Abstract book - ESTRO meets Asia

S96 ESTRO meets Asia 2018

Purpose or Objective To evaluate patient characteristics and immediate post treatment responses in predicting disease free survival in patients with Carcinoma rectum treated with neo- adjuvant chemo-radiation. Material and Methods An audit of patients with biopsy confirmed Carcinoma rectum treated with neo-adjuvant chemo-radiation between 2009- 2017, was undertaken. Radiation dose ranged between 45-50.4 Gray delivered in 25-28 fractions with concurrent Fluorouracil/ Capecitabine based chemotherapy Results A total of 87 patients formed the study cohort. 86% patients were male and 14% were females. Hypertension was the most common comorbidity (23%) followed by Diabetes (18%). 8% patients had smoking/alcohol addictions, 4% had a first degree relative with cancer history and 2% had a past history of ulcerative colitis. 75%, 13.6%, and 11.4 patients showed involvement of distal, middle and upper rectum respectively. Pre-treatment staging was done clinically in conjunction with radiological investigations. 18% were stage II and 77% were stage III (9% IIIA, 65% IIIB, 3% IIIC). Immediate post treatment effect was evaluated with Imaging including CT/PET/MRI 6-8 weeks post chemo-radiation as well as histopathology report post surgery. 82% patients were successfully down- staged post treatment. 88% patients underwent surgery (59.4% were APR/colectomy and 22.9% were LAR, out of which 45% patients had cancer involving the distal rectum). Reasons for non-operability included disease progression post neo-adjuvant treatment, metastasis at presentation, tuberculosis, and intra-operative dense adhesions. 6% were lost to follow up. 10.3 % patients achieved good to complete radiological as well as pathological response out of which 66% patients had a mean disease-free survival of 18 months (Range- 10 months to 6.5 yrs). 13.45% patients had local recurrence and risk factors for the same included age<45, recurrent at presentation, no to minimal radiological/pathological response to treatment, high post treatment CEA >4 and Presence of lympho-vascular invasion. 20% patients had biopsy confirmed distant metastasis in the lung (58.8%) and liver (47%). Acute grade 3 toxicities were observed in 17% patients (skin- 90%, Gastrointestinal- 46.6% and hematology- 13.3%). No grade 4 toxicities were recorded. Chronic toxicities included radiation proctitis and levator ani fibrosis, recorded in 3.6% patients. 2 deaths were recorded due to co-morbid conditions (uncontrolled diabetes and cardiac failure) Conclusion Majority of the patients were stage III or higher and non resectable at presentation and neo-adjuvant treatment successfully down-staged the disease in more than 80% patients. Poorer outcomes were observed in young age groups, and in patients who showed no to minimal radiological as well as pathological response to neo- adjuvant treatment. Conversely, a collective good to complete radiological and pathological response predicted a high DFS in two-thirds of the study cohort PO-234 Endorectal brachy boost to increase tumor response for non-operative management of rectal cancers R. Engineer 1 , M. Patil 2 , S. Lewis 2 , S. Chopra 2 , S. Dheera 2 , A. D'Souza 3 , V. Ostwal 4 , P. Patil 5 , A. Saklani 3 1 Tata Memorial Hospital, Radiation Oncology, Mumbai, India 2 Tata Memorial Centre, Radiation Oncology, Mumbai, India 3 Tata Memorial Centre, Surgical Oncology, Mumbai, India 4 Tata Memorial Centre, Medical Oncology, Mumbai, India

5 Tata Memorial Centre, Gastroenterology, Mumbai, India Purpose or Objective About 15-30% of cases diagnosed with rectal cancer achieve complete clinicoradiological response and can be offered no- operate management. This study explores the possibility of increasing the primary tumor response by increasing the dose of Radiotherapy by high dose rate (HDR) endorectal boost. Material and Methods Sixteen patients diagnosed with locally advanced rectal cancers treated between October 2017 and March 2018 were included. All were staged with pelvic MRI and CECT of Thorax and abdomen. All had low lying rectal cancers (<6cm from anal verge) and less than 2/3 rd of circumferential involvement. External beam RT (EBRT) was given using 3DCRT or IMRT technique over 5 weeks. Post EBRT all the patients were planned to receive endorectal brachytherapy by a customized applicator (multichannel) at the median time of 10 days after completion of EBRT. Brachytherapy planning was done using pelvic MRI with brachytherapy applicator in situ. Gross tumor volume or residual tumor was delineated on MRI. The dose delivered to the GTV was 4-6Gy with HDR. The GTV was covered with minimum 85% of the isodose at the periphery. The second fraction was delivered after 7 days using the same plan. Response to the tumor was evaluated after 6 weeks post last dose of brachytherapy. If there was a good response the patients were re-evaluated after 6 weeks with MRI pelvis, endoscopy and digital rectal examination and if found to be having near complete (nCR i.e.<2cm residual lesion or scar) or complete clinical response (cCR) were offered wait and watch management. Patients with partial response (PR) or less, at 12 weeks post RT were offered Patient’s characteristics are shown in Table 1. Eleven patients received a total of 63Gy (EQD2) whereas 5 patients received 59Gy (EQD2). For brachytherapy depth of prescription varied from 6mm to 10mm (median 8mm) Fig 1. Post brachytherapy at 12 weeks, 5 (31%) patients had cCR, 5 (31%) had nCR and 6 (38%) had PR. At the median follow up of 16 (11-31) weeks, 4 (25%) patients underwent surgery (APR), of these 1 patient had pCR, 1 (pT2N0) 1 (pT3 N0) and (1 pT3 N2) on histopathology. Rest of the 12 (75%) patients continue to be on wait and watch protocol. surgery. Results

Conclusion MR guided brachytherapy post EBRT is promising approach to increase the number of clinicoradiologic response thereby avoiding surgery in a large number of carefully selected cases.