Screening Mammography and Supplementary Treatment Leads to a Reduction in Breast Cancer Mortality from 1975 – 2000
In 1975, 48.3 per 100,000 women between the ages of 30 and 79 died from breast cancer (adjusted to the 2000 population). In 2000, the number of deaths due to breast cancer dropped to 38.0 per 100,000 women. This decrease can be attributed to screening mammography and adjuvant therapy, according to a recent article in the New England Journal of Medicine.1
The National Institutes of Health selected seven teams of investigators to create different statistical models of breast cancer incidence and mortality. Each group used the same sources to obtain data on mammography screening, subsequent treatment, and benefits of the treatment in terms of death rate due to breast cancer, but their approaches and assumptions were different.
Between 1975 and 2000, mammography became much more common. Figure 1 shows the percentage of women over age 40 who had a mammogram at time periods between 1985 and 2000. Screening mammography increased significantly during this time period.
Each group found that screening and treatment have contributed to the decline in death rate from breast cancer and that this decline is attributed to a combination of both screening and treatment — not to either on alone, according to the study authors.
1. Berry, D.A. et al. "Effect of Screening and Adjuvant Therapy on Mortality from Breast Cancer," The New England Journal of Medicine, October 27, 2005, 1784 - 92.
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