Tomosynthesis Outperforms Digital Mammography in Five-Year Study

Research shows tomosynthesis improves cancer detection rates and reduces recall rates

Conant, E

A new study in Radiology has found that the advantages of digital breast tomosynthesis (DBT) over digital mammography (DM), including increased cancer detection and fewer false positive findings, are maintained over multiple years and rounds of screening.

“As a radiologist, tomosynthesis allows viewing of the breast in multiple layers or slices,” said study lead author Emily F. Conant, MD, professor and chief of breast imaging in the Department of Radiology, Perelman School of Medicine at the University of Pennsylvania in Philadelphia. “This ability to scroll through slices of otherwise overlapping breast tissue helps us not only detect more cancers but also better characterize benign or normal areas of the breast.”

Numerous studies have shown that DBT is superior to DM for cancer detection and reducing recall rate. However, most of the published data on DBT screening have been from first round of screening, an instance when cancer detection rates and recall rates are expected to be higher than with subsequent rounds of screening. Less is known about the performance of DBT over time.

Screening Results Held Steady In A Diverse Female Population

For this study, the research team looked at outcomes for patients over a five-year stretch after they began imaging all their screening patients with DBT in the fall of 2011. The study set included more than 56,000 DBT exams, along with 10,500 prior DM exams. The researchers compared imaging findings with results from local cancer registries.

Cancer detection rates were 6 per 1,000 for DBT, compared with 5.1 per 1,000 for DM alone. Screening recall rates were 8% for DBT, compared with 10.4% for DM alone. The numbers held steady across all five years of tomosynthesis screening. Almost a third of cancers detected with DBT screening were associated with a poorer prognosis, compared with a quarter of those detected with digital mammography alone.

“We showed that the improved performance with DBT was maintained over multiple years,” Dr. Conant said. “This is the longest follow-up with cancer registry matching that has been published thus far.” 

Dr. Conant attributed the improved outcomes achieved with tomosynthesis to better visualization of both benign and malignant lesions and a reduction in tissue superimposition.

“With tomosynthesis you can remove some of the overlapping or obscuring breast tissue so that both normal and abnormal findings are better seen,” she said. “That provides both improved cancer detection and decreased false positives.”

One of the key strengths of the study was its reliance on a diverse population of women. For instance, African American women, who are known to develop more aggressive breast cancer subtypes at an earlier age, made up about half of the study group.

“We found different types of biology in the cancers detected across our diverse population and that’s an important takeaway of this paper,” Dr. Conant said. “Our results show that we can improve our screening outcomes for younger women with DBT by finding clinically important cancers earlier with fewer false positives.”

While more studies with diverse populations and long-term follow-up are needed, the initial findings underscore the strength of tomosynthesis in breast cancer screening.

“This is very promising and important data that certainly can be used to model larger trials,” Dr. Conant said.

For More Information

Access the Radiology study, “Five Consecutive Years of Screening with Digital Breast Tomosynthesis: Outcomes by Screening Year and Round.”

Conant Research Image 3
Images in a 49-year-old woman with an advanced cancer diagnosed at screening digital breast tomosynthesis (DBT) after a negative two-dimensional digital mammogram (DM) 20 months prior. (a) Bilateral DM images obtained as part of DM/DBT study. The breasts are heterogeneously dense but no abnormality was detected. (b) Craniocaudal and mediolateral oblique images of right breast from slices of the DBT portion of the screening study demonstrate a poorly defined mass at the 12-o’clock site in the right breast (circle) on both views. (c) Targeted US scan shows a corresponding, irregular 2.4-cm solid mass at 12-o’clock in right breast. US-guided core biopsy yielded an invasive ductal carcinoma that was estrogen receptor, progesterone receptor, and human epidermal growth factor receptor 2 negative (triple negative). (d) Maximum intensity projection image of right breast from contrast material–enhanced breast MRI. The large index lesion is visible as well as extensive satellites in the surrounding breast tissue. Mastectomy was performed, and additional sites of triple-negative cancer and ductal carcinoma in situ were found histologically. Axillary node dissection was negative.