638 - Watchful Waiting is Safe Following Long Course Chemoradiation for Locally Advanced Rectal Cancer in Patients who have a Complete Clinical Response

Abstract

ABSTRACT Introduction Pre-operative long course chemoradiation (LCRT) has been shown to improve rates of clear surgical resection margins in the treatment of locally advanced rectal cancer. The aim of our study was to compare patient and tumour demographics and outcome in patients who had a complete response (Group A) to pre-operative long course chemoradiation (LCRT) to those that did not have a complete response (Group B) in MRI-staged locally advanced rectal cancer treated at the Royal Devon and Exeter Hospital. Methods Retrospective review of patients treated with LCRT for locally advanced MRI-staged rectal cancer from 2004-2009. Results Fifty-nine patients were reviewed. 13 (22%) Group A and 46 (78%) Group B. Group A had a median age 64 (range 50-77) and Group B 65 (range 38-78). Of 13 complete responders 6 underwent surgery and 7 were kept under close observation. 2 of these 7 subsequently had surgery at 24 and 41 weeks respectively. 5/13 (38.5%) have avoided local surgery to date. All 13 patients are alive with median follow up of 46 months (range 35-88). One developed metastatic disease with both liver and lung metastasis, which have been resected and patient is currently disease-free. 45 of the 46 incomplete responders have been followed up; 22 (48%) have died. 17 (37%) died with cancer, 14 (30%) developed distant recurrence, 5 (11%) local recurrence, 1 (2%) distant and local recurrence and 2 (4%) were inoperable post-LCRT. Discussion Watchful Waiting is a safe and effective option for patients following LCRT for locally advanced rectal cancer who have a complete clinical response to treatment and this avoids surgical morbidity. In terms of patient and tumour demographics both groups were comparable. We suggest that biological tumour factors play the determining role in a patient's response to LCRT and this area requires further investigation to determine who may undergo a complete response. Group A (%) Group B (%) T stage T2 0 3 (6.7) T3 10 (77) 36 (80) T4 3 (23) 6 (13.3) N stage N0 4 (31) 7 (15) N1 4 (31) 12 (27) N2 5 (38) 26 (58) Sex Male 11 (85) 36 (78) Female 2 (15) 10 (22) Tumour height Low 11 (85) 30 (65) Mid 2 (15) 12 (26) Upper 0 4 (9) Disclosure All authors have declared no conflicts of interest.