Abstract
PURPOSE: Adjuvant chemotherapy for stage III colon cancer produces a substantial survival benefit, but many older patients do not receive chemotherapy. This study examines factors associated with medical oncology consultation and evaluates the impact of such consultation on chemotherapy use. PATIENTS AND METHODS: We used the Surveillance Epidemiology and End Results-Medicare linked database and identified 7,569 patients, aged 66-99, with stage III colon cancer diagnosed from 1992-1999. Modified Poisson regression was used to assess the relative risk for seeing a medical oncologist and for receiving chemotherapy as a function of individual characteristics. RESULTS: 78.08% of patients saw a medical oncologist within 6 months of diagnosis. Patients who were female, white, married, had low comorbidity scores, were diagnosed in more recent years, or had four or more positive lymph nodes were more likely to see a medical oncologist. Patients seeing a medical oncologist were 10 times more likely to receive chemotherapy (odds ratio, 9.98; 95% confidence interval, 8.21-12.14), after controlling for demographic and tumor characteristics. Chemotherapy use increased over time, but was substantially lower among older, black, and unmarried patients. CONCLUSIONS: Referral to medical oncology is one of the most important factors associated with receipt of chemotherapy among older patients with stage III colon cancer. Comorbidity decreases the likelihood of receiving chemotherapy, but its effect is the same for those who see a medical oncologist and all patients combined. Ensuring that high-risk patients are referred to medical oncology is a crucial step in quality care for patients with colon cancer.