ESTRO 2020 Abstract book

S633 ESTRO 2020

diarrhoea, constipation, sexual issues, and rectal incontinence, bleeding and urgency. Primary descriptive toxicity analysis was followed by comparison (Chi-square test) between older patients (>65 years-old) and younger, for the most frequent toxicities. The IBM SPSS v.25 software was used for statistical analysis. Results Patient, tumour, and treatment characteristics are listed on Table 1. Median follow-up time was 29 months (IQR 28). Most frequent acute toxicities in the cohort were asthenia (4.5%), pain (20.3%), haematological (3.8%), urinary symptoms (16.2%), constipation (8.2%), diarrhoea (35.4%), and rectal incontinence (3.4%) and bleeding (18.2%). There were no reported cases of anorexia, insomnia, or nausea/vomiting. Patients over 65 y/o had significantly higher rates of urinary symptoms (p=0.026) and haematological toxicity (p= 0.026). They also tend to have more frequent diarrhoea (p=0.245), pain (p=0.129), and rectal incontinence (p=0.056), although not statistically significant. Subsequent classification of the urinary symptoms accordingly with GU-RTOG, showed no patients with grade 3, and non-significant difference between age groups (p=0.576). In relation to late toxicities, the most prevalent in this cohort were fibrosis (19.2%), urinary symptoms (11.7%), diarrhoea (18.2%), rectal incontinence (3.8%), constipation (2.7%) and sexual issues (5.5%). For 19 patients the data related to late toxicity was missing. Sub- group analysis comparing older adults with younger ones showed no significant differences on late toxicity rates.

PO-1108 SCRT and chemotherapy vs LCRT for unresectable rectal cancers. A propensity matched- pair analysis R. Engineer 1 , A. Saklani 2 , A. D'souza 2 , S. Mokal 3 , A. Dhyani 1 , S. Chopra 1 1 Tata Memorial Hospital, Radiation Oncology, Mumbai, India ; 2 Tata Memorial Hospital, Surgical Oncology, Mumbai, India ; 3 Tata Memorial Hospital, Statistics, Mumbai, India Purpose or Objective There is emerging evidence that Neoadjuvant short course Radiotherapy (SCRT) followed by few additional cycles of chemotherapy is equivalent to neoadjuvant long course radiotherapy (LCRT) in patients with locally advanced rectal cancer. We aimed at comparing clinical outcomes of both these approaches in this study. Material and Methods From the prospective database (June 2011 to April 2018), a propensity score was used to match 65 patients with rectal cancer receiving SCRT to 65 patients receiving LCRT. Patients SCRT of 5x5 Gy was followed with 2-3 cycles of capecitabine or Capecitabine + Oxaliplatin chemotherapy. LCRT was 50Gy over 25 fractions with concurrent Capecitabine 825 mg/mt2 b.i.d. Propensity score matching was used to match the data on baseline covariates location of tumor, Differentiation on histology, CRM status on MRI using 1:1 nearest matching and 0.2 Patient and clinical tumor characteristics were similar between groups. CRM was involved in 74% of patients. Majority tumors were large and fixed clinically and were deemed unresectable. R0 resection rate was similar in both the groups. LCRT vs SCRT (73.8% vs 77%; P = 0.52). Pathological complete response was also similar (25% vs 17% p=0.35) The loco regional failures were seen in 20% with LCRT vs 24% in SCRT groups. The median follow up of 44 months for LCRT vs SCRT, the 3 year DFS was (45.4 %vs.42.4, p_0.27) and OAS (60.6% vs. 67.2%, p_0.94) was similar in both the groups. Conclusion In this analysis, LCRT was equivalent to SCRT in terms of tumor response to neoadjuvant therapy, disease free, and overall survival. These findings provide evidence that SCRT followed by chemotherapy has similar oncological outcomes compared to LCRT in locally advanced initially unresectable rectal cancers. PO-1109 Radiotherapy toxicity in older patients with rectal cancer E.D. Rodrigues Pinto 1 , F.A. Lima Aires 1 , M.M. Araújo Reis Lima Marques 1 , M.G. Pinto 1 1 Centro Hospitalar Universitário de São João, Radiotherapy, Porto, Portugal Purpose or Objective The main purpose of this study was to evaluate the radiotherapy (RT) toxicity patterns in older patients (>65 years-old) with rectal cancer. Material and Methods This retrospective study was based on RT Department electronic health records collected on February 2019. This study was approved by the institutional ethical review board. All patients with rectal cancer treated with RT between January 2013 and December 2017 were included (n=291). Patient, tumour, and treatment characteristics were collected. Acute toxicity data related to asthenia, anorexia, pain, insomnia, haematological, any urinary symptoms, nausea/vomiting, diarrhoea, constipation, rectal incontinence, bleeding, and urgency was registered. Acute low gastrointestinal, genitourinary, and skin toxicity were graded according with RTOG. Late toxicity patterns were evaluated through fibrosis, urinary symptoms, caliper. Results