- Design
- Multicentre open-label randomised superiority trial
- Population
- About 98,700 screen-negative women aged 50–70 in Germany
- Primary outcome
- Invasive interval cancer rate over 24 months
- Effect
- 14.2 vs 18.6 per 10,000; OR 0.76 (0.55–1.06)
TOSYMA randomised women aged 50 to 70 at 17 German screening sites to digital breast tomosynthesis with synthesised 2D images or to standard digital mammography. Its first result, a higher cancer detection rate with tomosynthesis, was reported earlier. This analysis followed screen-negative women for 24 months.
Invasive interval cancers occurred in 14.2 per 10,000 after tomosynthesis and 18.6 per 10,000 after digital mammography (adjusted OR 0.76, 95% CI 0.55–1.06), which did not reach significance. In the first 12 months the difference was significant (OR 0.71, 0.52–0.97), but that was a secondary outcome.
Interval cancers are a better marker of screening benefit than detection rate alone, because extra detection can include overdiagnosis. The direction favours tomosynthesis, but the primary result is not conclusive and screening programmes have to weigh cost and reading time.
- Treat tomosynthesis as possibly reducing interval cancers, not proven to on this primary endpoint.
- Continue to investigate new breast symptoms between screens regardless of screening modality.
- Advise women that a negative screen does not exclude cancer appearing before the next round.
- Follow national screening programme policy on modality.
Why it matters
Higher detection only matters if it prevents the cancers that surface between screens.
Don't overread it
The primary endpoint did not reach significance; the 12-month finding is secondary.
The statistics, in plain English
An OR of 0.76 points to about a quarter fewer interval cancers, but the interval 0.55–1.06 crosses 1.0, so chance cannot be excluded. The significant 12-month result is a secondary outcome and weaker evidence.
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