Breast Tomosynthesis may detect more cancers than mammogram alone

By Eva Martin, MD of Elm Tree Medical Inc.

Did you remember to schedule your mammogram? Are you going to start mammograms at 40? Are you going to complete your mammogram every year or every other year? Questions abound in breast cancer screening. Gone are the days of the simple “annual mammogram.” Not least amongst these are new questions regarding breast density and the new technology “tomosynthesis.” A new article published in April on JAMA online offers new insights into tomosynthesis for women with dense and nondense breasts.

The issue of breast density has only recently become a hot topic. Research has shown that mammograms are harder to read for women with dense breasts and are less likely to reveal a hidden cancer. Higher breast density has been associated with larger breast tumors and worse prognosis. Dense breasts in and of themselves may actually be a risk factor for developing cancer in the first place. Twenty-four states in the US now require radiologists to notify patients of their breast density and what this means.

Tomosynthesis is a relatively new technology that creates a 3D image of the breast using x-rays. Traditional mammograms use two x-ray images to create an image of the breast from two directions. Tomosynthesis takes eleven x-ray images from a variety of angles that are synthesized by a computer algorithm to recreate the breast in three dimensions. Researchers hope that breast tomosynthesis will improve breast cancer screening and diagnosis for women with dense breasts (and perhaps even all women).

Dr. Elizabeth Rafferty hails from L&M Radiology in West Acton, Massachusetts. After graduating from the University of Massachusetts Medical School, she completed her training as a radiologist at Massachusetts General Hospital, spending an entire year dedicated to just breast imaging. She is one of the world’s leading experts on breast tomosynthesis, so it’s no surprise that her latest article on the subject has drawn lots of attention.

Dr. Rafferty teamed up with other researchers from Massachusetts General Hospital and studied almost half a million breast imaging studies. They reviewed the findings of 278,906 digital mammograms and 173,414 digital mammograms paired with tomosynthesis. For all women, cancer detection rates were better for women who received both mammograms and tomosynthesis. Of all the imaging studies completed, 2,157 cancers were discovered. Mammogram alone detected 2.9 invasive cancers per 1,000 screens for women with dense breasts. Adding tomosynthesis increased detection to 4.2 invasive cancers per 1,000 screens. For women with nondense breasts, detection rates increased from 3 to 4 per 1,000 screens.

The study also revealed a second benefit of adding tomosynthesis- lower recall rates. When women with dense breasts received only a mammogram, 12.7% needed to come back for more imaging. When they received a mammogram and tomosynthesis, 10.9% needed more imaging. For women with nondense breasts, the recall rate dropped from 9% to 7.9%.

One group did not have a significant benefit- women with extremely dense breasts. One drawback to the study is that it was retrospective, or that it used data collected in the past instead of randomly assigning women to one group or the other and collecting the data in real time (a randomized clinical trial). Hologic provided a research grant to support the research.

The exciting news in this study was that tomosynthesis appears to benefit women with dense and nondense breasts. Whether tomosynthesis added to mammograms (or perhaps eventually replacing mammograms) will become the new standard of care is yet to be seen, but Dr. Rafferty’s important research brings us one step closer to the final determination.