The Study: The idea is that tomosynthesis, even alone, provides better views of the breast tissue and can increase the accuracy and sensitivity of screening over traditional 2D mammography. While there have been multiple large prospective studies, the To-Be trial is the first to randomize women to either standard digital mammography or tomosynthesis. In the study, women participating in breast screening in Bergen, Norway were randomized at the time of screening to tomosynthesis or digital mammography. Importantly, the technology used—and reader experience—was “first-generation.” Almost 30,000 women (twice as many as the Swedish Malmo study) were randomized to compare a primary outcome of screening-detected breast cancer. While the recall rate was lower with tomosynthesis, the rates of biopsy and cancer detection were no different. In addition, there were no differences in the histopathologic characteristics of the tumors detected, meaning tomosynthesis wasn’t better at detecting higher grade tumors. That, or maybe these Norwegians were less likely than Swedes to assemble the machines correctly.
Bottom Line: Women randomized to first-generation breast tomosynthesis screening had similar cancer detection rates to those who had standard digital mammography. | Hofvind, Lancet Oncol 2019