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Tumour recurrences after treatment of head and neck squamous cell carcinoma (HNSCC) are more likely to originate from regions of high-baseline FDG-PET uptake. Mid-treatment functional imaging can potentially predict for higher risk of tumour recurrence. The aim of this study is to correlate the location of locoregional tumour recurrence with baseline FDG-PET metabolic volumes and mid-treatment FDG-PET metabolic volumes in patients with HNSCC following definitive radiotherapy.A total of 23 patients with 26 local and/or regional recurrences underwent baseline (W0-PET) and mid-treatment (W3-PET) 18F-FDG PET scans as part of their radiotherapy. FDG-PET-based metabolic volumes (MTV20%, MTV40%, MTV60%, MTV80%, SUV2.5, SUVpeak and PET_EDGE) were delineated onto the FDG-PET scans. The recurrence nidus was identified on FDG-PET at the time of recurrence (REC-PET). DIR-based fusion was performed for REC-PET to W0-PET, and REC-PET to W3-PET. The location of the recurrence nidus was correlated with the FDG-PET volumes. Further analysis included a comparison of the recurrence density to FDG-PET metabolic volumes.Most recurrences occurred within the MTV20%, MTV40% and SUV 2.5 volumes. Sixty-nine per cent of recurrences (18 of 26) occurred within both the W0 MTV40% and W3 MTV40% volumes. A higher recurrence density was seen for iso-SUV contours closer to the maximum SUV for both W0 and W3. For a number of the FDG-PET volumes, including MTV20%, MTV40% and SUV2.5, the recurrence density was improved for W3 compared to W0, however, this improvement was small in magnitude. The average volume of MTV40% contours was considerably smaller than MTV20% and SUV2.5 contours.The metabolic parameters of SUV2.5, MTV20% and MTV40% delineated on the baseline and mid-treatment FDG-PET scans encompassed the majority of recurrences. The MTV40% is significantly smaller, hence, we prefer this volume for future dose escalation studies.

Prostate cancer (PC) is the most common malignancy in men. Internal radiotherapy (brachytherapy) has been used to treat PC successfully for over a century. In particular, there is level-one evidence of the benefits of using brachytherapy to escalate the dose of radiotherapy compared with standard external beam radiotherapy approaches. However, the use of PC brachytherapy is declining, despite strong evidence for its improved cancer outcomes. A method using external beam radiotherapy known as virtual high-dose-rate brachytherapy boost (vHDRB) aims to noninvasively mimic a brachytherapy boost radiation dose plan. In this review, we consider the evidence supporting brachytherapy boosts for PC and the continuing evolution of vHDRB approaches, culminating in the current generation of clinical trials, which will help define the role of this emerging modality.

Background: Smoking status at point of diagnosis is not used in defining risk groups for human papillomavirus (HPV)-associated oropharyngeal cancer (OPC) despite its prognostic value in head and neck cancer. Methods: Retrospective analysis of consecutive patients treated with chemoradiotherapy between January 2005 and July 2017 was performed with multivariable analysis to explore the impact of smoking status at diagnosis (current/former/never) on overall survival (OS), cancer-specific survival (CSS) and progression-free survival (PFS). Results: Median follow-up was 61 months. Four hundred and four patients were included. Current smokers had inferior OS versus never and former smokers [adjusted HR 2.37 (95% CI 1.26–4.45, p < 0.01) and 2.58 (95% CI 1.40–4.73, p < 0.01), respectively] and inferior PFS versus never smokers [adjusted HR 1.83 (95% CI 1.00–3.35, p = 0.04)]. Smoking status did not predict for CSS. Conclusion: Detailed smoking behavior should be considered in refining risk groups in HPV-associated OPC treated with radiotherapy and in future trial design eligibility and stratification.

Radiomics of magnetic resonance images (MRI) in rectal cancer can non-invasively characterise tumour heterogeneity with potential to discover new imaging biomarkers. However, for radiomics to be reliable; the imaging features measured must be stable and reproducible. The aim of this study is to quantify the repeatability and reproducibility of MRI-based radiomic features in rectal cancer. An MRI radiomics phantom was used to measure the longitudinal repeatability of radiomic features and the impact of post-processing changes related to image resolution and noise. Repeatability measurements in rectal cancers were also quantified in a cohort of ten patients with test-retest imaging amongst two observers. We found that many radiomic features; particularly from texture classes, were highly sensitive to changes in image resolution and noise. 49% of features had coefficient of variations ≤ 10% in longitudinal phantom measurements. 75% of radiomic features in in vivo test-retest measurements had an intraclass correlation coefficient of ≥ 0.8. We saw excellent interobserver agreement with mean dice similarity coefficient of 0.95 ± 0.04 for test and retest scans. The results of this study show that even when using a consistent imaging protocol many radiomic features were unstable. Therefore, caution must be taken when selecting features for potential imaging biomarkers.

Purpose To explore site- and clinician-level factors associated with protocol violations requiring real-time-review (RTR) resubmission in a multicenter clinical trial to help tailor future quality assurance (QA) protocols. Methods and Materials RAVES (Radiation Therapy–Adjuvant vs Early Salvage) (Trans-Tasman Radiation Oncology Group 08.03) is a randomized trial comparing adjuvant with early salvage radiation therapy in men with positive surgical margins or pT3 disease after prostatectomy. Quality assurance in RAVES required each clinician and site to submit a credentialing dummy run (DR) and for each patient's radiation therapy plan to undergo external RTR before treatment. Prospectively defined major violations from trial protocol required remedy and resubmission. Site and clinician factors associated with RTR resubmission were examined using hierarchical modeling. Results Data were collected from 171 consecutive patients, treated by 46 clinicians at 32 hospitals. There were 47 RTR resubmissions (27%) due to 65 major violations. The relative rate of resubmission decreased by 29% per year as the study progressed (odds ratio OR. 0.71, P =.02). The majority of resubmissions were due to contouring violations (39 of 65) and dosimetric violations (22 of 65). For each additional patient accrued, significant decreases in RTR resubmission were seen at both clinician level (OR 0.75, P =.02) and site level (OR 0.72, P =.01). The rate of resubmission due to dosimetric violations was only 1.6% after the first 5 patients. Use of IMRT was associated with lower rates of resubmission compared with 3-dimensional conformal radiation therapy (OR 0.38, P =.05). Conclusion Several low- and high-risk factors that may assist with tailoring future clinical trial QA were identified. Because the real-time resubmission rate was largely independent of the credentialing exercise, some form of RTR QA is recommended. The greatest benefit from QA was derived early in trial activation and clinician experience.

Introduction We aimed to quantify a relationship between radiotherapy dose and freedom from biochemical failure (FFBF) in low- and intermediate-risk prostate cancer. To reduce confounding we used data with a standardised end–point, mature follow-up, low competing risk of metastatic failure, conventional fractionation and separate reporting for outcomes with hormonal therapy (HT). Methods A systematic review of the literature was carried out. Studies that reported the use of radiotherapy alone in 1.8–2 Gy fractions in low- and intermediate-risk prostate cancer were included. The primary end–point was Phoenix definition 5-year FFBF. A logistic regression was used to quantify the dose–response relationship. Results Data from eight studies with 3037 patients met the inclusion criteria. The data from 810 low-risk patients and 2245 intermediate-risk patients were analysed. A strong association between radiotherapy dose and FFBF was found in low- and intermediate-risk patients managed with radiotherapy alone. In low-risk patients not treated with HT the dose required to achieve 50% biochemical tumour control (TCD50) is 52.0 Gy and the slope of the dose–response curve at TCD50 (γ50) is 2.1%/Gy. At 78 Gy this represented a FFBF of 90.3%. In intermediate-risk patients not treated with HT the TCD50 is 64.7 Gy and γ50 is 3.2%/Gy. At 78 Gy this translated into a FFBF of 84.3%. HT had a small effect for low-risk patients and an inconsistent effect for intermediate-risk men. Conclusion A strong association was found between radiation dose and biochemical outcome in both low- and intermediate-risk patients. Standardised reporting of results from future studies will make future analyses more robust.

We aimed to quantify a relationship between radiotherapy dose and freedom from biochemical failure (FFBF) in low- and intermediate-risk prostate cancer. To reduce confounding we used data with a standardised end-point, mature follow-up, low competing risk of metastatic failure, conventional fractionation and separate reporting for outcomes with hormonal therapy (HT).A systematic review of the literature was carried out. Studies that reported the use of radiotherapy alone in 1.8-2 Gy fractions in low- and intermediate-risk prostate cancer were included. The primary end-point was Phoenix definition 5-year FFBF. A logistic regression was used to quantify the dose-response relationship.Data from eight studies with 3037 patients met the inclusion criteria. The data from 810 low-risk patients and 2245 intermediate-risk patients were analysed. A strong association between radiotherapy dose and FFBF was found in low- and intermediate-risk patients managed with radiotherapy alone. In low-risk patients not treated with HT the dose required to achieve 50% biochemical tumour control (TCD50 ) is 52.0 Gy and the slope of the dose-response curve at TCD50 (γ50 ) is 2.1%/Gy. At 78 Gy this represented a FFBF of 90.3%. In intermediate-risk patients not treated with HT the TCD50 is 64.7 Gy and γ50 is 3.2%/Gy. At 78 Gy this translated into a FFBF of 84.3%. HT had a small effect for low-risk patients and an inconsistent effect for intermediate-risk men.A strong association was found between radiation dose and biochemical outcome in both low- and intermediate-risk patients. Standardised reporting of results from future studies will make future analyses more robust.