Background: 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.
Objective: 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.
Data sources: Relevant studies were identified by a search of MEDLINE and EMBASE databases with no restrictions to October 31, 2012.
Study selection: We included long-course radiotherapy that reported the association between degree of tumor regression and disease-free survival of rectal cancer.
Interventions: Direct, indirect, and graph methods were used to extract HRs.
Main outcome measures: 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.
Results: 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.
Limitations: The studies were limited by not being prospective, randomized trials, and the tumor regression grades were not uniform.
Conclusions: Partial tumor response is associated with a 50% improvement in disease-free survival and should be considered as a favorable prognostic factor.