Breast Ca Mortality Declines by 63%.

DANA POINT, CALIF. -- Regular mammographic screening contributed to a 63% decline in breast cancer mortality in a study of breast cancer deaths that occurred in two Swedish counties over a 29-year period.

Approximately 70% of the observed reduction in breast cancer deaths can be attributed to early cancer detection, with the remainder due to improvements in therapy for breast cancer and greater awareness of the disease, Robert Smith, Ph.D., said at a science writers seminar sponsored by the American Cancer Society.

Even after taking these other factors into consideration and adjusting for possible selection bias, screening led to a nearly 50% reduction in breast cancer mortality, which is significantly higher than the 30% estimate that had been reported in previous randomized, controlled trials.

The study, which was based on data from 1968 to 1996, included all women aged 20-69-years who lived in the two counties. During the entire period, 6,807 women were diagnosed with breast cancer, and 1,863 died of the disease (Cancer 91(9):1724-31, 2001).

Dr. Smith, who is director of cancer screening for the ACS, Atlanta, and his associates examined deaths from breast cancer during three time periods: 1968-1977, before mammography had been introduced; 1978-1987, when some women aged 40-74 received ...