An overview and critical analysis of breast cancer screening.

From October 1973 through September 1979, 10,000 women were screened for breast cancer as part of a national project. In this follow-up analysis, we evaluate the current status of 166 women whose tumors were detected by this screening project (women with bilateral malignant neoplasms have been excluded). Mammogram abnormalities only were present in 55 women and abnormal physical findings with or without an abnormal mammogram were present in 111 women. Overall, 75% of patients were diagnosed with stage I (n = 86) or stage II (n = 39) disease. Median follow-up was 117 months. Only eight women (14.5%) whose tumors were detected by mammogram have suffered a relapse. Recurrences have developed in 27 women (24.3%) in the group with abnormal physical findings with or without an abnormal mammogram. Disease-free and relative survival at ten years' follow-up are 79.6% and 83.7%, respectively, for the 166 women whose cancer was detected by mammography only and by physical examination with or without an abnormal mammogram. Further follow-up will be required to determine the impact of screening detection on the natural history of breast cancer.