Prognostic significance of partial tumor regression after preoperative chemoradiotherapy for rectal cancer: a meta-analysis.

Abstract

Complete tumor regression after preoperative chemoradiotherapy for rectal cancer has been associated with better disease-free and overall survival. The survival experience for patients with partial tumor regression is less clear. The aim of this meta-analysis was to evaluate the prognostic significance of partial response after preoperative chemotherapy on disease-free survival in rectal cancer patients. Relevant studies were identified by a search of MEDLINE and EMBASE databases with no restrictions to October 31, 2012. We included long-course radiotherapy that reported the association between degree of tumor regression and disease-free survival of rectal cancer. Direct, indirect, and graph methods were used to extract HRs. Study-specific HRs on the disease-free survival were pooled using a random-effects model. Eleven articles in total were selected. Analysis was performed first among the 6 studies that separated partial response from the complete response and later among all 11 of the studies. Pooled HR was 0.49 (95% CI, 0.28-0.85) for the 6 studies that compared partial response with poor response. It was 0.41 (95% CI, 0.25-0.67) when all 11 of the studies were analyzed together. The studies were limited by not being prospective, randomized trials, and the tumor regression grades were not uniform. Partial tumor response is associated with a 50% improvement in disease-free survival and should be considered as a favorable prognostic factor.