While previous studies have shown that digital breast tomosynthesis increases cancer detection and reduces false positive findings compared to digital mammography, few have demonstrated a consistency in these advantages over multiple years and rounds of screening.

Radiologists at the University of Pennsylvania are hoping to increase this small list and the scientific findings on the long-term benefits of DBT with their own study, which recorded and compared continuous DBT and DM exams among the same group of patients over five years — the longest follow-up trial to date.

“Of note is that the findings surround the number of ‘poor prognosis’ cancers detected with DBT compared to DM screening,” lead author Dr. Emily F. Conant, professor and chief of breast imaging in the department of radiology at the Perelman School of Medicine at the University of Pennsylvania, told HCB News. “It will be important to see if the number of these aggressive cancers decreases with longer follow-up and more rounds of screening.”
Most published data comparing DBT to DM refers to only the first round of screening, when cancer detection and recall rates are expected to be higher than with subsequent rounds. Less is known about DBT performance over time.

The team examined the outcomes of patients from over a five year period from more than 56,000 DBT exams and 10,500 prior DMs. They compared the findings with results from local cancer registries and found cancer detection rates of 6 per 1,000 for DBT and 5.1 per 1,000 for DM alone. Screening recall rates were 8% for DBT, compared with 10.4% for DM alone.

These figures held steady over five years of tomosynthesis screening, with almost a third of cancers detected with DBT connected to poorer prognosis, compared to a quarter of those found with DM alone.

In addition, the diversity of women in the study enabled researchers to find different types of biology in the cancers detected across its population. This aligns with the fact that African American women, who made up half of the study group, are known to develop more aggressive breast cancer subtypes at an earlier age.

“These are cancers that require more aggressive therapies and often have the potential to shorten a woman’s life — so they are important to find as early as possible to hopefully improve survival rates and quality of life,” said Conant.

She credits the improved outcomes with DBT to better visualization of benign and malignant lesions and a decrease in tissue superimposition, and plans to conduct further follow ups, with focus geared toward the type of cancers detected and the impact of treatment and survival.

“Ideally, these improved outcomes will be associated with the longer outcomes of decreases in the morbidity of treatments for breast cancer, and most importantly, decreases in deaths related to breast cancer,” she said. “As we continue to see long-term benefits of screening with tomosynthesis, we are confident that we will be able to to show improved cost effectiveness of DBT compared to DM screening. This type of data will further drive reimbursement for DBT in both screening and diagnostic breast imaging.”

The findings were published in Radiology.

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