Fewer breast cancers during post-treatment surveillance among patients initially staged using contrast-based imaging

The role of contrast-based imaging (CBI) at diagnosis in early breast cancer remains debated. More sensitive baseline staging may identify synchronous disease that would otherwise present as early ipsilateral or contralateral events. We examined whether CBI at diagnosis is associated with differences in early locoregional outcomes.

A retrospective cohort study of women with early invasive breast cancer or ductal carcinoma in situ (DCIS). Patients were grouped according to whether they underwent CBI (CEM or MRI) at diagnosis. All underwent mammographic surveillance including contrast-enhanced mammography (CEM). Locoregional events from diagnosis to 30 June 2025 were identified and evaluated. Cox proportional hazards models to assess associations between CBI use and subsequent locoregional events were adjusted for age, calendar period, mammographic density (MD), and stage.

Among 1,106 women (594 CBI, 512 non-CBI) diagnosed between April 2015 and June 2022, there were 60 locoregional events (39 invasive, 21 DCIS). Patients who underwent CBI had fewer subsequent locoregional events. After adjustment, CBI use at diagnosis was associated with significantly lower 5-year event rates among women with invasive cancer (adjusted HR 0.50, 95% CI 0.26-0.98, p = 0.043), particularly those with Luminal A/B phenotypes, low MD, and with fewer contralateral events in invasive index cases (adjusted HR 0.19, 95% CI 0.05-0.71, p = 0.014). Features of subsequent events (including tumour grade, behaviour, and invasive size) were not found to differ between groups.

Inclusion of CBI in local staging of early breast cancer was associated with lower rates of locoregional events over five years. These findings support broader consideration of CBI use for local staging at diagnosis.