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.