Breast Cancer Incidence and Mortality in the Breast Cancer Detection Demonstration Project

The Breast Cancer Detection Demonstration Project (BCDDP) was a program of five annual screening examinations for breast cancer that was conducted at 29 centers in the United States. This report presents data on breast cancer incidence and mortality among the participants. A total of 283,222 women were enrolled. Our analysis is based on 55,053 white women who were 35-74 years of age at entry and who were selected for follow-up. For the first 9 years after entry, the cumulative incidence of breast cancer was estimated as 243.6 per 10,000, which is 1.34 times the expected incidence derived by use of data from the Surveillance, Epidemiology, and End Results (SEER) program. In contrast, 9-year cumulative mortality from breast cancer was only 79.6% of that expected in women with the age distribution of BCDDP participants who did not have diagnosed breast cancer at the start of observation. The ratio of observed to expected breast cancer mortality was 0.89 for women 35-49 years of age at entry, 0.76 for women 50-59 years of age at entry, and 0.74 for women 60-74 years of age at entry. Breast cancer incidence and mortality were lower for women who entered the BCDDP for routine screening than they were for women who entered for a reason such as concern about breast disease, family history of breast cancer, or a physician's recommendation. Among cases diagnosed within 5 years of entry, the 5-year case fatality attributed to breast cancer was 8.5%. Case fatality for all stages combined was greater than 50% lower for cases that were screen-detected than it was for cases that were not screen-detected. Case fatality was lower for cases diagnosed within the first 5 years of entry (which encompassed the period of screening) than it was for cases diagnosed in the sixth or seventh years.