BREAST-CANCER AMONG BLACK-AND-WHITE WOMEN IN THE 1980S - CHANGING PATTERNS IN THE UNITED-STATES BY RACE, AGE, AND EXTENT OF DISEASE

Background. This national study of breast cancer incidence and mortali ty was conducted to determine whether patterns of change differ for bl ack and white women, to evaluate patterns by extent of disease, and to determine whether recent patterns of breast cancer are consistent wit h results that one would expect due to increases in use of screening e xaminations by women. Methods. The study included 104,351 cases of in situ or invasive breast cancer diagnosed between 1983 and 1989 among w omen from the nine geographic areas participating in the National Canc er Institute Surveillance, Epidemiology, and End Results program. Brea st cancer incidence patterns were examined by extent of disease for bl ack and white women and by age at diagnosis. Results. Significant incr eases occurred in the incidence of all early-stage breast cancers. Con comitantly, significant decreases occurred in the incidence of the mos t advanced-stage breast cancers. Although both white and black women e xperienced significant increases in early-stage breast cancer, black w omen have substantially lower rates of the least extensive breast canc ers. Conclusion. These results strongly suggest that a major explanati on for the increase in breast cancer incidence in the 1980s may well b e the increased prevalence of breast cancer screening among women in t he United States. They also suggest a consistent benefit of screening across all age groups from 40 to 49 years through 70 years and older.