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Background: Two Bispectral contrast enhancement approaches for the fluorescence diagnosis with chlorine-e6 and a wide field-of-view imaging system with fluorescence excitation at 405 nm and time-resolved background suppression were analyzed and compared., Methods: Two techniques for the contrast enhancement of a fluorescent video system (Red/Green (R/G) ratio and Red-Green (R-G)) with time-resolved background suppression for fluorescent diagnosis (FD) were tested in four patients with basal cell carcinoma (BCC)., Results: The results of both contrast enhancement methods were compared for the diagnostic efficiency for FD of BCC. Both techniques successfully determined the boundaries of the lesions and the fluorescence intensity., Conclusions: Both contrast enhancement modes have proven effective in identifying tumor borders in cases of low contrast in BCC FD with Ce6. While the Red/Green (R/G) mode provides sharper lesion borders, the Red minus Green (R-G) mode visualizes more fluorescent features and makes it easier to assess the lesion margins., (Copyright © 2023 The Author(s). Published by Elsevier B.V. All rights reserved.)

The therapeutic properties of 5-aminolevulinic acid (5-ALA) have been extensively studied for cancer detection and treatment using photodynamic therapy (PDT). When administered externally, 5-ALA is converted to protoporphyrin IX (PpIX) in cancer cells, which generates reactive oxygen species (ROS) upon exposure to light. This process enables targeted cell death induction and cancer detection. Given the highly conserved nature of heme biosynthesis over billions of years, we hypothesized that natural mechanisms might exist to prevent excessive accumulation of PpIX or heme resulting from 5-ALA overload. Therefore, we anticipated alterations in protein expression profiles upon exogenous administration of 5-ALA. To understand cellular responses to 5-ALA, we investigated protein expression changes and identified OR1B1 as a promising target in bladder, prostate, lung, and cervical cancer cells. OR1B1 expression was observed only with 5-ALA and ferrous chloride, highlighting the central role of heme in this discovery. Immunofluorescence and electron microscopy confirmed OR1B1's sub-cellular localization. These findings suggest that 5-ALA transformation in cancer cells and OR1B1 expression have potential for enhancing cancer detection and developing alternative treatments, including immunotherapy. This approach overcomes the limitations of PDT and opens new avenues for effective and targeted cancer interventions., Competing Interests: Declaration of Competing Interest 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., (Copyright © 2023 The Authors. Published by Elsevier B.V. All rights reserved.)

Background: Fluorescence diagnostics with two different wide field-of-view imaging systems with fluorescence excitation at 405 nm and 635 nm, respectively, were compared. Both systems include fluorescence quantification and experimental geometry normalization algorithms., Methods: A newly developed system with an excitation wavelength of 405 nm was tested on intralipid fluorescent tumor phantoms with chlorin-e6. Both, this new system and a second existing system with an excitation wavelength of 635 nm, were used for fluorescent diagnosis in six patients with basal cell carcinoma and cancer of the oral mucosa. For PDT, a red diode laser with a wavelength of 660 nm was used for all 6 patients. One patient received an additional irradiation using the red LED source of the new system RESULTS: The boundaries of the lesions and the fluorescence intensity were successfully determined by both video systems., Conclusions: Both fluorescence imaging approaches showed comparable contrast between diseased and healthy tissues. For oral mucosal cancer, a system with violet fluorescence excitation, bispectral frame analysis, and time-resolved background suppression showed better contrast between the tumor and normal tissue and effective elimination of autofluorescence. Moreover, both systems provided efficient quantification of fluorescence and gave fluorescence indices that were weakly dependent on the distance between the device and the tissue., Competing Interests: Declaration of Competing Interest The authors declare that they have no conflict of interest., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Diseases are often accompanied by abnormal expression of gaseous signaling molecules including nitric oxide (NO), carbon monoxide (CO), and hydrogen sulfide (H 2 S). Sensing these gaseous markers is thus important for identification and investigation of pathological processes. In contrast to conventional approaches, such as electrochemical, chromatographical methods, etc., optical imaging shows merits including high sensitivity, good spatiotemporal resolution, and ideal selectivity. Especially, optical molecular probes with aggregation-induced emission (AIE) properties have good potential for bio-detection since they show maintained optical signals in the aggregated state. Recently, many AIE molecular probes have been developed for imaging disease-related gaseous signaling molecules. Generally, these probes recognize the analytes through turn-on or ratiometric approaches. This review summarizes the recent progress in organic probes with AIE properties for sensing gaseous markers and relative disease diagnosis applications. Based on the types of analytes, the probes are divided into three groups: NO, CO and H 2 S sensors. Molecular designs and sensing mechanisms of these AIE probes are highlighted. Their gaseous signaling molecules detection applications at cellular and animal levels are presented. Finally, some existing problems and future promising development directions are discussed with the hope to inspire further developments of AIE probes for precise disease diagnosis., Competing Interests: Declaration of competing interest 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., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Bladder cancer is a common disease with a high recurrence rate. In order to improve the treatment of superficial bladder tumors, we evaluated the efficacy and safety of transurethral resection (TURB) followed by fluorescence diagnosis (FD) and photodynamic therapy (PDT) with chlorin e 6 photosensitizers (PSs), viz . "Fotoran e 6 " and "Fotoditazin". It was found that both PSs generated singlet oxygen and revealed moderate affinity toward the lipid-like compartment. Between November 2018 and October 2020, 12 patients with verified non-muscle invasive bladder cancer (NMIBC) were treated by TURB combined with FD and PDT. Eight patients received "Fotoran e 6 " intravenously, while four patients received intravesical PSs. The patient ages were between 31 and 79 years, with a median age of 64.5 years (mean 61.3 ± 14.2). The total light dose was 150 J/cm 2 for the local irradiation of the tumor bed with a red light at the λ = 660 nm wavelength, and 10-25 J/cm 2 were additionally delivered for diffuse irradiation of the entire bladder mucosa. At the median follow-up period of 24 months (mean 24.5 ± 5.4 months, range 16-35 months), 11 patients remained tumor-free. One 79-year-old patient developed a recurrence without progression to the muscle layer. This pilot study shows that the TURB + FD + PDT technique is an effective and safe option for the first-line treatment of superficial bladder tumors.

Photodynamic therapy (PDT) is a promising approach for the targeted treatment of cancer and various other human disorders. An effective, clinically approved approach in PDT involves the administration of 5-aminolevulinic acid (ALA) to generate elevated levels of the natural photosensitiser protoporphyrin IX (PpIX). The development of prodrugs of ALA is of considerable interest as a means to enhance the efficiency and cell selectivity of PpIX accumulation for PDT applications. In this work a novel peptide-targeted dendrimeric prodrug of 5-aminolevulinic acid (ALA) 13 was synthesised which displays nine copies of ALA on a core structure that is linked to a homing peptide for targeted delivery to a specific cancer cell type. The synthesis was accomplished effectively via a flexible, modular solid phase and solution phase route, using a combination of solid phase peptide synthesis and copper-catalysed azide-alkyne cycloaddition chemistry. The prodrug system shows a sustained and enhanced production of protoporphyrin IX (PpIX) in the MDA-MB-231 cell line that over-expresses the epidernal growth factor receptor (EGFR+) in comparison to equimolar ALA and the corresponding non-targeted ALA dendrimer (nine copies of ALA). This study provides a proof of concept for the development of a new generation of prodrugs for ALA-based photodynamic therapy that can deliver an enhanced ALA payload to specific tissue types., (Copyright © 2021 Elsevier Inc. All rights reserved.)

The aim of the study was to assess the capabilities of combined application of dual-wavelength fluorescence visualization and contactless skin thermometry during photodynamic therapy monitoring (PDT) of basal cell cancer., Materials and Methods: The study was performed at the University Clinic of Privolzhsky Research Medical University (Nizhny Novgorod). Nine clinically, dermatoscopically, and histologically verified foci of basal cell skin cancer were exposed to PDT sessions (wavelength of 662 nm, light dose density of 150 J/cm 2 ) with systemic application of chlorin-based photosensitizer Fotoditazin. A semiconductor laser system Latus-T (Russia) was employed for irradiation. Dual-wavelength fluorescence visualization and contactless thermometry with an IR pyrometer were used to monitor the PDT sessions., Results: The PDT sessions of nine foci of basal cell cancer were carried out under the control of fluorescence imaging and contactless thermometry. Photosensitizer photobleaching in all foci amounted to 40% signifying a percent of photosensitizer involved in the photodynamic reaction. It has been shown that the combined employment of dual-wavelength fluorescence monitoring and contactless thermometry during the PDT of basal cell skin cancer allows oncologists to control simultaneously the degree of photosensitizer photobleaching and the depth of the photodynamic effect in tissues, the extent of involving the mechanisms associated with hyperthermia as well as the correctness of the procedure conducting. In the course of 9-month dynamic follow-up after the treatment, no clinical and dermatoscopic signs of recurrence were found., Conclusion: A bimodal control of PDT enables the assessment of the correctness and efficacy of the procedure performance. The contactless control of tissue heating allows ensuring the temperature mode for hyperthermia realization, while the fluorescence monitoring makes it possible to evaluate the accumulation of the photosensitizer in the tumor and the depth of the PDT action as well as to predict the procedure efficacy based on the photobleaching data. The complementary use of these techniques allows the adjustment of the mode directly in the course of the PDT procedure. The acquisition of the sufficient statistical data on the combined monitoring will result in the development of a novel PDT protocol., Competing Interests: Conflicts of interest. The authors have no conflicts of interest to declare.

In recent years, fluorescence navigation has been increasingly used in surgery for gliomas. In most studies, 5-ALA derivatives are used as fluorescence inducers. However, there are few data regarding E6 chlorin for these purposes., Objective: To evaluate an effectiveness and feasibility of fluorescence navigation with chlorin E6 in surgery of brain gliomas., Material and Methods: The study included 30 patients with glial brain tumors grade II-IV. All patients were operated at the Polenov Russian Neurosurgical Institute. We used surgical microscope (Leica OHS-1), D-Light AF System (Karl Storz, Germany), original fluorescence module (St. Petersburg LOMO, developed by G.V. Papayan) and special software RSS Cam - Endo 1.4.313 for visual analysis of fluorescence. Histological examination included hematoxylin-eosin staining of specimens and immunohistochemical studies., Results: Fluorescence was weak in all patients with Grade II gliomas and strong in almost all patients with Grade III-IV gliomas. Sensitivity of fluorescence diagnosis with chlorin E6 was 72.2% for Grade II gliomas, 83.8% for Grade III gliomas and 87.7% for Grade IV. Specificity of this method was 60% for Grade II gliomas, 66.7% for Grade III gliomas and 85.2% for Grade IV., Conclusion: Certain method of fluorescence imaging ensured resection of glial brain tumors using chlorin E6. Intensity of tumor fluorescence correlated with glioma malignancy grade. These results indicate that chlorin E6 is an effective photosensitizer for intraoperative fluorescence diagnosis in surgery for glioma.

Photodynamic therapy (PDT) is an effective treatment option for the treatment of superficial basal cell carcinoma (sBCC). Recent publications have demonstrated that PDT with 7.8% 5-aminolaevulinic acid nanoemulsion-based gel (BF-200 ALA-PDT) is an effective and safe alternative for the treatment of sBCC). To investigate the efficacy and safety of 7.8% 5-aminolaevulinic acid nanoemulsion-based gel (BF-200 ALA)-PDT for the treatment of sBCC. A non-controlled, open-label single centre study was conducted. Patients received one PDT cycle with two PDT sessions one-week apart. In case that clinical-dermoscopy evaluation of treatment outcome revealed remaining lesions, a second PDT cycle was performed. The clinical results at the dermoscopy and fluorescence diagnosis level were histologically confirmed in all patients. Treatment response was evaluated 3, 6, and 12 months after last PDT session. A total of 31 patients (12 men and 19 women), with a median age of 63.74 years were included in this study. 3-month after PDT-session, 23/31 patients were complete responders (74.19%) after two BF-200 ALA -PDT sessions. Esthetic outcome was considered good-to-excellent. 5 Aminolevulinic acid 7.8% nanoemulsion-based gel (BF-200 ALA) PDT is an effective therapy option for the treatment of sBCC. Complete clearance rates were higher in those patients who received only one PDT cycle. These results show a similar tendency as shown in other publications., (© 2020 Wiley Periodicals LLC.)

Tumor borders are one of the most significant characteristics of any tumor, including that of the skin., Purpose: To compare histological borders of periorbital skin tumors with their autofluorescence borders built from the analysis of non-induced protoporphyrin IX autofluorescence., Material and Methods: The study group included 8 patients with skin tumors of the eyelids, periorbital region, eyebrow and zygomatic regions aged 54-88 years. The tumors varied in size from 2 to 8 mm and all displayed signs of basal cell carcinoma (BCC). At admission, all the patients underwent non-induced autofluorescence diagnosis. The images were processed with the «CancerPlot» program. During radio excision, the autofluorescent border of each neoplasm was marked with a surgical incision of about 5 mm long and 2 mm deep., Results: Upon pathomorphological examination, solid BCC was identified in 7 cases. The remaining case was senile keratosis. All reference incisions were located in healthy tissues not farther than 1 mm from the tumor (or keratosis locus, correspondingly)., Conclusion: By the example of facial BCC, an evident correlation was established between histological borders of the tumor and its native (non-induced) protoporphyrin IX autofluorescence.

Objective: This study is to analyze fluorescence sensitivity in the diagnosis of brain and spinal cord tumors. Material and methods: The authors conducted a multicenter retrospective analysis of data on 653 cases in 641 patients: 553 of them had brain tumors and 88 spinal cord tumors. Brain tumor resection was performed in 523 patients, of whom 484 were adults and 39 children. The analyzed series was presented by 320 gliomas, 101 meningiomas, and 72 metastases. A stereotactic biopsy was performed in 20 patients and endoscopic surgery in 10 patients. In all cases, 20 mg/kg of 5-Aminolaevulinic acid was administered orally 2-h before surgery. All surgical interventions were performed with a microscope BLUE 400 to visualize fluorescence, while endoscopic surgery-with an endoscope equipped with a fluorescent module. Fluorescence spectroscopy was conducted in 20 cases of stereotactic biopsies and in 88 cases of spinal cord tumors. Results: Among adult brain tumors operated by microsurgical techniques, meningiomas showed the highest 5-ALA fluorescence sensitivity 94% ( n = 95/101), brain metastases 84.7% ( n = 61/72), low-grade gliomas 46.4% ( n = 26/56), and high-grade gliomas 90.2% ( n = 238/264). In children the highest 5-ALA visible fluorescence was observed in anaplastic astrocytomas 100% ( n = 4/4) and in anaplastic ependymomas 100% ( n = 4/4); in low-grade gliomas it made up 31.8% ( n = 7/22). As for the spinal cord tumors in adults, the highest sensitivity was demonstrated by glioblastomas 100% ( n = 4/4) and by meningiomas 100% ( n = 4/4); Fluorescence was not found in gemangioblastomas ( n = 0/6) and neurinomas ( n = 0/4). Fluorescence intensity reached 60% ( n = 6/10) in endoscopic surgery and 90% ( n = 18/20) in stereotactic biopsy. Conclusion: 5-ALA fluorescence diagnosis proved to be most sensitive in surgery of HGG and meningioma (90.2 and 94.1%, respectively). Sensitivity in surgery of intracranial metastases and spinal cord tumors was slightly lower (84.7 and 63.6%, correspondingly). The lowest fluorescence sensitivity was marked in pediatric tumors and LGG (50 and 46.4%, correspondingly). Fluorescence diagnosis can also be used in transnasal endoscopic surgery of skull base tumors and in stereotactic biopsy.

Background: The establishment of a precise and rapid method to detect metastatic lymph nodes (LNs) is essential to perform less invasive surgery with reduced gastrectomy along with reduced lymph node dissection. We herein describe a novel imaging strategy to detect 5-aminolevulinic acid (5-ALA)-induced protoporphyrin IX (PpIX) fluorescence in excised LNs specifically with reduced effects of tissue autofluorescence based on photo-oxidation of PpIX. We applied the method in a clinical setting, and evaluated its feasibility., Methods: To reduce the unfavorable effect of autofluorescence, we focused on photo-oxidation of PpIX: Following light irradiation, PpIX changes into another substance, photo-protoporphyrin, via an oxidative process, which has a different spectral peak, at 675 nm, whereas PpIX has its spectral peak at 635 nm. Based on the unique spectral alteration, fluorescence spectral imaging before and after light irradiation and subsequent originally-developed image processing was performed. Following in vitro study, we applied this method to a total of 662 excised LNs obtained from 30 gastric cancer patients administered 5-ALA preoperatively., Results: Specific visualization of PpIX was achieved in in vitro study. The method allowed highly sensitive detection of metastatic LNs, with sensitivity of 91.9% and specificity of 90.8% in the in vivo clinical trial. Receiver operating characteristic analysis indicated high diagnostic accuracy, with the area under the curve of 0.926., Conclusions: We established a highly sensitive and specific 5-ALA-induced fluorescence imaging method applicable in clinical settings. The novel method has a potential to become a useful tool for intraoperative rapid diagnosis of LN metastasis., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Background: The preferential accumulation of 5-aminolaevulinic acid (ALA)-induced protoporphyrin IX (PpIX) in neoplastic cells supports its potential use in the photodetection of epithelial tumours through porphyrin fluorescence., Objective: To assess the validity of fluorescence diagnosis (FD) as an efficient pre-surgical in vivo imaging tool for defining the lateral boundaries of various types of basal cell carcinomas (BCCs)., Methods: The BCC tumour area was determined for 27 patients using FD digitalized imaging system, where the accumulation of PpIX in tumour tissue in relation to normal tissue was measured. Subsequently, BCCs were excised according to the complete area defined by FD using Mohs micrographic surgery (MMS)., Results: Of the 27 BCCs, the FD margin of the lesion coincided with the histopathological picture in 12 BCCs (44.44%). The mean value of accumulation factor (AF) was 2.7. Although 17 pigmented BCCs showed attenuated or absent fluorescence in the center, fluorescence at their periphery was used as a guide for excision, and statistically, the pigmentation of the BCCs showed no effect on the results of the FD efficacy (p=1.0)., Conclusion: Fluorescence diagnosis of BCC may be beneficial as a guide to the safety margin needed before MMS. The safety margin is decided according to the FD tumour diameter in relation to the clinical tumour diameter., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Purpose: Overexpression of epidermal growth factor receptor (EGFR) is observed in oral squamous cell carcinoma (OSCC) and is associated with increased proliferation, metastasis and therapeutic resistance. We aim to develop a novel drug delivery system comprised of a photosensitizer Chlorin e6 (Ce6) that is encapsulated in a viral envelope and tagged with anti-EGFR antibody to target OSCC., Methods: Ce6 was encapsulated in both virosomes (Ce6-Vir) and virosomes tagged with anti-EGFR antibody (Ce6-Vir-EGFR'). In vitro studies were conducted to assess the cellular uptake and bioavailability of the photosensitizer in OSCC cells. Ce6 alone or in constructs was then administered in a hamster cheek pouch model and fluorescence imaging and spectroscopy was performed., Results: In vitro results showed that the uptake of Ce6-Vir-EGFR' was lower than that for Ce6-Vir and Ce6 possibly due to its large size. Nevertheless, in vivo results showed significant tumor specificity of Ce6-Vir-EGFR' compared to Ce6. The tumor to normal mucosa ratio showed that Ce6-Vir-EGFR' can successfully target OSCC lesions and therefore shows potential for use in fluorescence diagnosis of OSCC., Conclusions: Both the virosome-Ce6 constructs were internalized by OSCC cells and successfully used for fluorescence imaging. Tagging with anti-EGFR antibody further improved the targeting ability toward OSCC., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Background: Basal cell carcinoma (BCC) is the most frequent malignant tumor of the skin. The high prevalence of BCC, the risk of local recurrence, and the difficult clinical identification of the excision margins emphasize the importance of studying new approaches, ensuring complete surgical excision that allows preservation of normal tissue, especially for BCCs located on cosmetically important areas such as the mid face. Photodiagnosis (PD) is a pre-operative technique that allows a more accurate distinction of neoplastic lesions from surrounding healthy skin in vivo., Purpose: The aim of this study is to assess the usefulness of PD for the evaluation of tumor margins in 10 patients with recurrent BCC of the face., Methods: We study the red fluorescence emitted by neoplastic tissue under a Wood's lamp irradiation, after accumulation of methyl amino levulinate (MAL) cream in 10 patients with recurrent BCC., Results: Our histologic analysis of perilesional skin by PD allowed to delineate more precise tumor margins, thus achieving radical excision in 90% of patients., Conclusion: PD represents a diagnostic method that helps to distinguish between tumor tissue and surrounding healthy tissue especially in case of recurrent BCC of the face when the clinical delimitation is not clear., (© 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Background: Monitoring of tumor burden during mycosis fungoides (MF) treatment, is crucial to adjust therapy accordingly. This is usually achieved through combined by clinical assessment with histopathological and immunohistochemical evaluation., Aim: To assess the validity of fluorescence diagnosis (FD) in the measurement of response to therapy in early MF, using in comparison flow cytometric technique of skin biopsies for CD4+/CD7- malignant T-cell count before and after therapy., Patients and Methods: Twenty-two patients of histologically proven early MF (stages Ia, Ib, IIa) were subjected to fluorescence diagnosis of their most affected skin lesion before and after 12 weeks of phototherapy with or without combination therapy. In comparison flow cytometric assessment of skin biopsies for CD4+/CD7- malignant T-cell count was evaluated before and after therapy from skin biopsy of the same lesion., Results: All tested MF lesions showed varying degrees of fluorescence by FD at week zero, with a mean accumulation factor (AF), which is the fluorescence ratio between the tumor tissue and normal skin, of 2.2. After 12 weeks of therapy, the mean AF showed significant reduction to 1.94 (p=0.009). The percent of CD4+/CD7- cells dropped significantly after treatment (p=0.029). No correlation between CD4+/CD7- cell counts and the mean AF could be deduced., Conclusion: In cases of mycosis fungoides, fluorescence diagnosis can represent an effective tool for evaluating the response to therapy. Changes in accumulation factor values can be used for follow-up of therapy in the same patient, but it should not be used as an absolute value., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Background: As carcinogenesis is often accompanied by inflammation, fluorescence diagnosis (FD) of tumours reportedly leads to false positive results. However, an influence of inflammation on the efficiency of photodynamic therapy (PDT) is not known., Objective: Therefore we investigated whether LPS-induced expression of the pro-inflammatory cytokine interleukin-6 (IL-6) influences hypericin and protoporphyrin IX (PpIX) accumulation, and their photocytotoxicity. As in vitro models served normal and malignant human skin cell lines. Additionally we analyzed whether low-dose photodynamic treatment as found during FD and sublethal PDT could modulate the expression of IL-6 and other cytokines as low-dose PDT has the potential for treatment of inflammatory skin diseases., Methods: Cells were pre-incubated with LPS to induce a pro-inflammatory milieu. Photosensitizer accumulation and toxicity were measured by a microplate reader, IL-6 via Sandwich ELISA and the other cytokines via a Multiplex Immunoassay., Results and Conclusions: Neither hypericin uptake nor PpIX accumulation was influenced by the proinflammatory state. The false positive classification in FD of patients could rather be due to sensitizer-loaded immune cells. On the other hand, low dose PDT is able to significantly reduce the level of IL-6 in all cell lines. Under differing PDT-conditions, PDT can enhance IL-6 in malignant cells, which could elicit a specific anti-tumour immune response. Furthermore, hypericin alone is able to up-regulate the anti-inflammatory cytokines IL-4, -5 and -10, which could be useful to reduce excessive inflammation. LPS-induction has no additional influence in most cases. Some of these findings could contribute to abate inflammatory diseases on skin or promote wound healing., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Fluorescence diagnostic methods enable tumor visualization via specific excitation of endogenous or exogenous tumor-selective fluorescent markers and subsequent optical measurement of the induced fluorescence signals. In the following review, the reader will be given a clear and extensive understanding of all aspects of these methods relevant for ENT specialists. Apart from a demonstration of the clinical difficulties in the diagnosis of malignant tumors of the upper aerodigestive tract, a historical synopsis of fluorescence diagnosis and an explanation of the biophysical basics, this publication focuses mainly on a detailed discussion of the current status of research and a critical consideration of the commercially available systems for fluorescence diagnosis in ENT oncology. The topic is rounded off by a short account of possible future activities in this field.