The assessment of adjuvant chemotherapy benefits after D3 lymphadenectomy in patients with colon cancer: a propensity score matching study

Purpose: Adjuvant chemotherapy (AC) for stage III disease is recognized as a standard treatment and is routinely performed in patients with colon cancer (CC). However, the recommendation for AC is mainly based on studies performed in past environments, where D3 lymphadenectomy was not routinely performed.

Methods: We retrospectively analyzed CC patients who underwent curative resection with D3 lymphadenectomy in Keio Surveillance Epidemiology and End Results (K-SEER) database. After patients were divided into AC and non-AC groups, propensity score matching (PSM) was performed to match the two groups.

Results: After PSM, 84 patients were included in each group. There were no significant differences between the AC and non-AC groups in the 5-year cancer-specific survival (CSS; 88.01% vs. 81.46%, p = 0.295) and 5-year recurrence-free survival (RFS; 69.57 vs. 70.08%, p = 0.820), respectively. In the subgroup analysis, AC improved both the CSS [hazard ratio (HR)0.273; 95% confidence interval (CI) 0.094-0.797, p = 0.017] and RFS (HR 0.376; 95% CI 0.174-0.806, p = 0.012) only for tumors with N2 disease compared to non-AC.

Conclusion: The current indications for AC in patients with CC after D3 lymphadenectomy should be reconsidered. It is possible that AC is appropriate only for stage III CC patients with N2 disease.