Background: Disparities in cancer survival may be related to differences in stage. Segregation may be associated with disparities in stage, particularly for cancers for which screening promotes survival.
Objectives: The objective of the study was to examine whether segregation modifies racial/ethnic disparities in stage.
Design: The design of the study was analysis of Surveillance, Epidemiology, and End Results Medicare data for seniors with breast, colorectal, lung, and prostate cancer (n = 410,870).
Measurements and main results: The outcome was early- versus late-stage diagnosis. Area of residence was categorized into 4 groups: low segregation/high income (potentially the most advantaged), high segregation/high income, low segregation/low income, and high segregation/low income (possibly the most disadvantaged). Blacks were less likely than whites to be diagnosed with early-stage breast, colorectal, or prostate cancer, regardless of area. For colorectal cancer, the black/white disparity was largest in low-segregation/low-income areas (black/white odds ratio [OR] of early stage 0.51) and smallest in the most segregated areas (ORs 0.71 and 0.74, P < .005). Differences in disparities in stage by area category were not apparent for breast, prostate, or lung cancer. Whereas there were few Hispanic-white differences in early-stage diagnosis, the Hispanic/white disparity in early-stage diagnosis of breast cancer was largest in low-segregation/low-income areas (Hispanic/white OR of early stage 0.54) and smallest in high-segregation/low-income areas (OR 0.96, P < .05 compared to low-segregation/low-income areas).
Conclusions: Disparities in stages for cancers with an established screening test were smaller in more segregated areas.