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Introduction: Pelvic internal organs change in volume and position during radiotherapy. This may compromise the efficacy of treatment or worsen its toxicity. There may be limitations to fully correcting these changes using online image guidance; therefore, effective and consistent patient preparation and positioning remain important. This review aims to provide an overview of the extent of pelvic organ motion and strategies to manage this motion. Methods and Materials: Given the breadth of this topic, a systematic review was not undertaken. Instead, existing systematic reviews and individual high-quality studies addressing strategies to manage pelvic organ motion have been discussed. Suggested levels of evidence and grades of recommendation for each strategy have been applied. Results: Various strategies to manage rectal changes have been investigated including diet and laxatives, enemas and rectal emptying tubes and rectal displacement with endorectal balloons (ERBs) and rectal spacers. Bladder-filling protocols and bladder ultrasound have been used to try to standardise bladder volume. Positioning the patient supine, using a full bladder and positioning prone with or without a belly board, has been examined in an attempt to reduce the volume of irradiated small bowel. Some randomised trials have been performed, with evidence to support the use of ERBs, rectal spacers, bladder-filling protocols and the supine over prone position in prostate radiotherapy. However, there was a lack of consistent high-quality evidence that would be applicable to different disease sites within the pelvis. Many studies included small numbers of patients were non-randomised, used less conformal radiotherapy techniques or did not report clinical outcomes such as toxicity. Conclusions: There is uncertainty as to the clinical benefit of many of the commonly adopted interventions to minimise pelvic organ motion. Given this and the limitations in online image guidance compensation, further investigation of adaptive radiotherapy strategies is required. [ABSTRACT FROM AUTHOR]

• Oxygen fixes DNA damage by free radicals and cells are 2–3 times more radioresistant to sparsely ionising radiation when irradiated in the absence of oxygen. • OER, the ratio of radiation dose in hypoxia divided by radiation dose in air to produce the same biological effect, decreases with increasing LET. • Reoxygenation occurs during a course of fractionated radiotherapy making tumours cells more sensitive to radiation. • All solid tumour have some level of hypoxia that promotes angiogenesis and metastasis – it is associated with an aggressive phenotype. • High levels of tumour hypoxia are associated with a poor prognosis, hypoxia modification strategies are effective and patients with the most hypoxic tumours benefit most from hypoxia modifying treatments. [ABSTRACT FROM AUTHOR]

The article focuses on the use of Fluorine-18 fluorodeoxyglucose (FDG) positron emission tomography-computerized tomography (PET-CT) as tool for assessment following chemoradiotherapy for head and neck squamous cell carcinoma. Topics discussed include inclusion of squamous cell carcinoma of oropharynx and larynx among patients, absence of anatomical abnormality on the Computed Tomography (CT), and demonstration of metabolic response with regard to lymph node disease.

Objective: To assess the accuracy of a 4-month post- (chemo)radiotherapy 18-fiudeoxyglucose (18F-FDG) positron emission tomography (PET)-CT for head and neck squamous cell carcinoma (HNSCC), Methods: 105 patients who underwent a baseline and response assessment 18F-FDG PET-CT scan between 2008 and April 2013 were identified. 18F-FDG PET-CT outcomes were analysed with reference to clinicopathological outcomes. Results: 79 of 105 (75%) 18F-FDG PET-CT scans demonstrated a complete metabolic response: 19 of 101 (19%) for assessable primary tumours were positive; and 19 of 93 (20%) for patients with nodal disease were equivocal (n = 10) or positive (n = 9). The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) for primary and nodal disease were 90%, 89%, 47%, 99% and 91%, 89%, 53% and 99%, respectively. Eight of nine patients with a positive nodal response scan had clinicopathological evidence of residual nodal disease (PPV, 89%). 2 of 10 patients with equivocal nodal responses had clinicopathological evidence of residual nodal disease (PPV, 20%). Conclusion: 18F-FDG PET-CT 4 months post treatment has a very high NPV. A positive 18F-FDG PET-CT has a high PPV for residual nodal disease. By contrast, patients who have an equivocal nodal response have a low PPV. Advances in knowledge: Response assessment 18F-FDG PET-CT is a valuable tool in guiding the selective use of neck dissection following (chemo)radiotherapy for HNSCC. An equivocal lymph node response has a limited predictive value for persistent disease, and optimal management remains a clinical challenge. [ABSTRACT FROM AUTHOR]

Poster: Clinical track: Prostate PO-1180: Patterns of failure after stereotactic ablative radiotherapy for abdomino-pelvic nodal disease F. Slevin, A. Littlejohns, P. Dickinson, K. Franks, R. Goody, R. Speight, J. Lilley, L. Murray, A. Henry. [Extracted from the article]

Poster: Clinical track: Gynaecological (endometrium, cervix, vagina, vulva) PO-1147: Salvage radiotherapy for recurrent endometrial cancer: predictors of outcome. H. Almasri, R. Cooper, F. Slevin, K. Cardale. [Extracted from the article]

Poster: Physics track: Intra-fraction motion management PO-1638: Treatment delivery uncertainties in rectal cancer radiotherapy â evidence-based margin estimates A. Appelt, M. Beasley, M. Teo, F. Slevin, R. Muirhead, D. Sebag-Montefiore, PO-1638: Treatment delivery uncertainties in rectal cancer radiotherapy - evidence-based margin estimates. [Extracted from the article]