Since 1975, the rate of deaths from breast cancer has declined substantially, from 48 deaths per 100,000 women in 1975 to 38 per 100,000 in 2000. During this time, the use of screening mammography has become widespread, with about 70% of women over age 40 reporting a mammogram within the previous two years in 2000. Also, more women with breast cancer are being treated with adjuvant therapy (chemotherapy and medications in addition to surgery). To what extent has screening and adjuvant therapy contributed to the decline in breast cancer deaths?

A new study in the October 27, 2005 issue of the New England Journal of Medicine examined the breast cancer death rate in the US and found that screening and adjuvant therapy contributed similarly to the reduction in breast cancer deaths.

About the Study

The National Institutes of Health identified seven institutions to help conduct this study: the Dana Farber Cancer Institute, Erasmus University Medical Center, Georgetown University, the MD Anderson Cancer Center, Stanford University, the University of Rochester, and the University of Wisconsin—Madison. Researchers at each institution developed models to estimate the effect of screening and treatment on the breast cancer death rate in the US from 1975 to 2000. The researchers used data on the incidence of breast cancer, breast cancer death rate, and uses and effectiveness of breast cancer screening and treatment from large, nationally representative databases.

The researchers estimated that 28% to 65% of the decline in breast cancer death rate from 1975 to 2000 could be attributed to screening, and the rest attributed to adjuvant therapy. Overall, the contributions of screening and adjuvant therapy were similar.

It is important to note that this study is limited because each institution developed a unique model, based on different data and various approaches. While the overall picture was relatively consistent, the institutions’ estimates showed considerable variation.

How Does This Affect You?

These findings suggest that the advances in breast cancer screening and treatment over past 30 years are life-saving. The study also highlights the importance of the combination of screening and treatment. Without treatment, screening would not be beneficial, and without screening, treatment would not be as effective.

If you are a woman older than 40 (earlier if you have a family history of breast cancer), talk to your doctor about scheduling regular screening mammography. In most cases, the earlier breast cancer is detected, the more likely treatment will be effective. And if you or someone you know is diagnosed with early breast cancer, you can be comforted by these results: modern treatments apparently do save lives.