Do radiation use disparities influence survival in patients with advanced breast cancer?

The authors previously identified racial/ethnic disparities in the use of radiation therapy (RT) in patients with advanced breast cancer (BC). They hypothesized that disparities in the use of RT were associated with survival differences favoring white patients.

The authors used the Surveillance, Epidemiology, and End Results database to identify white, black, Hispanic, and Asian patients with BC associated with ≥ 10 metastatic lymph nodes diagnosed between 1988 and 2005. Multivariate analyses of overall survival (OS) and disease-specific survival (DSS) assessed age, sex, race, tumor size, histology, estrogen receptor status, progesterone receptor status, RT, and type of surgery. The authors further stratified for use of RT and type of surgery. Risk of mortality was reported as hazard ratios (HRs) with 95% confidence intervals (CIs).

Of 15,895 patients with advanced BC, 12,653 met entry criteria. On multivariate analysis, RT was associated with a decreased risk of all-cause (HR, 0.78; 95% CI 0.74-0.83; P < .001) and disease-specific (HR, 0.81; 95% CI, 0.76-0.86; P < .001) mortality; black race was associated with an increased risk of all-cause (HR, 1.54; 95% CI, 1.42-1.68; P < .001) and disease-specific (HR, 1.53; 95% CI, 1.39-1.68; P < .001) mortality. After stratifying by type of surgery and use of RT, blacks demonstrated poorer survival than their white counterparts, regardless of surgery type or receipt of RT.

Only black patients had poorer OS and DSS relative to whites. When stratified by type of surgery and use of RT, blacks continued to demonstrate poorer survival. This survival disparity is unlikely to be because of lack of RT.