Does adjuvant chemotherapy improve survival in stage II colon cancer?

In patients with stage II colon cancer, individuals with a right-sided colon cancer (RSCC) appear to have a better prognosis than those with a left-sided colon cancer (LSCC), reveals a recent study. Additionally, adjuvant chemotherapy (ACT) falls short of improving cause-specific survival (CSS) in patients with either RSCC or LSCC.

“Even in patients with parts of high-risk features, ACT still did not improve CSS, except for T4 stage LSCC,” the investigators said.

This study identified patients with stage II colon cancer, aged 20‒49 years, using the Surveillance, Epidemiology and End Results (SEER) database. The investigators used both Cox proportional hazards regression, Kaplan-Meier survival analysis, and propensity score matching.

A total of 5,633 patients met the eligibility criteria. Patients with RSCC tended to Black, male, younger, have a poor grade and histologic type, have a larger tumour size, and have more regional nodes examined.

After propensity score matching, patients with RSCC showed significantly better CSS than those with LSCC (hazard ratio [HR], 0.80, 95 percent confidence interval [CI], 0.68‒0.95; p=0.01).

Patients with LSCC, however, did not derive any survival benefit from ACT (HR, 1.10, 95 percent CI, 0.90‒1.35; p=0.35). Furthermore, ACT appeared to cause more harm in patients with RSCC (HR, 1.31, 95 percent CI, 1.05‒1.63; p=0.02).

Likewise, ACT did not improve CSS in patients with high-risk features such as T4 stage and regional nodes examined in both groups, except for those with T4 stage LSCC (HR, 0.65, 95 percent CI, 0.44‒0.97; p=0.02).