Half of all women who receive mammograms annually for more than 10 years will have false-positive results, new findings suggest. Although digital breast tomosynthesis (DBT or 3D mammography) was associated with fewer recalls for false-positive results over a 10-year study period compared with standard mammography, the differences were modest (49.6% vs 56.3%, respectively), according to the results of a study in JAMA Network Open.1

The risk for false-positive results was considerably lower in women screened every other year. Other factors linked to a lower false-positive risk included older age and having non-dense breasts.

“The screening technology did not have the largest impact on reducing false positives,” said Michael Bissell, PhD, epidemiologist in the UC Davis Department of Public Health Sciences and co-first author of the study.2 “Findings from our study highlight the importance of patient-provider discussions around personalized health. It is important to consider a patient’s preferences and risk factors when deciding on screening interval and modality.”


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The current study “may be the first study to calculate cumulative false-positive results with DBT over a relatively long period of screening, providing important information to guide contemporary shared decision-making about whether to initiate mammography and how frequently to screen,” wrote Lydia E. Pace, MD, MPM, in an accompanying commentary.3

False-Positive Mammograms Are Common

Breast cancer is the second leading cause of cancer-related death among women in the US; each year approximately 255,000 cases are diagnosed in women. Early detection using screening mammography is a key strategy to lower the risk for advanced breast cancer and death from this disease. Use of 3D mammography “has been associated with increased cancer detection and decreased recall rates, leading to optimism that DBT screening could lead to a more favorable ratio of benefits,” Dr Pace said.

“Despite the important benefit of screening mammography in reducing breast cancer mortality, it can lead to extra imaging and biopsy procedures, financial and opportunity costs, and patient anxiety,” said Diana Miglioretti, PhD, professor and division chief of biostatistics at the UC Davis Department of Public Health Sciences, UC Davis Comprehensive Cancer Center researcher and senior author of the study.

False-positive results are common. Although approximately 12% of 2D screening mammograms are recalled for more workup, only 4.4% of those recalls, or 0.5% overall, conclude with a cancer diagnosis.

“To detect breast cancer early, we need to be careful and investigate any potentially abnormal findings. So, women should not be worried if recalled for additional imaging or biopsy. The vast majority of these results are found to be benign,” said Thao-Quyen Ho, MD, PhD, radiologist at the University Medical Center in Ho Chi Minh, Vietnam, research fellow at UC Davis School of Medicine and co-first author of the study.

What the Study Found

The researchers analyzed data collected by the Breast Cancer Surveillance Consortium on 3 million screening mammograms for 903,495 women aged 40 to 79 years. The screenings were performed between 2005 and 2018 at 126 radiology facilities. 

The study authors evaluated screening modality, screening interval, age, and breast density. It estimated the cumulative risk that a woman would receive at least 1 false-positive recall over 10 years of annual or biennial (every other year) screening. It also assessed the risks of a false-positive that resulted in a recommendation to repeat imaging within 6 months (short interval follow-up) and, separately, in a biopsy recommendation.

The probability of receiving at least 1 false-positive recall over a 10-year period was slightly lower with 3D than 2D digital mammography. The researchers estimated that over 10 years of annual DBT screening, 49.5% of women will experience at least 1 false-positive recall, 17% a false-positive short-interval follow-up recommendation, and 11% a false-positive biopsy recommendation. This is compared with 56.3% of women screened with 2D digital mammograms having a false-positive recall, 18% a short-interval follow-up recommendation, and 12% a biopsy recommendation.

Regardless of the type of screening, the rate of false-positive results were substantially lower for older than younger age groups and women with entirely fatty versus extremely dense breasts.

Women screened every other year had a considerably lower probability of at least 1 false-positive result than women who received annual mammograms over 10 years of screening. This finding was observed for both 3D and 2D mammography (35.7% and 38.1%, respectively).

“We were surprised that the newer 3D technology in breast cancer screening does not substantially reduce the risk of having a false-positive result after 10 years of screening; however, chances of false positives are much lower with repeated biennial vs annual screening,” said Dr Ho.

For short-interval follow-up recommendations, 17% of women undergoing annual 3D mammography are estimated to have at least 1 false-positive result over 10 years, compared to just 10% of those undergoing biennial screening. False-positive benign biopsy recommendations are estimated to occur in 11% of women receiving annual 3D mammograms but in only 7% of those screened every 2 years.

“Although many women tolerate false-positive results, they are associated with at least transient anxiety as well as time, inconvenience, and expense,” wrote Dr Pace. “More information is needed to understand the association of DBT with overdiagnosis, which is the more clinically important harm of screening, although with the greater cancer detection rate of DBT, it seems quite likely that DBT is associated with more overdiagnosis.”

References

1. Ho TQH, Bissell MCS, Kerlikowske, K, et al. Cumulative probability of false-positive results after 10 years of screening with digital breast tomosynthesis vs digital mammography. JAMA Netw Open. 2022;5(3):e222440. doi:10.1001/jamanetworkopen.2022.2440

2. UC Davis Health. Half of all women experience false positive mammograms after 10 years of annual screening. News release. March 25, 2022. Accessed April 4, 2022. https://health.ucdavis.edu/news/headlines/half-of-all-women-experience-false-positive-mammograms-after-10-years-of-annual-screening-/2022/03

3. Pace LE. False-positive results of mammography screening in the era of digital breast tomorsynthesis. JAMA Netw Open. 2022;5(3):e222445. doi:10.1001/jamanetworkopen.2022.2445