Trends in distant-stage breast, colorectal, and prostate cancer incidence rates from 1992 to 2004: potential influences of screening and hormonal factors.

Differential utilization of cancer screening between populations could lead to changes in cancer disparities. Evaluating incidence rates trends is one means of monitoring these disparities. Using Surveillance, Epidemiology, and End Results data, we compared annual percent changes (APC) in age-adjusted incidence rates of distant-stage breast, colorectal, and prostate cancer between non-Hispanic whites (NHW) and African Americans (AA). From 1992 to 2004, distant-stage breast cancer incidence rates remained essentially constant among both AA and NHW women, though rates were 30-90% higher among AA women throughout. NHW men and women experienced declines in distant-stage colorectal cancer incidence rates [APC = -1.6, 95% confidence interval (CI) -2.3, -0.9], but AA men and women did not. Distant-stage prostate cancer incidence rates declined for both AA (APC = -5.8, 95% CI -7.9, -3.8) and NHW (APC = -5.1, 95% CI -6.7, -3.4). Despite now having nearly equal mammography screening rates, the persistent breast cancer disparity observed among AAs compared to NHWs may be due to the greater susceptibility of AAs to more aggressive tumors, particularly hormone-receptor-negative disease, which is more difficult to detect by mammography. For colorectal cancer, greater utilization of screening tests among NHWs vs. AAs is likely a primary contributor to the observed widening disparity. Wider recognition of AA race as a prostate cancer risk factor may contribute to the narrowing disparity in the incidence of disease.