Surrogate endpoints in breast cancer screening trials

In The Lancet Oncology, Walter Heindel and colleagues 1 Heindel W Weigel S Gerβ J et al. Digital breast tomosynthesis plus synthesised mammography versus digital screening mammography for the detection of invasive breast cancer (TOSYMA): a multicentre, open-label, randomised, controlled, superiority trial. Lancet Oncol. 2022; 23: 601-611 Summary Full Text Full Text PDF PubMed Scopus (5) Google Scholar published the findings from the TOSYMA trial, the primary endpoints of which were detection of invasive breast cancer and invasive interval cancer detection rate at 24 months. However, these endpoints have never been validated as proper surrogate outcome measures for breast cancer mortality. 2 Jatoi I Pinsky PF Breast cancer screening trials: endpoints and overdiagnosis. J Natl Cancer Inst. 2021; 113: 1131-1135 Crossref PubMed Scopus (12) Google Scholar Screening methods that only increase breast cancer detection and decrease interval cancer detection rates might exacerbate the risk of breast cancer overdiagnosis and have no beneficial effect in decreasing breast cancer mortality. 2 Jatoi I Pinsky PF Breast cancer screening trials: endpoints and overdiagnosis. J Natl Cancer Inst. 2021; 113: 1131-1135 Crossref PubMed Scopus (12) Google Scholar Digital breast tomosynthesis plus synthesised mammography versus digital screening mammography for the detection of invasive breast cancer (TOSYMA): a multicentre, open-label, randomised, controlled, superiority trialThe results from this study indicate that the detection rate for invasive breast cancer was significantly higher with digital breast tomosynthesis plus s2D mammography than digital mammography alone. Evaluation of interval cancer rates in the follow-up study will further help to investigate incremental long-term benefits of digital breast tomosynthesis screening. Full-Text PDF Surrogate endpoints in breast cancer screening trials – Authors' replyWe appreciate Ismail Jatoi's interest in the TOSYMA study. He challenges the choice of the primary endpoints—the invasive breast cancer detection rates at screening and the following invasive interval cancer rates—as used in this randomised controlled trial comparing digital breast tomosynthesis plus synthesised two-dimensional mammography with digital mammography. Full-Text PDF