Survival rates for stage II colon cancer patients treated with or without chemotherapy in a population-based setting

Background and aims There is considerable uncertainty as to whether adjuvant 5-fluorouracil-based chemotherapy provides survival benefit for colon cancer patients with stage II disease. Consequently, the current rates of chemotherapy use for this disease are low despite 5-year survival rates of only 70-80%. The aim of the present study is to compare the survival rate of stage II colon cancer patients treated by surgery alone with that of patients also treated by chemotherapy. Patients and methods A population-based observational study was conducted on the survival of stage II colon cancer patients (n = 812) diagnosed in Western Australia from 1993 to 2003. The study was restricted to patients aged <= 75 years, of whom 18% (n = 142) were treated with chemotherapy. Only 0.9% of patients older than 75 years received chemotherapy. Results Patients who received chemotherapy were significantly younger (mean age 6 years) than those treated by surgery alone (65 years, P < 0.001), and their tumors were more often positive for vascular invasion (P=0.007). Multivariate analysis that included all prognostic factors revealed adjuvant chemotherapy was associated with improved survival (HR = 0.62, 95% CI [0.39-0.98], P = 0.043), with women gaining more benefit (HR = 0.48, 95% CI [0.20-1.22], P = 0.09) than men (HR = 0.94, 95% CI [0.54-1.64], P = 0.8). Conclusions In view of the apparent survival benefit from chemotherapy for stage II colon cancer, the present study raises concerns about the current low rates of adjuvant treatment for this disease in the community, particularly for female patients.