Adjuvant chemotherapy decision-making in stage II colon adenocarcinoma associated with patients' age and high-risk factors.

PURPOSE: To clarify whether the combination of age and high-risk factors (HRFs) was preferable for adjuvant chemotherapy (AC) decision-making in patients with stage II colon adenocarcinoma.

METHODS: We conducted a retrospective study analyzing eligible colon cancer patients from the Surveillance, Epidemiology, and End Results (SEER) database between 2010 and 2017. A nomogram was used to predict patient prognosis. Decision curve analysis (DCA) predicted model clinical benefit. Restricted cubic spline calculated the optimal cut-off value.

RESULTS: A total of 8570 patients with stage II colon adenocarcinoma were included in this study; 25.2% received AC. A nomogram predicting the prognosis of patients with stage II colon adenocarcinoma was constructed with age and HRFs, and scores were assigned to the relevant variables. DCA showed that age combined with HRFs was superior to treatment decision-making based on HRFs alone. Patients were grouped according to their total score with the cut-off value of 100. AC did not significantly improve overall survival (OS) in low-score group (hazard ratios (HRs) 1.01, 95% confidence intervals (CIs) 0.86-1.18, p = 0.918). In high-score group, AC improved 5-year OS by about 7.6% (HR 0.73, 95% CI 0.61-0.88, p = 0.001). And high-score group mainly included patients aged < 50 years with two or more HRFs and patients aged ≥ 50 years with at least one HRF.

CONCLUSION: Age and HRFs could be preferable for determining the group of stage II colon adenocarcinoma patients who would benefit from AC. Patients aged < 50 years with two or more HRFs might be a potential benefit population for AC.