[Radiological Tumor Signs of Breast Cancer in UICC Stage I: Subanalysis of the Randomized Controlled Trial TOSYMA]

The randomized controlled, multicenter TOSYMA study showed a superiority of the combination of digital breast tomosynthesis and synthetic mammography (DBT+SM) over digital mammography (DM) in the detection rate of invasive breast cancer at stage UICC I. In this subanalysis, we compared the mammographic tumor signs of UICC I stage breast cancers detected in each study arm and stratified according to histological grade.This subanalysis included 49,462 women in the DBT+SM arm and 49,669 women in the DM arm after 1:1 randomization from July 2018 to December 2020. The mammographic abnormalities documented at the consensus conference were collected for breast cancers in stage UICC I based on various tumor signs (such as masses, microcalcifications, architectural distortions, or their combinations). The detection rates (per 10,000 screened women) were calculated with differentiation of grade 1 and grade 2 or 3 cancers.Grade 1 cancers were detected using DBT+SM in 6.5/10,000 screened women only by masses (+1.5/10,000 versus DM), in 2.4/10,000 (+1.6/10,000) by architectural distortions, and in 1.2/10,000 (+0.8/10,000) by microcalcifications. Combinations of tumor signs were present in 7.9/10,000 (+6.1/10,000) screened women. Grade 2 or 3 cancers were detected by DBT+SM in 13.7/10,000 by masses (+2.6/10,000 versus DM), in 4.9/10,000 by microcalcifications (+2.3/10,000), and in 3.6/10,000 by architectural distortions (+2.0/10,000). Combinations were present in 10.1/10,000 (+6.3/10,000) screened women.In DBT+SM screening, the detection rate of UICC I breast cancers is higher compared to DM: both, individual tumor signs and their combinations contribute to this finding. The detection rate of UICC I grade 2 or 3 cancers is higher in DBT+SM screening than in DM screening mainly due to the combination of tumor signs. · DBT+SM detects more grade 2 or 3-UICC I breast cancers than DM.. · This increase in detection rate results mainly from a combination of tumor signs.. · Nearly half of the increase relates to individual signs: masses, microcalcifications, and architectural distortions.. · Weigel S, Hense HW, Weyer-Elberich V et al. Radiological Tumor Signs of Breast Cancer in UICC Stage I: Subanalysis of the Randomized Controlled Trial TOSYMA. Rofo 2026; 198: 85-92.