Does delaying adjuvant chemotherapy after curative surgery for colorectal cancer impair survival? A meta-analysis.

Abstract

e14021 Background: In stage III colorectal cancer (CRC), adjuvant chemotherapy (CT) is usually prescribed within two months after curative surgery. Whether or not delaying initiation of CT affects survival is still debated. Methods: We performed a meta-analysis (MA) of all published studies (full papers or abstracts) comparing delayed CT with standard care. Studies were obtained from a PubMed query (keywords: CRC, adjuvant treatment, delay of CT), a review (Chau et al, 2006), cross-checking references, and abstracts from the proceedings of ASCO, ASCO GI and WCGI annual meetings. We chose a cut off delay of 8 weeks. Risk ratios (RRs) were calculated from the recorded events (deaths, relapses). We used EasyMA software (fixed-effect model). Results: Fourteen studies (including 4 abstracts) were identified (17,645 patients; 5,952 males, 5,151 females, mean age 70 years). Of these, 3 could not be statistically analysed and 3 used another cut off (4, 5 or 6 weeks), leaving 8 studies for main MA (13,158 patients, 3,932 males, 3,644 females, 5,942 missing data; 5,576 colon cancers, 6,677 rectal, 1,265 missing data). Delaying CT more than 8 weeks was associated to worse overall survival (OS) (RR: 1.20; 95% confidence interval [1.15-1.26]). In the MA including all studies whatever their cut off, longer delay was similarly associated to a worse OS but not a worse relapse-free survival (5 studies). Conclusions: Adjuvant chemotherapy should be started within 8 weeks after surgery. Delaying initiation of adjuvant CT more than 8 weeks after surgery significantly decreased OS but not RFS. This discrepancy might be due to factors not directly related to cancer (postoperative complications, social status) or to a more accurate appraisal of death. No significant financial relationships to disclose.