Breast Cancer being Over diagnosed?
“,… About one in seven cases of screen-detected breast cancer are overdiagnosed, according to a modeling study based on data from Breast Cancer Surveillance Consortium (BCSC) centers…”
“…Of these overdiagnosed cases, 6.1% (95% UI 0.2-20.1) were due to the detection of indolent preclinical cancer, and 9.3% (95% UI 5.5-13.5) were due to the detection of progressive preclinical cancer in women who would have died from an unrelated cause before clinical diagnosis, they noted in the Annals of Internal Medicine…”
Study: Breast Cancer Is Still Being Overdiagnosed
— Though modeling study’s estimated rate of 15% is below previous estimates
by Mike Bassett, Staff Writer, MedPage Today February 28, 2022
About one in seven cases of screen-detected breast cancer are overdiagnosed, according to a modeling study based on data from Breast Cancer Surveillance Consortium (BCSC) centers.
In a program of biennial screening for women ages 50 to 74, consistent with the U.S. Preventive Services Task Force recommendation for average-risk women, 15.4% (95% uncertainty interval [UI] 9.4-26.5) of screen-detected cancer cases were estimated to be overdiagnosed, reported Marc D. Ryser, PhD, of Duke University in Durham, North Carolina, and colleagues.
Of these overdiagnosed cases, 6.1% (95% UI 0.2-20.1) were due to the detection of indolent preclinical cancer, and 9.3% (95% UI 5.5-13.5) were due to the detection of progressive preclinical cancer in women who would have died from an unrelated cause before clinical diagnosis, they noted in the Annals of Internal Medicine.
This overdiagnosis estimate is lower than previous reports of estimates as high as 30%, said Ryser in a video accompanying the study. “We have known for a long time that the most prominent estimates of breast cancer overdiagnosis in the U.S. were unrealistically high. We hope that our overdiagnosis estimate of 15% among screen-detected cancers will be adopted as a new standard and will lead to better informed decision making around breast cancer screening, follow-up testing, and treatment.”
The researchers also found that the overdiagnosis rate increased with age: from 11.5% at the first screening exam at age 50, to 23.6% at the last exam at age 74.
In addition, the relative contributions to overdiagnosis from the detection of nonprogressive and progressive types of preclinical cancer differed by screening round. The rate of overdiagnosis due to nonprogressive cancer decreased from 8.4% at the first screen to 5.5% at the last screen, while the rate due to progressive cancer that would not have become clinically evident before death increased from 3.1% to 18.1%.
“Given that approximately 7 in 1,000 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 1,000 women who undergo mammography will be found to have a cancer that would never have caused problems,” noted Felippe O. Marcondes, MD, and Katrina Armstrong, MD, both of Massachusetts General Hospital in Boston, in an accompanying editorial.
If 60% of the 280,000 cases of breast cancer diagnosed each year in the U.S. are found through screening, eliminating overdiagnoses would spare 25,000 women the cost and inconvenience of unnecessary treatment, they said. This would require “substantial advances” in major areas, including:
- Developing better predictive ability with the goal of accurately identifying tumors that will not progress
- Improving the accuracy of screening technologies to both reduce the risk for overdiagnosis and improve the ability to detect breast cancer missed by mammography
- Implementing prevention strategies to reduce the rate of breast cancer diagnosis overall, such as providing counseling about lifestyle modifications, as well as screening for genetic risk
Estimates for this study were based on individual screening and diagnosis histories among a cohort of 35,986 women who underwent one or more screening mammograms at a BCSC facility from 2000 through 2018. Of the included women, 64.4% were white, 19% were Asian, 12.1% were Black, and 11% were Hispanic. Median age at first screening exam was 56.
A total of 82,677 mammograms were conducted, and there were 718 breast cancer diagnoses. Most cases of cancer (90%) were screen detected, and most were diagnosed during the first screening round.