The impact of socioeconomic status and race on trial participation for older women with breast cancer

BACKGROUND. Older women, and older minorities in particular, are under represented in breast cancer trials. Although socioeconomic status (SES) is associated with both race and age, to the authors' knowledge little is known regarding the impact of SES on trial enrollment among older women with breast cancer. METHODS. The authors performed a case-control study comparing women who were participants in National Cancer Institute cooperative group breast cancer trials (cases) with a population-based sample of breast cancer patients (controls) obtained from the linked Surveillance, Epidemiology, and End Results (SEER)Medicare data base. The sample was restricted to women age greater than or equal to 65 years who were living in SEER areas. Proxies for SES included the proportion of the population below poverty level (by zip code) and unemployed (by county) as well those with Medicaid insurance coverage. A multivariable logistic regression model was used to test the association of SES with trial participation after accounting for other patient and county characteristics. RESULTS. In bivariate analysis, trial participants were significantly less likely than community cancer patients to reside in high-poverty zip codes (20.9% vs. 24.9%, respectively; P < 0.001) or to have Medicaid insurance (2.0% vs. 10.0%0; P < 0.0001). After adjusting for race, age, and county, trial participation remained inversely related to residing in areas with high poverty (odds ratio [OR] vs. residents of remaining counties, 0.78; 95% confidence interval [95% CI], 0.62-0.98), high unemployment rates (OR vs. residents of residents of counties in the lowest quartile, 0.50; 95% CI, 0.35-0.71), and having Medicaid insurance (OR vs. women without Medicaid, 0.22; 95% CI, 0.13-0.37); black race was not found to be related to trial participation (OR for black vs. white, 1.0; 95% CI, 0.67-1.47). CONCLUSIONS. Low SES was associated inversely with trial enrollment for older women with breast cancer and appeared to account for the enrollment disparities between black patients and white patients. Future efforts to enhance enrollment of elderly women in cancer research should specific barriers related to SES that may be amenable to intervention. (C) 2004 American Cancer Society.