Overview
- The Lancet published results on Feb. 20, 2026, from a Tohoku University–led randomized trial examining adjunct ultrasound in breast screening.
- About 70,000 asymptomatic women in their 40s across Japan were randomized between 2007 and 2011 to mammography alone or mammography plus ultrasound, with screenings at baseline and again two years later.
- Cancer detection increased from 0.33% with mammography alone to 0.5% with the addition of ultrasound, with more stage 0–1 cases identified in the combined arm.
- Across roughly 15 years of follow-up, stage 2 or higher cancers accounted for 26% (234/894) in the combined group versus 33% (277/843) with mammography alone, a 17% relative reduction.
- The gap in advanced cancer incidence widened 4–8 years after the first screening, and the findings may guide screening policy in Japan where dense breasts are common in women in their 40s.