A comparison of tumour characteristics of screen-detected and interval cancers and their relationship with breast density and AJCC prognostic stage in a UK screening cohort
European Radiology, 2026
Abstract
Introduction: This study compared tumour characteristics of screen-detected and interval cancers and their relationship with breast density and AJCC prognostic stage.
Methods: In this retrospective study, women screened with mammography between 1/4/2017 and 30/3/2020 at one site were included. Tumour characteristics were compared for screen-detected and interval cancers with breast density (Volpara) and AJCC (8th edition) prognostic stage for interval cancers. Categorical variables were compared using Pearson's χ², Fisher's exact, or binomial tests.
Results: From 55,010 attendees, 723 cancers were diagnosed (463 screen-detected; 260 interval). Time to interval cancer diagnosis was longer in women with dense breasts compared with non-dense breasts (median: 767 vs 624 days; p = 0.04). Earlier stage interval cancers (< IIA) were more likely diagnosed in the second and third year compared to year 1. Retrospectively missed interval cancers were less frequent in women with dense breasts compared with true interval cancers (41.4% vs 71.9%; p < 0.01) and were more likely to be grade 3, lymph node positive and ≥ stage IIA.
Conclusion: The time to interval cancer diagnosis was longer for women with dense breasts. Interval cancers presenting within the first year after screening had the worst prognosis. Retrospectively missed interval cancers had worse prognostic features and were more likely in non-dense breasts. These findings identify an important opportunity for AI-based tools to enhance screening programmes.
