ESTRO 36 Abstract Book

S368 ESTRO 36 _______________________________________________________________________________________________

days 1-4, 29-32 and 50-53 and panitumumab on day 1, 15, 29, 50 and 65. The doses were as follows: level -1: 5FU at 400 mg/m 2 /j and panitumumab at 3mg/kg; level 0: 5FU at 600 mg/m 2 /j and panitumumab at 3mg/kg. DLT was defined by febrile neutropenia, neutropenia grade 4, thrombocytopenia grade 4 or grade 3 during more than 1 week, GI toxicity grade ≥ 3, dermatitis grade ≥ 4, first part of treatment non completed (< 75 % doses) according to CTCAEv4, and assessed until 8 weeks after the completion of the treatment Tumor evaluation was performed at 8 weeks, 4 months after end of treatment and every 4 Out of 10 pts enrolled in this study between June 2012 and March 2015, 9 were treated according to the protocol (one patient was excluded before treatment because the dosimetric plan did not meet the dosimetric constraints). Median age was 57.4 years (range: 52.0-71.1). Tumor characteristics were as follows: T2: one patient; T3: 6; T4: 2; N0: 2 and N+: 7 pts. DLT was observed for the first 3 patients at level 0: febrile neutropenia for one patient, thrombocytopenia and diarrhea grade 3 for the second patient and rectitis, cystitis, dermatitis grade 3 for the third patient. Therefore the protocol was amended to withdraw one mitomycin injection. Six patients were treated on level -1. Out of 6 patients, 2 experienced grade 3 toxicities: asthenia and rectitis for one patient and lymphopenia for the second. Treatment was completed for all 6 pts. Considering all patients treated at level 0 and -1, complete response was achieved for 8 pts whereas one experienced a local recurrence 9 months after the end of the treatment and went through abomino-perineal resection. All patients were alive with a median follow-up of 18 months. Conclusion In this phase 1 trial, panitumumab (3 mg/kg), mitomycin (10 mg/m²) and 5FU (400 mg/m²/day) were considered as the tolerable and active doses. These are the recommended doses for the ongoing phase II trial (EudraCT number: 2011-005436-26). PO-0703 Bowel dysfunction resulting from different treatment strategies in patients with rectal cancer. T. Vuong 1 , A. Garant 2 , S. Devic 3 , A. Kezouth 4 1 Jewish General Hospital - McGill University, Radiation Oncology,Montreal, Canada 2 McGill University, Radiation Oncology, Montreal, Canada 3 Jewish General Hospital- McGill University, Radiation Oncology, Montreal, Canada 4 Jewish General Hospital- McGill University, Statistics- Epidemiology, Montreal, Canada Purpose or Objective For patients with rectal cancer, sphincter preservation surgery total mesorectal surgery (SPS-TME) is a most important treatment goal after cure. However, beside the body image preservation, bowel function is a major outcome with important impact on quality of life. The Low Anterior resection syndrome (LARS) is well documented with bowel frequency, urgency, clustering, stool and gaz incontinence. A validated LARS questionnaire documented a 40% of severe LARS score after TME alone and 60% after pre-operative Radiation (RT) and TME. In this study, we are proposing to evaluate our population of patients with ano-rectal cancer with various RT regimens. Material and Methods Patients with rectal cancer or anal canal cancer treated between 2013 - 2015 were recruited in this study. IRB approved signed consent was obtained with self administered questionnaires at least in two point times. Patients with LAR with ileostomy closure for at least 3 months. Patients with anal canal treated with chemotherapy (CT) and RT and rectal cancer treated with External beam (EBRT) and high dose rate brachytherapy months. Results

(HDRBT) but with no evidence of local recurrence.

Results Patients and tumor characteristics and LARS scoring results by treatment regimen are shown in the Table1 and Figure 1. For the initial 3X4 cross-classified table (3 category-scores: No Lars, Minor Lars, Major Lars, 4 treatment groups: HDRBT-TME, CT-RT-TME , CT-RT (No surgery), EBRT + HDRBT (No surgery)),we computed the Fisher exact test .There is independence between the score category and the treatment group with a p-value of 0.4538. We also considered the Lars score as a continuous variable and we performed an ANOVA which resulted in a non-statistical difference between the score means of the 4 treatment groups. Finally to study the severity of the disease we dichotomized the Lars score into subjects with Lars score <=26 and those >=27 to construct a new 2X4 table. We found a statistical an overall statistical difference between the 4 groups with a p-value of 0.0270.Performing a multiple comparison test, an analogous of a Tukey-type multiple comparison test, we concluded that there is a statistical difference between CT-RT and TME and EBRT + HDRBT (No surgery) group, namely we have more subjects with major Lars in group CT-XRT + TME than group EBRT-HDRBT (No surgery).

Conclusion In this study, using the LARS scoring questionnaire, the favorable functional bowel results (lowest rate of severe LARS score) in patients treated with EBRT-HDRBT and no surgery, in the organ preservation approach compared to standard CT-RT and surgery, support the present efforts in developping in organ preservation trials for patients with operable rectal cancer. PO-0704 Circulating angiogenesis factors predicting poor chemoradiotherapy outcome in rectal cancer S. Meltzer 1,2 , L.G. Lyckander 3 , A.H. Ree 1,2 , K.R. Redalen 1 1 Akershus University Hospital, Department of Oncology, Lørenskog, Norway 2 University of Oslo, Institute of Clinical Medicine, Oslo, Norway 3 Akershus University Hospital, Department of Pathology, Lørenskog, Norway Purpose or Objective Rapid advances in personalised cancer treatment increase the demand for early stratification of tumours and their hosts, which requires easy-to-use, easy-to-interpret biomarkers to assess tumour phenotypes. In this context,