3D breast imaging may detect aggressive cancers earlier in certain groups of women. Photo by uschenkova/Shutterstock
A 3D imaging technique for breast cancer screening may not offer advantages over standard digital mammography for many women, but may significantly reduce the likelihood of an advanced cancer diagnosis and avert deaths for those at higher-than-average risk and with the densest breasts, a new study says.
The federally funded study, published Tuesday in the Journal of the American Medical Association, focused on digital breast tomosynthesis, a technique approved for marketing by the Food and Drug Administration in 2011 and now widely available.
Publication of the study follows a June 8 report by the American Academy of Radiology that found the use of breast imaging services, including mammography screening, is at 85.3% of the pre-COVID-19 pandemic level.
That raised concerns that screening mammography will remain under-utilized among asymptomatic women.
Of the 504,427 women ages 40 to 79 who participated in the new study, a small percentage — 3.6% — “clearly benefit from DBT with respect to reducing the rate of advanced breast cancer diagnosis,” said Dr. Karla Kerlikowske, a professor of medicine, epidemiology and biostatistics at the University of California-San Francisco and the study’s lead author.
Unlike a standard digital mammogram, which uses low-dose X-rays to produce front and side images of the breast, tomosynthesis X-rays the breast from many angles to create 3D images.
The 3D breast imaging technique was “developed with the expectation it would improve detection of breast cancer in women with dense breasts and decrease false-positive results,” Kerlikowske said in a news release.
“Our study shows that overall, DBT does not reduce the risk of tumors becoming symptomatic between screening intervals or being missed by screening.”
“But the fact that our study shows a decrease in advanced cancer diagnosis among women with the highest density and higher-than-average risk of breast cancer and an increase in early-stage cancer detection for women with higher-than-average risk of breast cancer suggests that DBT may allow detection of aggressive cancers earlier, before they become advanced in specific groups of women,” she said.
Kerlikowske was joined in the study by nearly a dozen researchers across the United States, who used data from the Breast Cancer Surveillance Consortium to compare screening outcomes for participants at 44 consortium facilities from 2011 through 2018.
Women were grouped into cancer risk categories using the consortium’s risk-assessment tool and breast density measurements made during screening.
For most of the study population, the researchers did not find a statistically significant difference in the rates of diagnosis of advanced cancer or, for the entire study population, in the rates of cancers diagnosed between screening intervals or missed on mammography.
But researchers found the 3D imaging technique provided additional benefits for women with other specific risk profiles. For example:
The 3D screening technique resulted in fewer false-positive results and in turn fewer breast biopsies in which no cancer was detected among the nearly 44% of women participating in the study who had non-dense breasts and low-to-average risk for breast cancer.
Also, the 3D breast imaging had a higher rate of detection of small invasive breast cancers that were contained within the breast among the 29% of women in the study with “scattered fibroglandular densities or heterogeneously dense breasts and also a higher-than-average breast cancer risk,” researchers said, explaining this suggests the technique was identifying more breast cancers earlier than digital mammography.
According to Kerlikowske, the study is the largest to date comparing rates of early-stage invasive cancer detection and advanced-stage breast cancer diagnosis with the two screening technologies.
Diagnosis of a tumor that has grown to a more advanced stage sometimes is due to the previous screening’s failure to reveal a tumor already present. However, aggressive tumors also may arise between recommended screening intervals and be diagnosed from symptoms.
Dr. Stamatia Destounis, chair of the American College of Radiology Breast Imaging Commission, said in a statement to UPI that the study is “significant as it indicates similar findings as several others before it that women benefit from digital breast tomosynthesis,” specifically those with the densest breasts and higher-than-average breast cancer risk.
Destounis noted that women with non-dense breast tissue also benefit since the 3D imaging “reduced call backs and false alarms and needle biopsies that would be benign.”
Women experience short-term anxiety with such call backs and the 3D technique reduces the percentage of those, she said, adding that for women with dense breasts, 3D breast imaging found more small invasive cancers than digital mammography.
For the 3.6% of women in the study who clearly benefitted, Destounis added, “By detecting these cancers through screening DBT before they become advanced, we save women from aggressive treatment and avert more deaths, and also increase life years gained.”
Standard screening recommendations for mammography are geared toward the majority of women regarded to be at average risk for breast cancer.
But researchers and clinicians are working to develop new risk models to individualize screening recommendations, mindful of other factors that may increase cancer risk, including dense breasts.
Women with dense breasts have a higher proportion of connective and milk duct tissue that may cause tumors, which similarly appear opaque on mammography images and thus may go undetected.
Previously, Kerlikowske and colleagues found a three- to four-fold increased risk for a breast cancer diagnosis within five years for post-menopausal women whose breast density is 75% or more compared to women whose breast density is 25% or less.