In a randomized trial of nearly 100,000 women in Germany, 3D mammography found a larger share of breast cancers at the screening visit, but its 24% lower rate of cancers found between screenings was not statistically significant.
Three-dimensional (3D) mammography found a larger share of breast cancers at the screening visit than standard mammography in a randomized trial of nearly 100,000 women, according to results published Oct. 9, 2026, in The Lancet Oncology. Fewer women in the 3D group were diagnosed with invasive breast cancer in the two years after a normal screening, but that difference was not statistically significant, meaning it may have been due to chance.
The TOSYMA trial enrolled women aged 50 to 70 at 17 screening sites in two German states between 2018 and 2020, as part of Germany's routine breast screening program. Women were randomly assigned to one of two tests:
An earlier report from the trial, published in 2022, showed that 3D mammography found more invasive cancers at screening: 7.1 versus 4.8 per 1,000 women screened. The new analysis looked at what happened afterward, focusing on interval cancers.
Interval cancers are breast cancers diagnosed between regular screenings, after a screening result was normal. They are often more aggressive, so researchers use them to judge how well a screening test works. Researchers found them by linking participants to state cancer registries, which capture more than 95% of new breast cancers.
The researchers, led by the University of Münster, said the results add to limited evidence on how women fare after 3D screening.
About 20,000 fewer women took part than planned, which the researchers said may be related to the COVID-19 pandemic. A smaller trial makes it harder to show a statistically significant difference. The study also does not show whether 3D screening leads to fewer deaths from breast cancer. The team plans to analyze the next screening round to see whether 3D mammography reduces advanced-stage cancers more than standard mammography.
The trial was done in Germany, where women in this age range are screened every two years, so results may not translate exactly to U.S. screening schedules.
Both 3D and standard mammography are effective screening tests, and the most important step is getting screened on schedule. If you are offered 3D mammography, this trial suggests it finds a larger share of cancers at the screening visit. If you have dense breast tissue, ask whether additional imaging makes sense; CURE explains
No screening test finds every cancer. If you notice a new lump, skin change or nipple change between mammograms, contact your doctor rather than waiting for your next screening.
