Impact of primary tumor location on the overall survival of patients with stage IV colorectal cancer: a propensity score analysis of data from the surveillance epidemiology and end results program data

There is an ongoing debate as to whether right-sided versus left-sided tumor location itself represents an independent prognostic factor for patients with stage IV colorectal cancer. Patients with stage IV colorectal cancer were identified from the Surveillance, Epidemiology, and End Results (SEER) database (2004-2013). Both univariate and multivariate Cox regression analyses as well as propensity score matching were used. Overall, 45,471 patients 15,239 (33.5%) with right-sided, 27,314 (60.1%) with left-sided colorectal cancer, and 2918 (6.4%) with cancer of the transverse colon; median follow-up of 17 (months) were eligible. Multivariate analysis showed that patients with right-sided colorectal cancer had worse overall and cancer-specific survival compared to patients with left-sided colorectal cancer. According to results from propensity score matching, prognosis for patients with right-sided carcinomas was showed worse overall and cancer-specific survival. In a population-based series of patients with stage IV colorectal cancer, patients with right-sided tumors exhibited inferior survival.