-small cell lung carcinoma (NSCLC) patient., Patient: Following simultaneous RCT (64.8 Gy), a patient with inoperable NSCLC (cT4, cN3, cM0, stage IIIb) was treated with 4 cycles of autologous ex vivo TKD/IL-2-activated NK cells and the PD-1 antibody nivolumab as a second-line therapy. Blood samples were taken for immunophenotyping during the course of therapy., Results: Adoptive transfer of ex vivo TKD/IL-2-activated NK cells after RCT combined with PD-1 blockade is well tolerated and results in superior overall survival (OS). No viable tumor cells but a massive immune cell infiltration in fibrotic tissue was detected after therapy. Neither tumor progression nor distant metastases were detectable by CT scanning 33 months after diagnosis. Therapy response was associated with significantly increased CD3 - /NKG2D + /CD94 + NK cell counts, elevated CD8 + to CD4 + T cell and CD3 - /CD56 bright to CD3 - /CD56 dim NK cell ratios, and significantly reduced regulatory T cells (Tregs) in the peripheral blood., Conclusion: A combined therapy consisting of RCT, mHsp70-targeting NK cells, and PD-1 antibody inhibition is well tolerated, induces anti-tumor immunity, and results in long-term tumor control in one patient with advanced NSCLC. Further, randomized studies are necessary to confirm the efficacy of this combination therapy.

Purpose: The temporal and spatial formation of the temperature field and its changes during/upon water-filtered infrared-A (wIRA)-irradiation in porcine skin and subcutis were investigated in vivo in order to get a detailed physical basis for thermotherapy of superficial tumors and infections caused by thermosensitive microbial pathogens (e.g., Mycobacterium ulcerans causing Buruli ulcer). Methods: Local wIRA-hyperthermia was performed in 11 anesthetized piglets using 85.0 mW cm -2 , 103.2 mW cm -2 and 126.5 mW cm -2 , respectively. Invasive temperature measurements were carried out simultaneously in 1-min intervals using eight fiber-optical probes at different tissue depths between 2 and 20 mm, and by an IR thermometer at the skin surface. Results: Tissue temperature distribution depended on incident irradiance, exposure time, tissue depths and individual 'physiologies' of the animals. Temperature maxima were found at depths between 4 and 7 mm, exceeding skin surface temperatures by about 1-2 K. Tissue temperatures above 37 °C, necessary to eradicate M. ulcerans at depths <20 mm, were reached reliably. Conclusions: wIRA-hyperthermia may be considered as a novel therapeutic option for treatment of local skin infections caused by thermosensitive pathogens (e.g., in Buruli ulcer). To ensure temperatures required for heat treatment of superficial tumors deeper than 4 mm, the incident irradiance needed can be controlled either by (a) invasive temperature measurements or (b) control of skin surface temperature and considering possible temperature increases up to 1-2 K in underlying tissue.

The metabolic tumor microenvironment (TME) is characterized inter alia by critical oxygen depletion (hypoxia/anoxia), extracellular acidosis (pH ≤ 6.8), high lactate levels (up to 40 mM in heterogeneously distributed areas), strongly elevated adenosine concentrations (10-100 μM) and declining nutrient resources. These TME features are major drivers, e.g., for genetic instability, intratumor heterogeneity, malignant progression and development of resistance to conventional anticancer therapies. In this context, hypoxia-dependent (and non-hypoxic) HIF-1α activation plays a key role in orchestrating a multifaceted (local) suppression of innate and adaptive antitumor immune responses (and of immune-based tumor treatment). Besides the characteristic traits mentioned, the immune-suppressive actions can additionally be triggered by an (over-)expression of VEGF and activation of VEGFR, and externalisation of phosphatidylserine from the inner to the outer membrane leaflet of cells and exosomes. Altogether, and even individually, these features provide strong immune-suppressive signals. The downstream effects of an enhanced HIF-1α expression include (a) an activation of immune-suppressive effects (recruitment and stimulation of immune-suppressor cells [e.g., Treg, MDSC], secretion of immune-suppressive TH2-type cytokines), and (b) inhibition of antitumor immune responses (inhibition of immune cell actions [e.g., NK, NKT, CD4 + , CD8 + ], inhibition of antigen-presenting cells [e.g., DC], reduced production of immune-stimulatory TH1-type cytokines).

Thermography-controlled, water-filtered infrared-A (wIRA) is a novel, effective and approved heating technique listed in the ESHO quality assurance guidelines for superficial hyperthermia clinical trials (2017). In order to assess the special features and the potential of wIRA-hyperthermia (wIRA-HT), detailed and updated information about its physical and photobiological background is presented. wIRA allows for (a) application of high irradiances without skin pain and acute grade 2-4 skin toxicities, (b) prolonged, therapeutically relevant exposure times using high irradiances (150-200 mW/cm 2 ) and (c) faster and deeper heat extension within tissues. The deeper radiative penetration depth is mainly caused by forward Mie-scattering. At skin surface temperatures of 42-43 °C, the effective heating depth is 15 mm (T ≥ 40 °C) and 20 mm (T ≥ 39.5 °C). Advantages of wIRA include its contact-free energy input, easy power steering by a feed-back loop, extendable treatment fields, real-time and noninvasive surface temperature monitoring with observation of dynamic changes during HT, and - if necessary - rapid protection of temperature-sensitive structures. wIRA makes the compliant heating of ulcerated and/or bleeding tumors possible, allows for HT of irregularly shaped and diffusely spreading tumors, is independent of individual body contours, allows for very short 'transits' between HT and RT (1-4 min) or continuous heating between both therapeutic interventions. New treatment options for wIRA-HT may include malignant melanoma, vulvar carcinoma, skin metastases of different primary tumors, cutaneous T-and B-cell lymphoma, large-area hemangiomatosis, inoperable squamous cell, basal cell and eccrine carcinoma of the skin with depth extensions ≤20 mm.

Tumor hypoxia is a major factor inducing resistance to radiotherapy. Spatial limitation in oxygen (O 2 ) diffusion usually leads to chronic hypoxia, whereas temporary shut-down of perfusion or fluctuations in red blood cell flux can cause acute hypoxia. Since the role of temporal heterogeneity of pO 2 in acute hypoxia during radiotherapy remains unclear, this study focuses on analyzing the influence of temporal heterogeneity of tumor hypoxia upon radiotherapy by modeling the temporal variance of acute hypoxia. The computational simulation was conducted on digital 2D tumor phantoms. The O 2 diffusion and consumption within the tumor tissues were calculated using the reaction-diffusion equation. A total of nine experimental tumor lines (FaDu, GL, C3H, RIF, SCCVII, KHT, MEF, MTG, HT29) were modeled according to known pO 2 distributions. Each tumor line was first simulated 36 times with various temporal heterogeneities (dynamic hypoxia) and once again without temporal heterogeneity (static hypoxia). Temporal pO 2 fluctuations were modeled according to known red blood cell (RBC) fluxes. All tumor phantoms were irradiated with 30 fractions of 2 Gy. Cell survival was calculated as a function of pO 2 and radiation dose via linear quadratic model. The simulation results indicate that the temporal heterogeneity varies with different tumor types, and tumor line HT29 shows the most significant impact of temporal heterogeneity upon the treatment effect. The ratio between the surviving fractions without and with temporal variance ranges from 1.44 to 6.28. Given the same mean pO 2 , the fraction of killed tumor cells in dynamic hypoxia is higher than in static hypoxia. A temporal heterogeneity index (THI) denoting normalized average pO 2 temporal variance is proposed. The results show that for similar mean tumor pO 2 , a strong inverse correlation between THI and the surviving fraction is observed for each tumor line. THI is highly proportional to the fraction of acute hypoxia and to the RBC flux. The proposed THI corresponds well to the fraction of acute hypoxia.

In this minireview, we aim to highlight key factors of the tumor microenvironment, including adenosine, lactate, acidosis, vascular endothelial growth factor, phosphatidylserine, high extracellular K + levels, and tumor hypoxia with respect to antitumor immune functions. Most solid tumors have an immature chaotic microvasculature that results in tumor hypoxia. Hypoxia is a key determinant of tumor aggressiveness and therapy resistance and hypoxia-related gene products can thwart antitumor immune responses.

Patients with cancer are at particularly high risk for malnutrition because both the disease and its treatments threaten their nutritional status. Yet cancer-related nutritional risk is sometimes overlooked or under-treated by clinicians, patients, and their families. The European Society for Clinical Nutrition and Metabolism (ESPEN) recently published evidence-based guidelines for nutritional care in patients with cancer. In further support of these guidelines, an ESPEN oncology expert group met for a Cancer and Nutrition Workshop in Berlin on October 24 and 25, 2016. The group examined the causes and consequences of cancer-related malnutrition, reviewed treatment approaches currently available, and built the rationale and impetus for clinicians involved with care of patients with cancer to take actions that facilitate nutrition support in practice. The content of this position paper is based on presentations and discussions at the Berlin meeting. The expert group emphasized 3 key steps to update nutritional care for people with cancer: (1) screen all patients with cancer for nutritional risk early in the course of their care, regardless of body mass index and weight history; (2) expand nutrition-related assessment practices to include measures of anorexia, body composition, inflammatory biomarkers, resting energy expenditure, and physical function; (3) use multimodal nutritional interventions with individualized plans, including care focused on increasing nutritional intake, lessening inflammation and hypermetabolic stress, and increasing physical activity., (Copyright © 2017 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.)

Background: PET-CT is widely used for both the staging and planning of primary or neoadjuvant chemoradiotherapy for esophageal cancer. Inclusion of PET-CT information into radiotherapy planning often leads to substantial modifications of the target volume. In the case of detection of distant metastases, it may also result in a switch to a palliative treatment approach. This spares patients from therapy-related toxicities that provide no clinical benefit. However, due to a lack of studies, it is currently unclear whether the advantages of PET-CT also translate into a measurable improvement in patient survival., Patients and Methods: A retrospective analysis assessed the survival data of 145 patients with esophageal carcinoma stages I (eight patients; 5%), II (45; 31%), III (79; 55%), IV (8; 5%) and unknown (5; 4%). Patients were treated between 1999 and 2014 either with primary chemoradiation (n = 101) or neoadjuvant chemoradiation at the Department of Radiation Oncology, University Medical Center Mainz, followed by transabdominal or transthoracic tumor resection (n = 44). Of the 145 patients, 64 (44%) had undergone PET-CT., Results: Univariate analysis showed the use of PET-CT to be associated with significantly longer local recurrence-free survival (p = 0.006) and tended to translate into a measurable improvement of overall survival (p = 0.071). Since more patients underwent surgery in the group planned using PET-CT (20% vs. 44%; p = 0.002), we carried out a multivariate Cox regression analysis to adjust for this possible confounding factor. Surgery (p = 0.042; HR 0.55; 95% confidence interval: 0.31-0.98) as well as the use of PET-CT (p = 0.048; HR 0.60; 95% confidence interval: 0.36-0.99) nearly halved the risk of local recurrence. It was only in the group of patients with PET-CT that a trend towards a shorter overall survival was evident in lymph node-positive patients (p = 0.16), whereas nodal stage did not impact on survival in patients staged without PET-CT (p = 0.97)., Conclusion: To the best of our knowledge these data suggest for the first time that the use of PET-CT in the framework of staging and planning of primary or neoadjuvant chemoradiotherapy for esophageal cancer has a favorable impact on patient survival.

Radiation biology is a highly interdisciplinary field at the interface of biology, physics, and medicine. It is characterized by rapid advances in biological and technical knowledge. The potential for using these advances to optimize medical care, radiation protection, and related fields can be exploited only with complementary activities to support the education of young academics. A small number of academic institutions have committed resources into radiation-related courses and curricula; however, few offer a comprehensive interdepartmental research and training program. At the Technical University of Munich (TUM), a full Master of Science (MSc) course in radiation biology has been established. This article describes the TUM MSc radiation biology program, discusses the scope of the field, the teaching goals, and the interdisciplinary curriculum. Detailed information on the full MSc program can be found continuously updated at www.radonc.med.tum.de/masterradiationbiology.