The contribution of cancer incidence, stage at diagnosis and survival to racial differences in years of life expectancy

Abstract

Background: African Americans have higher cancer mortality rates than whites. Understanding the relative contribution of cancer incidence, stage at diagnosis and survival after diagnosis to the racial gap in life expectancy has important implications for directing future health disparity interventions toward cancer prevention, screening and treatment.

Objective: We estimated the degree to which higher cancer mortality among African Americans is due to higher incidence rates, later stage at diagnosis or worse survival after diagnosis.

Design: Stochastic model of cancer incidence and survival after diagnosis.

Patients: Surveillance and Epidemiology End Result cancer registry and National Health Interview Survey data.

Measurements: Life expectancy if African Americans had the same cancer incidence, stage and survival after diagnosis as white adults.

Results: African-American men and women live 1.47 and 0.91 fewer years, respectively, than whites as the result of all cancers combined. Among men, racial differences in cancer incidence, stage at diagnosis and survival after diagnosis account for 1.12 (95% CI: 0.52 to 1.36), 0.17 (95% CI: -0.03 to 0.33) and 0.21 (95% CI: 0.05 to 0.34) years of the racial gap in life expectancy, respectively. Among women, incidence, stage and survival after diagnosis account for 0.41 (95% CI: -0.29 to 0.60), 0.26 (95% CI: -0.06 to 0.40) and 0.31 (95% CI: 0.05 to 0.40) years, respectively. Differences in stage had a smaller impact on the life expectancy gap compared with the impact of incidence. Differences in cancer survival after diagnosis had a significant impact for only two cancers-breast (0.14 years; 95% CI: 0.05 to 0.16) and prostate (0.05 years; 95% CI 0.01 to 0.09).

Conclusions: In addition to breast and colorectal cancer screening, national efforts to reduce disparities in life expectancy should also target cancer prevention, perhaps through smoking cessation, and differences in survival after diagnosis among persons with breast and prostate cancer.

Figure 1

Racial difference (white-African American) in years of life expectancy (LE) among men attributable to racial differences in cancer incidence, stage at presentation and survival after cancer diagnosis. *p < 0.05, testing the null hypothesis that the change of life expectancy difference is zero. Negative numbers indicate that higher incidence rates, fatality rates or later stage at diagnosis occurs among whites compared to African Americans and thus accounts for a decrease in the white-African American difference in life expectancy. Positive numbers indicate that higher incidence rates, fatality rates or later stage at diagnosis occurs among African Americans compared to whites and thus accounts for an increase in the white-African American difference in life expectancy.

Figure 2

Racial difference (white-African American) in years of life expectancy (LE) among women attributable to racial differences in cancer incidence, stage at presentation and survival after cancer diagnosis. *p < 0.05, testing the null hypothesis that the change of life expectancy difference is zero. Negative numbers indicate that higher incidence rates, fatality rates or later stage at diagnosis occurs among whites compared to African Americans and thus accounts for a decrease in the white-African American difference in life expectancy. Positive numbers indicate that higher incidence rates, fatality rates or later stage at diagnosis occurs among African Americans compared to whites and thus accounts for an increase in the white-African American difference in life expectancy.

Figure 3

Comparison of SEER and NHIS data on years of potential life lost (YPLL) due to specific cancers and all cancers combined. YPLL = years of potential life lost before age 75 per 1,000 persons, calculated as , where n is the number of persons at risk for death in the population. Other GI = other gastrointestinal cancers, including esophageal, pancreatic and liver.