Racial and Ethnic Disparities in Cancer Survival: The Contribution of Tumor, Sociodemographic, Institutional, and Neighborhood Characteristics

Abstract

Purpose Racial/ethnic disparities in cancer survival in the United States are well documented, but the underlying causes are not well understood. We quantified the contribution of tumor, treatment, hospital, sociodemographic, and neighborhood factors to racial/ethnic survival disparities in California. Materials and Methods California Cancer Registry data were used to estimate population-based cancer-specific survival for patients diagnosed with breast, prostate, colorectal, or lung cancer between 2000 and 2013 for each racial/ethnic group (non-Hispanic black, Hispanic, Asian American and Pacific Islander, and separately each for Chinese, Japanese, and Filipino) compared with non-Hispanic whites. The percentage contribution of factors to overall racial/ethnic survival disparities was estimated from a sequence of multivariable Cox proportional hazards models. Results In baseline models, black patients had the lowest survival for all cancer sites, and Asian American and Pacific Islander patients had the highest, compared with whites. Mediation analyses suggested that stage at diagnosis had the greatest influence on overall racial/ethnic survival disparities accounting for 24% of disparities in breast cancer, 24% in prostate cancer, and 16% to 30% in colorectal cancer. Neighborhood socioeconomic status was an important factor in all cancers, but only for black and Hispanic patients. The influence of marital status on racial/ethnic disparities was stronger in men than in women. Adjustment for all covariables explained approximately half of the overall survival disparities in breast, prostate, and colorectal cancer, but it explained only 15% to 40% of disparities in lung cancer. Conclusion Overall reductions in racial/ethnic survival disparities were driven largely by reductions for black compared with white patients. Stage at diagnosis had the largest effect on racial/ethnic survival disparities, but earlier detection would not entirely eliminate them. The influences of neighborhood socioeconomic status and marital status suggest that social determinants, support mechanisms, and access to health care are important contributing factors.

Fig 1.

Change in hazard ratios (HRs) with addition of covariables into multivariable models for each racial/ethnic group, by cancer site and sex: (A) breast cancer, (B) prostate cancer, (C) men with lung cancer, (D) woman with lung cancer, (E) men with colorectal cancer, and (F) women with colorectal cancer. Solid gray line, non-Hispanic white (reference); blue line with 95% CIs, non-Hispanic black; yellow line with 95% CIs, Hispanic; dark blue line with 95% CIs, Asian American and Pacific Islander; light red dashed line, Chinese; light gray dotted line, Japanese; red long-dashed line, Filipino. Comp, composition; Hosp insure, hospital insurance composition; Hosp R/E, hospital racial/ethnic composition; Hosp SES, hospital SES composition; HR, hormone receptor; NCI, National Cancer Institute cancer center; nR/E, neighborhood racial/ethnic composition; nSES, neighborhood socioeconomic status.