Upfront short course radiotherapy (SCRT) in metastatic rectal cancer (mRC): A way forward.

Abstract

3570 Background: To evaluate the feasibility and efficacy of SCRT followed by chemotherapy (CT) in locally advanced metastatic rectal cancer (LAmRC). Methods: Between May 2012 and August 2015, 70 patients having LAmRC with or without circumferential resection margin (CRM) positive disease treated with SCRT (25Gy/5#) followed by 3-6 cycles of capecitabine/5-FU, oxaliplatin or irinotecan based CT were assessed. Results: Fifty one had single site metastases (23 liver, 16 lung, 10 retroperitoneal lymph nodes and 2 peritoneum), 9 had combined lung and liver metastases and 10 had combined nodal and organ metastases. Sixty five (93%) patients could complete planned SCRT and 3-6 cycles of chemotherapy (starting 7-10 days after RT completion) with dose reduction in 21 (32%) patients owing to CT induced toxicities. Local tumor down-staging was achieved in 43 (61.4%) patients and the rest had a stable primary disease. Radiologically, CRM was free in 25 (46.3%) patients out of 54 initially involved. Surgery of the primary was planned in 38 (58%). R0 resection in 26 (40%), R1 in 7 (pCRM positive). Five refused surgery in spite of being resectable. Rest of the 27 (41%) received palliative CT due to progression of distant disease. Metastatectomy along with primary surgery was done in 16 (25%) patients. Median follow up was 29 months. Overall survival (OS) of entire cohort at 2 years was 40%. Median progression free survival (PFS) and OS of patients with resected primary was 17 (10-24) and 37 (28-45) months, respectively, which is significantly better than those who were not resected (p = < 0.001). Of these 33 resected patients, 13 (39.4%) are disease free and 20 have progressed (16 distant, 2 loco-regional and 2 local and systemic). Conclusions: Upfront SCRT followed by systemic CT in an unresectable group of metastatic rectal cancer patients is safe and feasible and is having encouraging results in terms of downstaging and resectability of the primary. [Table: see text]