Breast cancer overdiagnosis common among older women
Breast cancer rates among women ages 75 to 84 years were 4.9 cases per 100 screened women compared to 2.6 cases per 100 unscreened women, according to a retrospective cohort study assessing risk of overdiagnosis.
Women screened for breast cancer after age 70 years had increased incidence of cancer that likely would not have caused symptoms in the patient's lifetime, a study found.
Researchers conducted a retrospective cohort study of 54,635 women aged 70 years and older who had been recently screened for breast cancer. They found that risk of overdiagnosis increased significantly with age. Among women ages 70 to 74 years, adjusted cumulative incidence of breast cancer was 6.1 cases (95% CI, 5.7 to 6.4) per 100 screened women versus 4.2 cases (95% CI, 3.5 to 5.0) per 100 unscreened women, leading them to calculate that an estimated 31% of breast cancer among screened women were potentially overdiagnosed.
For women ages 75 to 84 years, cumulative incidence was 4.9 cases (95% CI, 4.6 to 5.2) per 100 screened women versus 2.6 cases (95% CI, 2.2 to 3.0) per 100 unscreened women, with 47% of cases judged to be potentially overdiagnosed. For women ages 85 years and older, the cumulative incidence was 2.8 cases (95% CI, 2.3 to 3.4) per 100 among screened women versus 1.3 cases (95% CI, 0.9 to 1.9) per 100 among those not, with up to 54% overdiagnosis. Results were published Aug. 8 by Annals of Internal Medicine.
The study authors noted that they found no statistically significant reductions in breast cancer-specific death associated with screening, but they cautioned that the study was designed to estimate overdiagnosis, limiting the ability to assess all benefits and harms of screening. Overdiagnosis should be explicitly considered when making screening decisions, along with possible benefits, they wrote. The authors added that harms from overdiagnosis include the risk of complications from overtreatment, unnecessary anxiety, financial hardship, and unnecessary consumption of limited resources.
An editorial noted that improving screening technologies are causing overdiagnoses and that cancer genomics will redefine cancer by biopsy and pathology. “The 21st-century definition of cancer will recognize that breast cancer is not 1 entity but many distinct diseases with potentially different patterns of behavior calling for different treatments and, sometimes, no treatment,” it said.