Explaining Black–White Differences in Receipt of Recommended Colon Cancer Treatment

Abstract

Background: Black–white disparities exist in receipt of recommended medical care, including colorectal cancer treatment. This retrospective cohort study examines the degree to which health systems (e.g., physician, hospital) factors explain black–white disparities in colon cancer care. Methods: Data from the Surveillance, Epidemiology, and End Results program; Medicare claims; the American Medical Association Masterfile; and hospital surveys were linked to examine chemotherapy receipt after stage III colon cancer resection among 5294 elderly (≥66 years of age) black and white Medicare-insured patients. Logistic regression analysis was used to identify factors associated with black–white differences in chemotherapy use. All statistical tests were two-sided. Results: Black and white patients were equally likely to consult with a medical oncologist, but among patients who had such a consultation, black patients were less likely than white patients (59.3% versus 70.4%, difference = 10.9%, 95% confidence interval [CI] = 5.1% to 16.4%, P <.001) to receive chemotherapy. This black–white disparity was highest among patients aged 66–70 years (black patients 65.7%, white patients 86.3%, difference = 20.6%, 95% CI = 10.7% to 30.4%, P <.001) and decreased with age. The disparity among patients aged 66–70 years also remained statistically significant in the regression analysis. Overall, patient, physician, hospital, and environmental factors accounted for approximately 50% of the disparity in chemotherapy receipt among patients aged 66–70 years; surgical length of stay and neighborhood socioeconomic status accounted for approximately 27% of the disparity in this age group, and health systems factors accounted for 12%. Conclusions: Black and white Medicare-insured colon cancer patients have an equal opportunity to learn about adjuvant chemotherapy from a medical oncologist but do not receive chemotherapy equally. Little disparity was explained by health systems; more was explained by illness severity, social support, and environment. Further qualitative research is needed to understand the factors that influence the lower receipt of chemotherapy by black patients.