ESTRO 36 Abstract Book

S689 ESTRO 36 _______________________________________________________________________________________________

surgery. In order to identify prognostic factors, we analyzed T and N characteristics at diagnosis and at restaging (before surgery) and their variations (based on MR-images). We also analyzed age, sex and pathological characteristics (surgical approach, ypT, ypN, number of nodes removed, nodal ratio considered as N+/Nresected, histological mucinous aspect, grading, margins, Quirke grade andDworak’s tumor regression). Results All pts completed planned RT-CT. The OS at 2 and 5 years was 97,3% and 88,5%, respectively; 2 and 5 years DFS was 91,5% and 77,5%, respectively. In the multivariate analysis the statistically significant prognostic factors related to DFS were: T-volume (p= 0,046), number of involved quadrants (p= 0,011), distance between T and mesorectal fascia (p= 0,015), pT (p= 0,001), pN (p<0,001), nodal ratio (p<0,0001) and TRG (p= 0,001). Regard to OS, the statistically significant prognostic factors were: number of involved quadrants (p= 0,011), pN (p= 0,009), number of resected nodes (p= 0,042) and nodal ratio (p= 0,002). Conclusion Analyzing our data, we could conclude that clinical T- parameters, pathological T stage and pathological N- parameters are strongly related to an higher incidence of local and distant relapses (DFS). Regard to OS, clinical T- parameters and pathological N-parameters are singnificantly correlated, while pathological T stage does not seem to have a role as prognostic factor. A better knowledge of these factors related to local and distant relapses will be necessary to decide whether intensify local or systemic treatments. EP-1283 Short Course Radiation Therapy For Locally Advanced Rectal Cancer J. Casalta Lopes 1 , A. Ponte 1 , I. Nobre-Góis 1 , T. Teixeira 1 , M.R. Silva 2 , M. Borrego 1 1 Centro Hospitalar e Universitário de Coimbra, Radiation Oncology, Coimbra, Portugal 2 Centro Hospitalar e Universitário de Coimbra, Pathology, Coimbra, Portugal Purpose or Objective v Locally advanced rectal carcinoma (LARC)v is usually treated with radiotherapy (RT) followed by svurgery. One of the schemes is short course RT (SC: 25Gy / v5 fractions / 1 week) historically followed by immedviate surgery. Studies show that a longer interval between SC-RT and surgery may increase downstaging, with the acceptance of this approach in published international guidelines. Intervals from 1 to 4 weeks are associated with higher rates of postoperative complications. In this study we aim to evaluate toxicity, response to treatment and survival in patients with LARC treated with SC-RT in the neoadjuvant setting. Material and Methods Prospective inclusion of patients with LARC treated by SC- RT between 2002 and 2015. Response was assessed by pathological stage and Ryan modified tumor regression grade (TRG); toxicity was evaluated using CTCAE 4.0 scale. Survival curves were estimated using Kaplan-Meier’s method. A type I error of 0.05 was considered. Results 73 patients included, 63.0% male. Median age was 80 years, 31.5% with Karnofsky index lesser or equal to 80%. Tumor stage was cT3 in 80.9% and cT4 in 15% of patients; 58.9% were cN+. Perineal acute toxicity grade 2 was described in 2.7%, with no other toxicities. 68 patients underwent surgery with a median RT-surgery interval of 7 weeks (1-22 weeks). Conservative surgery was performed in 79.4% and postoperative complications observed in 33.8%. Complete pathological response (cPR) achieved in 7.4% of patients with TRG 0-1 in 8.9%. Lymphovascular

Conclusion The SIB/VMAT schedule is well tolerate in LARC. The toxicity was well manageable and the prescribed dose is delivered. Despite the few numbers of patients the rate of pCR is promising. Longer follow-up is required for survival outcomes. EP-1282 Clinical and pathological prognostic factors in locally advanced rectal cancer (larc) S. Montrone 1 , A. Sainato 1 , R. Morganti 2 , C. Vivaldi 3 , C. Laliscia 1 , B. Manfredi 1 , G. Coraggio 1 , M. Cantarella 1 , G. Musettini 3 , D. Delishaj 1 , E. Lombardo 1 , A. Cristaudo 1 , F. Orlandi 1 , G. Masi 3 , P. Buccianti 4 , A. Falcone 3 , F. Pasqualetti 1 , F. Paiar 1 1 OSPEDALE SANTA CHIARA, Radiotherapy, PISA, Italy 2 OSPEDALE SANTA CHIARA, Oncology- Biostatistical Consulting, PISA, Italy 3 OSPEDALE SANTA CHIARA, Oncology, PISA, Italy 4 OSPEDALE CISANELLO, Colon-rectal Surgery, PISA, Italy Purpose or Objective Colorectal cancer is the most common gastrointestinal malignancy. More than half of rectal cancer patients (pts) have a LARC at diagnosis and preoperative RT-CT followed by total mesorectal excision (TME) is the standard of cure in these pts. Many studies have analyzed clinical and pathological parameters that could be considered as prognostic factors in pts with rectal cancer. This study aim to identify prognostic factors related to OS and DFS in pts affected by LARC and treated in Pisa University Hospital between January 2008 and April 2014. Material and Methods We analyzed retrospectively the data of 119 pts affected by LARC treated with neoadjuvant RT-CT (50.4 Gy in 28 FF + capecitabine 1650 mg/mq/day) followed by TME-