I’ve written several articles about the difficulties inherent in screening for diseases that are common and associated with significant morbidity and mortality. The two most prominent are breast cancer and prostate cancer. Both have screening tests that are widely used, but the public and many physicians seem to be unaware of their limitations. Overdiagnosis is a big problem.
Estimating Breast Cancer Overdiagnosis After Screening Mammography Among Older Women in the United States is a paper published in the Annals of Internal Medicine in 2023. Older women (age 70 or more) commonly receive routine mammography with the efficacy of this procedure being uncertain. “The U.S. Preventive Services Task Force makes no specific recommendation for or against screening women 75 years and older, but includes women 70 to 74 years in the broader group of women for whom screening is generally recommended. The American Cancer Society recommends continuing screening if life expectancy is more than 10 years, whereas the American College of Physicians recommends discontinuing screening at age 75 years or younger if life expectancy is less than 10 years.”
The study compared the incidence of breast cancer in women over 70 who were screened compared to those who were not screened. The data below show that at each age group – 70 to 75, 74 to 84, and >85 – that the incidence of breast cancer was much higher in the screened group.
The main reason to screen for breast cancer is to reduce the mortality from the disease. Not surprisingly, the incidence of in-situ breast cancer and localized breast cancer was significantly higher in he screened group. Regional and distant breast cancer incidence was the same in the screened and unscreened groups at all ages as was breast cancer mortality.
The authors of this study take a circumspect position on their findings: “In conclusion, women 70 years and older who continue breast cancer screening are at risk for overdiagnosis. The relative risk for overdiagnosis increases with age and is highest for the oldest women or those with lowest life expectancy. Overdiagnosis should be explicitly considered when making screening decisions, along with considering possible benefits of screening.”
Screening for breast cancer in the elderly is not likely to have a great benefit. The public needs more information about the procedure if patients are to make informed decisions about whether to undergo it or forgo it. As most patients rely on their doctor for advice about the utility of mammography, it is the primary care physician who needs to study the pros and cons of mammography.
Mammography in younger women is also more complex than it seems, but that’s a discussion for another day. The full text of the paper is below.
