Clinical Question

What is the likelihood of the overdiagnosis of breast cancer after screening in women older than 70 years?

Bottom Line

Overdiagnosis of breast cancer—or identification, in this case—that would not have caused symptoms in a person's lifetime seems to increase with age. In this study, the overdiagnosis rate was 31% for women 70 to 74 years of age. The rate of overdiagnosis increased with age: 47% for women 75 to 84 years of age and 51% for women older than 85 years who were screened and found to be positive. (Level of Evidence = 2b)

Synopsis

The investigators used a U.S. payment database to identify all women older than 70 years who had had a recent screening mammogram and followed them for up to 15 years. The authors used a two-step approach: (1) identifying women without breast cancer who had a negative screening result after 70 years of age, and (2) following these women to see if they had another mammogram in the next three years and a subsequent diagnosis of breast cancer. In this group of 54,635 women, there was no reduction in breast cancer–related death associated with screening. Women 70 to 74 years of age had a cumulative incidence of breast cancer of 6.1 per 100 women screened compared with 4.2 cases per 100 women who were not screened. This resulted in an estimated 31% of breast cancer being overdiagnosed. In women 75 to 84 years of age, the incidence was 4.9 vs. 2.6 per 100 women, with the rate of overdiagnosis being 47%. More than one-half (51%) of women 85 years and older with a diagnosis of breast cancer died of other causes.