Recent trends in the incidence of in situ and invasive breast cancer in the Detroit metropolitan area (1975-1988).

Abstract

Over the past two decades, breast cancer incidence rates have increased dramatically for women in all age groups. Breast cancer incidence trends were evaluated in a population-based study of data from the Metropolitan Detroit Cancer Surveillance System, a participant in the Surveillance Epidemiology and End Results Program of the National Cancer Institute. Incidence rates from 1975 through 1988 were evaluated, based on tumor size, age at diagnosis, and race. Age-adjusted rates for all breast cancers have increased since 1975, with the largest change occurring since 1983. Age-adjusted incidence rates for ductal carcinoma in situ (DCIS) and cancers smaller than 2.0 cm were higher in white women than black women, whereas age-adjusted incidence rates for larger tumors (> or = 2.0 cm) have been higher in black women since 1985. The rate of increase in incidence as measured by the average interval percentage change was highest for DCIS and small invasive tumors (< 1.0 cm) for all age groups of women. The more rapid increase in incidence of early breast cancer in the population suggests that the observed increase in breast cancer incidence over the last 2 decades may have resulted, at least in part, from a screening effect.