By Caleb Hampton
A new study led by UC Davis Health has found that about half of all women will experience at least one false positive mammogram over a decade of annual screening with digital breast tomosynthesis (3D mammography). The study, which assessed the cumulative risk of receiving a false positive on a mammogram over a 10-year period, was published Friday in the medical research journal JAMA Network Open.
Breast cancer is the second leading cause of cancer-related death for women in the U.S. Regular mammography screenings help with early detection of the cancer, which lowers the risk of advanced breast cancer and death from the disease.
“A false positive result is a positive screening mammography assessment that leads to more diagnostic work-up but no diagnosis of breast cancer,” UC Davis Health said in a press release that discussed the study’s findings.
The UC Davis study, which analyzed data on 3 million screening mammograms for more than 900,000 women aged 40-79, looked at results from the standard two-dimensional (2D) mammography as well as the newer three-dimensional (3D) mammography. It found that the newer technology only slightly reduced the chance of receiving a false positive result.
The researchers at UC Davis Health estimated that over 10 years of annual 3D screening, 50 percent of women will receive at least one false positive result, 17 percent will receive a false positive short-interval follow-up recommendation, and 11 percent will receive a false positive biopsy recommendation.
In comparison, over 10 years of 2D screening, 56 percent of women will receive a false positive recall, 18 percent will receive a false positive short-interval follow-up recommendation, and 12 percent will receive a false positive biopsy recommendation.
“The screening technology did not have the largest impact on reducing false positives,” said Michael Bissell, epidemiologist in the UC Davis Department of Public Health Sciences and co-first author of the study.
Factors that had a greater impact on reducing the rate of false positives included screening every other year instead of annually and having non-dense breasts. Older women were also less likely to receive a false positive result.
According to UC Davis Health, when abnormalities are found on a mammogram, the patient is asked to do additional imaging and tests. If the patient is found to be cancer-free after the follow-up evaluation and for one year afterwards, they are considered to have received a false positive result.
“To detect breast cancer early, we need to be careful and investigate any potentially abnormal findings,” said Thao-Quyen Ho, radiologist at the University Medical Center in Ho Chi Minh, Vietnam, research fellow at UC Davis School of Medicine and co-first author on the study. “Women should not be worried if recalled for additional imaging or biopsy. The vast majority of these results are found to be benign.”
Overall, about 12 percent of 2D screening mammograms result in a patient being recalled for follow-up tests, though only about 4.4 percent of those recalls — or 0.5 percent of all mammograms — conclude with a cancer diagnosis.
While mammography plays an important role in the early detection of breast cancer, false positive results on mammograms are not harmless for patients. “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, professor and division chief of biostatistics at the UC Davis department of public health sciences and senior author of the study.
“Findings from our study highlight the importance of patient-provider discussions around personalized health,” Bissell said. “It is important to consider a patient’s preferences and risk factors when deciding on screening interval and modality.”