The black to white breast cancer incidence rate crossover.

Abstract

Abstract Abstract #2086 Background: Although breast cancer incidence rates are higher among Blacks than Whites prior to age 40 years, the reverse is true after age 40 years. This so-called Black to White ethnic crossover has been described but never systematically studied.
 Materials and Methods: To further assess the Black to White incidence rate crossover, we obtained data from the National Cancer Institute's Surveillance, Epidemiology, and End Results program. Invasive female breast cancers were stratified by Black and White race and estrogen receptor (ER) expression. Standard descriptive epidemiology was supplemented with “comparative” age-period-cohort (APC) models.
 Results:]We observed “qualitative” (reversing or crossing) age-interactions by race, stratified by birth-cohort and adjusted for calendar-period. For example, APC fitted age-at-onset curves were higher among Blacks than Whites prior to age 40 years, and then rates crossed, after which age-specific rates were higher for Whites (p ∼ 0 for difference). In contrast to age-related differences, secular trends were similar for Blacks and Whites (net drifts, p = 0.85 for difference). For all time periods and age groups, ER negative incidence rates were higher among Blacks, whereas ER positive rates were higher among Whites.
 Conclusion: When viewed as a qualitative (crossing) age-interaction, the Black to White ethnic crossover reflects the reversal of incidence rate ratios for early-onset/poor prognosis and late-onset/good prognosis breast cancer types. Blacks have more early-onset and ER-negative tumors, even after adjustment for calendar-period (screening) and birth-cohort (exposure) effects.
 
 Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 2086.