Christopher Kelly, Marc Wilson, Lucy M. Warren, Richard Sidebottom, Mark Halling-Brown, Lin Yang, Megumi Morigami, Jenny Venton, Reena Chopra, Jane Pei‐Chen Chang, Jonathan Dixon, Fiona J. Gilbert, Daniel Golden, Elzbieta Gruzewska, Lesley Honeyfield, Amandeep Hujan, Delara Khodabakhshi, Emma Lewis, Namrata Malhotra, R. V. Mallya, Della Ogunleye, Charlotte Purdy, Rory Sayres, Marcin Sieniek, Tsvetina Stoycheva, Aminata Sy, Susan Thomas, Dominic Ward, Lihong Xi, Shawn Xu, Shravya Shetty, Ara Darzi, Kenneth C. Young, Hema Purushothaman, Lisanne Khoo, Mamatha Reddy, H. Ashrafian, Deborah Cunningham
Artificial intelligence (AI) promises to enhance breast cancer screening. Here we evaluated Google's mammography AI system (version 1.2) across two phases: a retrospective study using 115,973 mammograms from five National Health Service screening services with 39-month follow-up and prospective noninterventional feasibility deployment at 12 sites (9,266 cases). The primary endpoint was AI sensitivity and specificity versus first reader using a 5% noninferiority margin. The secondary endpoints were performance versus second or consensus readers and breast-level analyses. Retrospectively, AI achieved superior sensitivity (0.541 versus 0.437 for first reader, P < 0.001) and noninferior specificity (0.943 versus 0.952, P < 0.001). Cancer detection rate increased from 7.54 to 9.33 per 1,000 women, with AI detecting 25.0% of interval cancers. Performance was particularly strong for first screens (39.3% fewer recalls, 8.8% higher detection) and invasive cancers. No systematic demographic disparities were observed. Simulated second-reader replacement reduced reading time by 32% while increasing detection by 17.7%. Prospective deployment confirmed technical feasibility but revealed a distribution shift requiring threshold recalibration. Implementation requires adaptive calibration and continuous monitoring to ensure safety and equity.