A major, new study led by UC Davis Comprehensive Cancer Center researcher Diana Miglioretti found women who receive a false-positive mammography result that requires additional imaging or biopsy were less likely to return for future routine screening.
Early detection of breast cancer through mammography continues to save lives. However, abnormal findings on mammograms can lead to additional imaging and biopsies, many of which turn out to be “false positives,” meaning there is no cancer diagnosis. False positives can also have financial implications for patients and cause significant emotional anxiety.
“The finding raises concerns about the potential unintended consequence of false-positive results, where women may avoid screening mammograms in the future,” said Miglioretti, lead author of the study and chief of the Division of Biostatistics at UC Davis.
The research was published in the Annals of Internal Medicine. It analyzed data for more than 3.5 million screening mammograms nationwide performed between 2005 and 2017. The results included over 1 million patients aged 40 to 73.
Findings are worrisome to researchers
The study found that 77% of women with a negative result from a mammogram returned for subsequent screening. But this percentage dropped to 61% after a false-positive finding requiring another mammogram in six months to confirm the results. It decreased to 67% if a biopsy was recommended. The impact was even more pronounced for women who received false-positive results on two consecutive mammograms — only 56% returned for recommended screenings.
The high rate of women who don’t return for future screening is concerning to the research team.
“It is important for women with false-positive results to continue screening every one to two years,” Miglioretti said, “Having a false-positive result, especially if it results in a diagnosis of benign breast disease, is associated with an increased risk of being diagnosed with breast cancer in the future.”
The research also showed that Asian and Latina women were the least likely to return for future screening mammograms after a false-positive result, which may contribute to existing health disparities.
False-positive results are common, especially among younger women. They occur in 10–12% of mammograms in women 40–49 years of age. After 10 years of annual screenings, 50–60% of women can expect at least one false-positive and 7–12% at least one false-positive with a biopsy recommendation.
“It’s important to understand that most women recalled for additional imaging due to a finding on a screening mammogram do not have breast cancer,” Miglioretti said. “They should try not to be worried if they are recalled for additional work-up. It is a normal and common part of the screening process.”
About 10% of the time, additional imaging is necessary to get a better look at an area that appeared questionable on a screening mammogram.
Why do false-positive results occur?
False-positive results occur when an abnormality appears on a mammogram, but further testing reveals there is no cancer. They can happen for a variety of reasons, including:
- Breast tissue density: Women with dense breast tissue have more fibrous and glandular tissue, which can increase the difficulty of distinguishing between normal and abnormal areas. Younger women are more likely to have dense breast tissue, which is the main reason why they have a higher incidence of false positives.
- Calcifications: Small calcium deposits in the breast, known as calcifications, can sometimes be mistaken for cancer on a mammogram, particularly if they appear in clusters or have certain patterns.
- Overlapping tissue: Overlapping breast tissue can create shadows or areas that look like masses or abnormalities on a mammogram. A newer-technology, 3D mammogram reduces the chance of this happening.
- Normal variations in breast tissue: Sometimes normal variations in breast tissue resemble cancerous growths but are not.
