Resection after preoperative chemotherapy versus synchronous liver resection of colorectal cancer liver metastases: A propensity score matching analysis

This study aimed to determine the prognostic effects of preoperative chemotherapy for colorectal cancer liver metastasis (CLM). We retrospectively evaluated 2 groups of patients between January 2006 and August 2012. A total of 53 patients who had ≥3 hepatic metastases underwent resection after preoperative chemotherapy (preoperative chemotherapy group), whereas 96 patients who had ≥3 hepatic metastases underwent resection with a curative intent before chemotherapy for CLM (primary resection group). A propensity score (PS) model was used to compare the both groups. The 3-year disease-free survival (DFS) rates were 31.7% and 20.4% in the preoperative chemotherapy and primary resection groups, respectively (log-rank = 0.015). Analyzing 32 PS matched pairs, we found that the DFS rate was significantly higher in the preoperative chemotherapy group than in the primary resection group (3-year DFS rates were 34.2% and 16.8%, respectively [log-rank = 0.019]). Preoperative chemotherapy group patients had better DFSs than primary resection group patients in various multivariate analyses, including crude, multivariable, average treatment effect with inverse probability of treatment weighting model and PS matching. Responses to chemotherapy are as important as achieving complete resection in cases of multiple hepatic metastases. Preoperative chemotherapy may therefore be preferentially considered for patients who experience difficulty undergoing complete resection for multiple hepatic metastases.