Racial Differences in Colorectal Cancer Incidence and Mortality in the Women's Health Initiative
A partir de la cohorte « Women's Health Initiative », cette étude américaine évalue les disparités ethniques dans l’incidence du cancer colorectal et la mortalité
Background: Colorectal cancer (CRC) incidence and mortality rates are higher in African Americans as compared to other racial/ethnic groups. The Women's Health Initiative (WHI) study sample was used to determine whether differences in CRC risk factors explain racial/ethnic differences in incidence and mortality. Methods: The WHI is a longitudinal study of postmenopausal women recruited from 40 centers. Baseline questionnaires were used to collect socio-demographic and health status information. All CRC diagnoses were centrally adjudicated. Cox regression models were used to compute hazard ratios (HRs) and 95% confidence intervals (CIs) for invasive CRC by race/ethnicity. Results: The study sample included 131,481 (83.7%) White, 14,323 (9.1%) African American, 6,362 (4.1%) Hispanic, 694 (0.4%) Native American and 4,148 (2.6%) Asian/Pacific Islanders. After a mean follow-up of 10.8 years (SD 2.9), CRC incidence was highest in African Americans (annualized rate = 0.14%), followed by Whites and Native Americans (0.12% each), Asian/Pacific Islanders (0.10%) and Hispanics (0.08%). After adjustment for age and trial assignment, Hispanics had a lower risk compared to Whites, HR 0.73 (95% CI: 0.54-0.97) (p=0.03), and African Americans had a marginally greater risk, HR 1.16 (95% CI: 0.99-1.34), p=0.06. Multivariable adjustment attenuated the difference in incidence between African Americans and Whites (HR 0.99, 95% CI: 0.82-1.20), while strengthening the lower HR for Hispanics (HR 0.68, 95% CI: 0.48-0.97). Conclusions: African American/White differences in CRC risk are likely due to sociodemographic/cultural factors other than race. Impact: A number of modifiable exposures could be a focus for reducing CRC risk in African Americans.