Study Finds Risk of Breast Cancer Overdiagnosis Among Older Women After Screening

In a retrospective cohort study, a team of researchers found that women aged 70 years and older may be overdiagnosed with breast cancer after screening for the disease.

Overdiagnosis—a diagnosis that would not have caused any harm or death to the patient—is “increasingly recognized as a harm of breast cancer screening,” according to the study authors.

A total of 54,635 women were included in the study that compared the cumulative incidence of breast cancer among women who continued their cancer screening in the next interval to those who did not. The data was collected from fee-to-service Medicare claims that were linked to the Surveillance, Epidemiology, and End Results program. The researchers used the breast cancer diagnosis and breast cancer death for up to 15 years follow-up as their measurement for the study.

The adjusted cumulative incidence of breast cancer for women aged 70 to 74 years was 6.1 cases per 100 screened compared with 4.2 cases per 100 unscreened women. In total, an estimated 31% of cases of breast cancer among screened women aged 70 to 74 years were potentially overdiagnosed. For women aged 75 to 84 years and women aged 85 and older, the cumulative incidence of breast cancer cases in those screened was slightly lower: 4.9 per 100 women vs 2.6 unscreened and 2.8 per 100 women vs 1.3 unscreened, respectively. Women in the 75 to 84 years age group had 47% of cases potentially overdiagnosed, and women aged 84 years had 54% of overdiagnosed cases.

The study had limitations. For example, the authors noted that their study focused on overdiagnosis only, which limited their ability to draw conclusions on the broader benefits and harms of breast cancer screening.

“Continued breast cancer screening was associated with greater incidence of breast cancer, suggesting overdiagnosis may be common among older women who are diagnosed with breast cancer after screening. Whether harms of overdiagnosis are balanced by benefits and for whom remains an important question,” the researchers concluded.

Reference:

Richman IB, Long, JB, Soulos PR, W SY, Gross CP. Estimating breast cancer overdiagnosis after screening mammography among older women in the United States. Ann Intern Med. 2023;176(9):1172-1180. doi:10.7326/M23-0133