Abstract
BackgroundMost previous studies compared survival between left-sided and right-sided colon cancer without adjustment for clinicopathological parameters. We investigated the effect of sidedness on survival among patients with early-stage colon cancer, using a propensity score matching method.MethodsThe 18 registry custom data within the SEER database were used to identify patients who were diagnosed with colon cancer between 2010 and 2014. A propensity score matching analysis was performed using the nearest neighbor method. Survival was estimated using the Kaplan–Meier method. A Cox proportional hazards model was applied to determine the prognostic factors.ResultsIn the unmatched cohort, 25,094 (35.72%) patients were diagnosed with left-sided colon cancer and 45,156 (64.28%) with right-sided colon cancer. After propensity score matching, each cohort included 5118 patients, and the clinicopathological characteristics were well balanced. In the unmatched cohort, left-sided colon cancer had superior all-cause (χ2=315, P<0.01) and cancer-specific (χ2=43, P<0.01) survival than right-sided tumors. However, in the matched cohort, no difference was observed for all-cause (χ2=0.7, P=0.4) and cancer-specific (χ2=0, P=0.96) survival between left and right colon cancer. The Cox model did not indicate sidedness as a prognostic factor. In the subgroup analysis, stage II right-sided colon cancer had a better survival outcome, while stage III left-sided tumors had a better survival outcome.ConclusionsAfter adjusting for clinicopathological characteristics in this study, sidedness showed no impact on survival in early-stage colon cancer. However, sidedness was associated with prognostic differences in stages II and III early-stage colon cancer.
Highlights
Most previous studies compared survival between left-sided and right-sided colon cancer without adjustment for clinicopathological parameters
The primary tumor location in metastatic colon cancer has gradually become a significant factor to be integrated into the treatment plan, with evidence from post hoc analyses of clinical trials and meta-analysis indicating that sidedness in metastatic colon cancer is a strong prognostic parameter [1,2,3]
Most studies based on the Surveillance, Epidemiology and End Results (SEER) database did not achieve a balance of clinicopathological characteristics before performing survival analyses between left- and right-sided colon cancer
Summary
Most previous studies compared survival between left-sided and right-sided colon cancer without adjustment for clinicopathological parameters. We investigated the effect of sidedness on survival among patients with early-stage colon cancer, using a propensity score matching method. Several studies have investigated the impact of sidedness on survival among patients with early-stage colon cancer but have reported inconsistent results [6,7,8,9]. The prognostic value of sidedness in studies which reported a difference is conflicting, and a subgroup analysis based on stage showed a prognostic difference. Most studies based on the Surveillance, Epidemiology and End Results (SEER) database did not achieve a balance of clinicopathological characteristics before performing survival analyses between left- and right-sided colon cancer
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