ESTRO 36 Abstract Book

S682 ESTRO 36 2017 _______________________________________________________________________________________________

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- 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

Thirty-nine pts treated from May 2015 to February 2016 were included in this analysis. The median age was 64 years [range 44-77years]; Male-Female ratio was 2.2. Clinical involvement of mesorectal fascia was detected in 18 pts (46%). CTV2 included always presacral space and internal iliac nodes, in 30 pts (77%) and in 4 pts (10%) the obturator nodes and the external iliac nodes were added, respectively. 5 pts received CT in the pre-surgical pause. 38 pts received a Total Mesorectal Excision surgery (69% Anterior Resection and 26% Abdominal-Perineal Resection), in 2 pts (5%) a WW approach was preferred. Adjuvant CT was administered to 18 pts. The radiation prescribed dose was entirely delivered in all pts. GI toxicity was recorded in 31 pts (79%): diarrhea and proctitis were most detected. Four cases of grade 3 GI toxicities were registered (6% of all GI toxicities). GU and HE toxicities were less frequent: non infective cystitis (13 pts) and neutropenia (6 pts) were observed. However, none of them presented a toxicity grade≥ 3. About CT, 8 pts (20%) received less than 4 cycles of concomitant CT because of HE or GI toxicity. pCR was achieved in 10 pts (26%). TRG grade 1 2 3 and 4 was recorded in 11 (28%), 8 (20.5%), 13 (33%) and 5 (13%), respectively. At the median follow-up of 18 weeks the local control, the disease-free survival and the overall survival rates were 100%, 92% and 97%, respectively.

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)