ESTRO 35 Abstract-book

ESTRO 35 2016 S605 ________________________________________________________________________________ EP-1286 Does dose-escalated neo-adjuvant radiotherapy improve pathological response in rectal cancers? N. Pasha 1 Queen's Hospital, Clinical Oncology, Romford, United Kingdom 1 , D. Woolf 1 , M. Martinou 1 , K. Williams 1 , S. Ball 1 , S. Raouf 1 Purpose or Objective: Early proctoscopy (1 year) can predict late rectal mucosa changes and therefore can be used as surrogate end-point for late rectal toxicity. The aim of this study was to retrospectively analyze data of patients treated at a single institution, consecutively enrolled in different prospective clinical trials, trying to determine a correlation between treatment parameters and VRS (Vienna Rectoscopy Score) recorded at 1-year proctoscopy.

Purpose or Objective: Neoadjuvant chemoradiotherapy (CRT) is considered a standard approach for locally invasive rectal cancer. Several phase 3 studies have shown an improvement in local control with combined radiotherapy and capecitabine / 5-fluorouracil. There is good evidence that increased dose of radiotherapy is associated with both better pathological response and survival in many malignancies, although the data in rectal cancer is less convincing. In this study we assessed the impact of dose- escalated radiotherapy on pathological outcome. Material and Methods: We evaluated all patients who received chemo-radiotherapy for rectal cancer and subsequently had an anterior resection/ abdominoperineal resection with a total mesorectal excision (TME) between February 2012 and December 2014. Patients received 50.4Gy 1.8Gy fractions, and more recently those who have T3/4 disease with a threatened circumferential margin had a simultaneous integrated boost of the primary tumour to a total dose of 53.2Gy, with concurrent capecitabine chemotherapy (825mg/m2 BD) daily throughout treatment. Treatment was initially using 3-D conformal radiotherapy but more recently has been using a VMAT technique with cone beam CT used during treatment. Surgery was performed 8-12 weeks after completion of CRT.The primary end point was pathological response (Dworak score 0-4) of the operative specimen. Scores of 0-2 were considered to be non- pathological responders and scores of 3-4 were considered to be pathological responders. Results: A total of 73 patients received neoadjuvant chemoradiotherapy. 61 patients weretreated with a standard radiotherapy fractionation of 50.4Gy in 28 fractions (Group A) and 12 patients were treated with a dose escalated fractionation to the primary tumour of 53.2Gy in 28 fractions (Group B). The rate of pathological response was 39.3% in Group A and 86.7% with Group B (t=3.55, p<0.001). Conclusion: This study demonstrates the beneficial effects of dose-escalated radiotherapy and wetherefore recommend this regime be considered for inclusion in future phase 2 studies. EP-1287 Radiation-induced rectal toxicity in prostate cancer: a proctoscopy evaluation E. Ippolito 1 , M. Nuzzo 2 , G. Macchia 2 , F. Deodato 2 , S. Cilla 3 , M. Ingrosso 4 , L. Fuccio 5 , A. Farioli 5 , G. Mantini 6 , V. Valentini 6 , G.C. Mattiucci 6 , G. Siepe 7 , M. Ntreta 7 , S. Cammelli 7 , A. Guido 7 , M. Pieri 7 , A. Arcelli 7 , F. Bertini 7 , L. Ronchi 7 , A.G. Morganti 7 1 Campus Biomedico University, Radiotherapy Unit, Roma, Italy 2 Fondazione di Ricerca e Cura “Giovanni Paolo II”- Catholic University of Sacred Heart, Radiotherapy Unit, Campobasso, Italy 3 Fondazione di Ricerca e Cura “Giovanni Paolo II”- Catholic University of Sacred Heart, Medical Physics Unit, Campobasso, Italy 4 Fondazione di Ricerca e Cura “Giovanni Paolo II”- Catholic University of Sacred Heart, Endoscopy Unit, Campobasso, Italy 5 Sant’Orsola-Malpighi Hospital- University of Bologna, Department of Medical and Surgical Sciences - DIMEC, Bologna, Italy 6 Policlinico Universitario “A. Gemelli”- Università Cattolica del Sacro Cuore, Department of Radiotherapy, Roma, Italy 7 Radiation Oncology Center- Sant'Orsola-Malpighi Hospital- University of Bologna, Department of Experimental- Diagnostic and Specialty Medicine - DIMES, Bologna, Italy

Material and Methods: Patients with prostate adenocarcinoma treated with curative or adjuvant RT underwent endoscopy one year after RT; 195 patients were included in this analysis. Correlations between VRS > 2 and several treatment parameters were investigated by univariate and multivariate logistic analysis. Results: Patients treated with an EQD2 dose > 75 Gy, with hypofractionatied schedule and radiosurgery boost had a higher incidence of VRS > 2 (p= < 0.001). On the contrary, previous surgery and 3D-conformal radiotherapy (vs IMRT) were associated with a lower incidence of rectal mucosal changes (p=< 0.001; p= 0.003, respectively). At multivariate analysis radiosurgery boost was associated with the highest odd ratios for the risk of developing a VRS > 2 (OR: 4.143; CI: 1.24-13.81; p=0.001). Even surgery showed a significant correlation with VRS > 2 (OR: 0.39; CI: 0.17-9.94; p=0.037, Table 1).

Conclusion: Prolonged patients follow-up is needed to “clinically” confirm the increased rectal toxicity produced by radiosurgery boost. EP-1288 Sphincter function and dose of radiation in rectal cancer. A Single-Institutional study F. Arias 1 , C. Eito 1 , G. Asín 1 , I. Mora 1 , K. Cambra 2 , F. Mañeru 3 , B. Ibáñez 2 , L. Arbea 4 , M. Errasti 1 , M. Barrado 1 , M. Campo 1 , I. Visus 1 , J. García-Escobedo 1 , C. Torres 1 , M. Ciga 5 2 Complejo Hospitalario de Navarra, Statistics Department, Pamplona, Spain 3 Complejo Hospitalario de Navarra, Department of Physics, Pamplona, Spain 4 Clínica Universidad de Navarra, Department of Radiotherapy-Oncology, Pamplona, Spain 5 Complejo Hospitalario de Navarra, Department of Surgery, Pamplona, Spain Purpose or Objective: The objective of the study is to determine the correlations among the variables of dose and the sphincter function (SF) in patients with locally advanced rectal cancer treated with preoperative capecitabine/radiotherapy followed by Local Anterior Resection(LAR) +TME. Material and Methods: We have retrospectively reviewed 92 consecutive patients with LARC treated at our center with LAR from 2006 and more than 1 year free from disease. We re-contoured the anal sphincters (AS) of patients with the help of the radiologist. SF was assessed with the Wexner scale (0-20 points, being punctuation inversely proportional to SF). All questionnaires were filled out between January 2010 and December 2012. Dosimetric parameters that have been studied include: V20 V30, V40, V50, mean dose (Dmean), mínimum dose (Dmin), D90 (dose received by 90% of the sphincter) and D98 Statistical analysis: the correlations 1 Complejo Hospitalario de Navarra, Department of Radiotherapy-Oncology, Pamplona, Spain