TOSYMA Trial Reveals Impact of Tomosynthesis on Interval Breast Cancer Rates
A recent study indicates that digital breast tomosynthesis may reduce invasive interval breast cancer rates compared to standard mammography.
The TOSYMA trial involved 98,755 women aged 50-70, comparing tomosynthesis to standard mammography.
Invasive interval breast cancers occurred in 70 women in the tomosynthesis group versus 92 in the digital mammography group.
The study suggests a potential 24% reduction in interval cancers, though it did not achieve statistical significance.
A recent analysis from the TOSYMA trial has shown that screening with digital breast tomosynthesis, combined with synthesized two-dimensional mammography, resulted in fewer cases of invasive interval breast cancer over a two-year period compared to standard digital mammography. The findings were presented by Weigel et al. in The Lancet Oncology, although the reduction did not reach statistical significance.
The TOSYMA trial was a multicenter, open-label study conducted across 17 breast cancer screening sites in Germany. The trial involved women aged between 50 and 70 years, who were randomly assigned to receive either digital breast tomosynthesis plus synthesized mammography or standard digital mammography. The current analysis, known as TOSYMA-2, included a total of 98,755 women who initially received negative screening results, with a median age of 57 years.
Over the 24-month follow-up period, the results indicated that 70 women in the tomosynthesis group were diagnosed with invasive interval breast cancers, compared to 92 in the digital mammography group. This translates to rates of 14.2 and 18.6 cases per 10,000 women, respectively. Although the study observed a 24% relative reduction in the incidence of interval cancers with tomosynthesis, this finding did not achieve statistical significance (OR = 0.76; P = .11).
The implications of this study are significant for breast cancer screening practices. The data suggests that women who underwent tomosynthesis experienced a lower rate of invasive interval cancers, particularly among those returning for subsequent screenings. The study also highlighted that the sensitivity for detecting invasive breast cancer was higher with tomosynthesis (83.5%) compared to standard mammography (72.3%). However, the researchers acknowledged that disruptions caused by the COVID-19 pandemic may have impacted enrollment numbers, potentially limiting the trial's ability to detect a significant difference.
Looking ahead, further follow-up is planned to assess cumulative breast cancer incidence and the differences in advanced-stage disease as more screening rounds are conducted. The study was funded by the German Research Foundation, with Walter Heindel, MD, from the University of Münster, serving as the corresponding author.
