Abstract Book

S128

ESTRO 37

and more in general the meaning of my commitment in ESTRO. SP-0251 Experiences from young scientists: Participant ESTRO Clinical Radiobiology Course J.A. Hundvin 1 1 Haukeland University Hospital, Cancer Treatment and Medical Physics, Bergen, Norway Abstract text One of the first courses to be arranged by ESTRO was focused on radiobiology, which illustrates the central role of said field of study. This contribution will be a presentation on experiences from the Clinical Radiobiology course, organized in Budapest, Hungary, in the spring of 2016. Focus will be set on the academic outcome, as well as the learning methods. Also, the social part of the course will be mentioned briefly. PV-0252 Image-guided boost brachytherapy for anal canal cancer: tumour and functional outcome M. Heilmann 1 , R. Schmid 1 , C. Kirisits 1 , D. Berger 1 , N. Nesvacil 1 , R. Pötter 1 , J. Widder 1 , M. Schmid 1 1 Medizinische Universität Wien, Universtitätklinik für Strahlentherapie, Vienna, Austria Purpose or Objective To analyse clinical outcome in a consecutive cohort of patients with anal cancer treated with external beam radiotherapy (EBRT) +/- chemotherapy and image-guided pulse dose rate brachytherapy (BT). Material and Methods All patients with primary squamous cell cancer of the anal canal referred for primary treatment or after incomplete surgical resection (n=9, 17%) from 2000–2017 receiving PDR-BT as boost in curative intent were included in this retrospective analysis. Treatment consisted of EBRT to the small pelvis to 46 Gy, concomitant chemotherapy with MMC and capecitabine or 5-FU, and an image-guided PDR-BT boost to the primary tumour. Eligibility criteria for BT were: Tumour involving less than half of the anal circumference and < 5cm length at presentation. Reported toxicities were scored according to the CTCAEv4. Descriptive statistics and the Kaplan-Meier method were used for analysis. Results In total, 52 patients were included. Median age was 62.4 years (45 – 90) and 46 (88%) patients were female; 11 (21%) had T1, 31 (60%) T2, 9 (17%) T3, and 1 (2%) T4 primaries. Fifteen patients presented with clinically positive lymph nodes. The mean prescribed EBRT dose was 45.5 Gy (± 3.1 Gy), followed by 14.5 Gy (± 2.0 Gy) PDR-BT boost using single- plain implants. Forty-two (81%) of the patients received concomitant chemotherapy. Median overall treatment time was 53 d (42–115). Image guidance for BT was MRI- based in 15 patients (29%) and CT-based in 37 (71%). With a median follow-up time of 36.6 months, two persistent disease, one local recurrence, and one case with distant metastases were observed. There were two (4%) patients suffering necrosis, two (4%) chronic diarrhea, and seven (13%) fecal incontinence, rendering a 19 % gross G3 toxicity rate (n=11 patients). No G4 or G5 toxicities were observed. Overall survival, local control, and colostomy- free survival at 3 years were 85 %, 93 %, and 91 %, respectively. Conclusion In this monocenter consecutive cohort comprising a selected patient cohort of patients suitable for BT, Poster Viewing : Poster viewing 5: Pelvic brachytherapy

radiochemotherapy combined with image guided PDR-BT seem to compare favourably with published results. A dose-volume-response analysis including patient reported outcomes is ongoing. PV-0253 Importance of DCE- MRI for targeting biopsy and salvage treatments after prostate cancer recurrence J. Mason 1 , E. Adiotomre 2 , B. Carey 2 , P. Bownes 1 , A. Henry 3 1 Leeds Cancer Centre, Medical Physics & Engineering, Leeds, United Kingdom 2 Leeds Cancer Centre, Radiology, Leeds, United Kingdom 3 Leeds Cancer Centre, Clinical Oncology, Leeds, United Kingdom Purpose or Objective In men with non-metastatic prostate cancer who develop biochemical failure following radiation, multi-parametric MRI (mp-MRI) has an increasing role in targeting biopsies and localising target volumes to allow partial gland salvage treatments. T2 weighted MRI (T2W) and diffusion weighted imaging (DWI) are usually preferred for planning primary treatment but may be less useful after radiotherapy due to radiation induced fibrosis. For I-125 seed implant patients the brachytherapy seeds may create artefact that further reduces the value of DWI. Dynamic contrast enhanced MRI (DCE) demonstrates cancer induced neo-angiogenesis and may be of more value. This study compares T2W, DWI and DCE in patients previously treated with radiotherapy in terms of their usefulness for localising areas of prostate cancer recurrence. Material and Methods From a cohort of 37 patients with template biopsy confirmed local recurrence who were treated with whole or partial gland salvage brachytherapy between 2010- 2017, 19 patients who received mp-MRI scans locally using a consistent imaging protocol were retrospectively assessed. The original primary treatments were either I- 125 seed implant monotherapy (n=15, between 2002- 2013) or radical external beam radiotherapy (EBRT) (n=4, between 2007-2012). A radiologist with >20 years experience of prostate MRI reviewed imaging on two occasions blinded to clinical and biopsy information. At first review the T2W and DWI sequences were assessed for likely presence of tumour and at second review the additional DCE sequence was assessed. Results were recorded and compared on a prostate diagram divided into 12 sectors (quadrants at each of base, mid-gland and apex) plus seminal vesicles (SV). Following this review, results were validated against biopsy information. Results For seed patients, recurrence was visible in 6/15 patients for T2W, 5/15 for DWI and 15/15 for DCE-MRI. For EBRT patients, recurrence was visible in 1/4 patients for T2W, 3/4 for DWI and 4/4 for DCE-MRI. 5/19 patients had recurrence involving the SV and in 2/5 of the cases where recurrence was visible in DWI, the recurrence was in the SV alone. From the sector based analysis, excluding two patients with SV only recurrence, the recurrence involved median 2/12 prostate sectors (range 1/12-5/12) for seed patients and median 6/12 sectors (range 2/12-12/12) for EBRT patients. Combining the results for the 15 seed patients, 12 out of the 27 sectors in which recurrence was detected were at the anterior base of the prostate gland. An example is shown in the figure. Tumour locations determined in this review were later successfully validated against targeted biopsy results