Adjuvant chemotherapy in older patients with stage II and III colon cancers: Is less more?

Guidelines recommend adjuvant chemotherapy (AC) for patients with high-risk stage II and III colon cancers. However, the use of multi-agent chemotherapy (MAC) in older patients remains controversial. This study aimed to assess whether the survival benefit of single-agent chemotherapy (SAC) and MAC in stage II and III colon cancers diminishes with age.

The National Cancer Database was queried for adults who underwent surgical resection for colon adenocarcinoma from 2010 to 2020. Analysis was divided into 3 groups: low- and high-risk stage II and stage III. Multivariable Cox regression with an interaction term was used to estimate the effect of AC on overall survival (OS) by age (18-69, 70-79, and >80 years).

Of 61 961 patients (30% low-risk stage II, 17% high-risk stage II%, and 52% stage III), most patients with stage II were treated without chemotherapy, whereas >65% of patients with stage III received MAC. In multivariable analysis, chemotherapy's effect on OS did not significantly differ by age. In low-risk stage II, SAC showed a marginal survival benefit (hazard ratio [HR], 0.72; 95% CI, 0.58-0.89), and in high-risk stage II, AC was beneficial, with single agent providing improved benefit over multiagent (HR, 0.70; 95% CI, 0.56-0.87). In stage III, MAC offered improved survival benefit (HR, 0.42; 95% CI, 0.39-0.45).

In this national cohort, age did not significantly affect the survival effect of AC. Although SAC was beneficial in stage II disease, MAC improved survival in stage III. These findings support current guidelines and underscore the importance of individual decision making based on functional status for this population.