The survival outcome differs between left-sided colon and middle/low rectal cancer after colorectal hepatic metastasectomy

Introduction The clinical outcomes between left-sided colon cancer and middle/low rectal cancer appear to be different. We aimed to examine the impact of primary tumor location regarding the left-sided colon and middle/low rectum on the overall survival (OS) of colorectal hepatic metastasectomy. Patients and Methods Patients who underwent colorectal hepatic metastasectomy were retrospectively enrolled. Patients were classified into two groups according to primary tumor location (left-sided colon and middle/low rectum). Categorical variables were compared using the chi-square test or Fisher’s exact test, and continuous variables were analyzed using Student’s t-test. Survival was analyzed by the KaplanMeier method and log-rank test. The prognostic factors were analyzed by univariate and multivariate analyses using Cox proportional hazards regression models. Results Totally, 365 patients were enrolled. Patients with left-sided colon cancer had significantly better OS than those with middle/low rectal cancer (hazard ratio (HR) 0.725, P=0.018), with a median OS of 48 months and 38 months, respectively. In the subgroup analysis of RAS mutations, those with left-sided colon cancer had significantly prolonged OS compared to those with middle/low rectum cancer (HR 0.608, P=0.034), with a median OS of 49 months and 26 months, respectively. This observation was limited to patients with RAS mutations. Conclusion According to our findings, middle/low rectal cancer had poorer survival outcome, and should not be categorized together with left-sided colon cancer in terms of OS following colorectal hepatic metastasectomy.