3D Mammography Helps Detect Breast Cancer Earlier

A new study concludes that screening with digital breast tomosynthesis (DBT) combined with digital mammography (DM) increases breast cancer detection rates.

Researchers at the University of Pennsylvania (Philadelphia, USA) conducted a retrospective, four-year study of screening mammography metrics to determine if the improved outcomes observed after initial implementation of DBT screening are sustainable over time, and to evaluate the effect of more than one DBT screening at the individual level. In all, 44,468 screening events were performed on 23,958 unique women. The researchers then assessed the differences in outcomes between each DBT year and the DM year.

The researchers evaluated the results between groups of women with only 1, 2, or 3 DBT screenings, and also calculated the odds of recall adjusted for age, race and ethnicity, breast density, and prior mammograms. The results showed that the yearly rate of women called back for additional imaging decreased with the number of years they received three dimensional (3D) DBT mammography exams. Per 1,000 women, 130 were recalled in the first year of 3D mammography exams, 78 after two years, and only 59 after three years.

The analysis also showed that the yearly rate of women called back for additional imaging with 3D DBT mammography was consistently lower than the rate with standard 2D mammography. Concomitantly, the cancer detection rate per 1,000 women increased from 4.6 with 2D mammography to 5.5 in year one of 3D DBT mammography screenings, 5.8 in year two, and 6.1 in year three. Interval cancer rates decreased from 0.7% with the use of DM to 0.5% with the use of DBT. The study was published on February 18, 2016, in JAMA Oncology.

“We found that reduction in recall was sustainable at a population level, with additional reduction in recall as women returned for a second and third DBT examination,” concluded senior author Emily Conant, MD, and colleagues of the department of radiology and the computational breast imaging group. “These findings reaffirm that 3D mammography is a better mammogram for breast cancer screening […] and are an important step toward informing policies so that all women can receive 3D mammography for screening.”

DBT mammograms use low dose X-rays to create a 3D image of the breast, which can then be viewed in narrow slices, similarly to CT scan images. While in conventional 2D mammography overlapping tissues can mask suspicious areas, 3D images eliminate the overlap, making abnormalities easier to recognize. Experts estimate that 3D mammography will replace conventional mammography within ten years.

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