A new study suggests that 1 in 7 cases of screen-detected breast cancer may be overdiagnosed, and a related editorial outlines ways to reduce the burden of overdiagnosis. Both articles were published in the Annals of Internal Medicine.1,2
For the study, researchers analyzed a cohort of women who had their first mammography screen between 2000 and 2018. The study ultimately included 35,986 women, 82,677 mammograms, and 718 breast cancer diagnoses.
In a program of biennial screening from age 50 to 74 years, 15.4% of screen-detected breast cancer cases were estimated to be overdiagnosed. Of these cases, 6.1% were indolent preclinical cancer, and 9.3% were cases of progressive preclinical cancer in women who would have died of an unrelated cause before clinical diagnosis.
“Given that approximately 7 in 1000 women will be diagnosed with invasive or noninvasive breast cancer on the basis of a screening mammogram, women should be told that approximately 1 in 1000 women who undergo mammography will be found to have a cancer that would never have caused problems,” the editorialists wrote.
“Assuming that about 60% of the 280,000 cases of breast cancer diagnosed in the United States each year are found through mammography screening, eliminating overdiagnosis could spare 25,000 women the cost and complications of unnecessary treatment,” they added.
Three Areas of Need
According to the editorialists, reducing the burden of overdiagnosis will require advances in 3 areas. The first need is for better information about which tumors will progress.
“More recent advances in genomics, proteomics, and cancer immunology (including single cell techniques) offer the promise of improving predictive ability with the goal of accurately identifying tumors that will not progress,” the editorialists wrote. “[P]rediction models will need to be quite accurate to influence treatment decisions.”
The second area of need is improved accuracy of screening technologies, which could reduce the risk of overdiagnosis as well as missed diagnoses.
“Recent innovations in imaging technology, methods for interpretation (including artificial intelligence), and individualized screening approaches offer important opportunities to reduce overdiagnosis and screening failure and should be pursued,” the editorialists wrote.
The third area of need is primary prevention strategies that can reduce breast cancer diagnoses overall. This includes counseling about lifestyle modification that might reduce the risk of breast cancer and screening for genetic risk, followed by offers of chemoprevention and prophylactic surgery for high-risk patients.
“Screening tests, whether for cancer or other conditions, can provide great benefit by detecting disease when it is more easily treatable,” the editorialists wrote. “However, the risk of labeling millions of persons as having a disease without improving their outcomes is very real. For now, the key to navigating these tradeoffs remains open and effective physician-patient communication, rigorous evaluation of all proposed screening strategies, and continued investment in early detection research.”
Disclosures: The editorialists reported having no conflicts of interest. Some of the study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original references for a full list of disclosures.
- Ryser MD, Lange J, Inoue LYT, et al. Estimation of breast cancer overdiagnosis in a U.S. breast screening cohort. Ann Intern Med. Published online March 1, 2022. https://doi.org/10.7326/M21-3577
- Marcondes FO, Armstrong A. Reducing the burden of overdiagnosis in breast cancer screening and beyond. Ann Intern Med. Published online March 1, 2022. https://doi.org/10.7326/M22-0483