Overuse and Limited Benefit of Chemotherapy for Stage II Colon Cancer in Young Patients

Few studies have confirmed a benefit for adjuvant chemotherapy (aCTX) in stage II colon cancer. We used the National Cancer Database to explore the use and efficacy of aCTX in patients with both normal-risk (NR) and high-risk (HR) young stage II colon cancer.

We identified patients with stage II colon cancer who underwent colectomy between 2010 and 2015. HR patients included at least: lymphovascular or perineural invasion, < 12 lymph nodes, poor/un-differentiation, T4, or positive margins. Rates of aCTX by age and risk were calculated, and adjusted factors associated with aCTX were identified. Overall survival was estimated using the Kaplan-Meier method and Cox multivariable analyses for patients < 50 years.

Among the 81,066 stage II patients who underwent colectomy, 6093 (7.5%) were < 50 years old. Of these, 2669 patients were HR. Thirty percent of NR and almost 60% of HR patients < 50 years received aCTX, compared with 8% and 23% of patients > 50 years (P < .001). In NR patients < 50 years, 35.3% with microsatellite-stable tumors and 18% with microsatellite unstable tumors received aCTX (P < .001), whereas 63.6% and 43.2%, respectively, of HR patients did (P < .001). The most significant multivariable predictors of aCTX were risk status and age. On univariate analysis, there was no survival benefit associated with aCTX in patients < 50 years. Multivariate analysis failed to demonstrate a survival benefit for aCTX for either group (HR, 0.97; P = .84; NR, 0.1.03; P = .90).

Young patients with HR and NR colon cancer received aCXT more frequently than older patients with no demonstrable survival benefit. This bears further evaluation to avoid the real risks of over-treatment in this increasing population.