Medical advances and racial/ethnic disparities in cancer survival

Abstract

Background: Although advances in early detection and treatment of cancer improve overall population survival, these advances may not benefit all population groups equally and may heighten racial/ethnic differences in survival.

Methods: We identified cancer cases in the Surveillance, Epidemiology and End Results program, who were ages > or = 20 years and diagnosed with one invasive cancer in 1995 to 1999 (n = 580,225). We used 5-year relative survival rates to measure the degree to which mortality from each cancer is amenable to medical interventions (amenability index). We used Kaplan-Meier methods and Cox proportional hazards regression to estimate survival differences between each racial/ethnic minority group relative to Whites, by the overall amenability index, and three levels of amenability (nonamenable, partly amenable, and mostly amenable cancers, corresponding to cancers with 5-year relative survival rate < 40%, 40-69%, and > or = 70%, respectively), adjusting for gender, age, disease stage, and county-level poverty concentration.

Results: As amenability increased, racial/ethnic differences in cancer survival increased for African Americans, American Indians/Native Alaskans, and Hispanics relative to Whites. For example, the hazard ratios (95% confidence intervals) for African Americans versus Whites from nonamenable, partly amenable, and mostly amenable cancers were 1.05 (1.03-1.07), 1.38 (1.34-1.41), and 1.41 (1.37-1.46), respectively. Asians/Pacific Islanders had similar or longer survival relative to Whites across amenability levels; however, several subgroups experienced increasingly poorer survival with increasing amenability.

Conclusions: Cancer survival disparities for most racial/ethnic minority populations widen as cancers become more amenable to medical interventions. Efforts in developing cancer control measures must be coupled with specific strategies for reducing the expected disparities.

Figure 1

Racial Differences in Kaplan Meier Survival Curves by Cancer Amenability Levels

Figure 2

Change in Adjusted Hazard Ratios of Cancer-specific Mortality associated with minority race by 1% increase in Amenability Note: model included age at diagnosis, stage at diagnosis, gender, county-level poverty concentration, each race/ethnicity group, 5-year relative survival rates (amenability scale) and interaction between each race/ethnicity group and 5-year-relative survival rates

Figure 3

Adjusted hazard ratios of cancer-specific mortality comparing Hispanic subgroups with White population by amenability level

Figure 4

Adjusted hazard ratios of cancer-specific mortality comparing Asian/Pacific Islander subgroups with White population by amenability level