LAUSR

Background There are limited data on outcomes following screening breast MRI in women with a personal history of breast cancer (PHBC). Purpose To investigate outcomes and factors associated with subsequent cancers following a negative screening MRI study in women with a PHBC. Materials and Methods Consecutive women with a PHBC and a negative prevalence screening breast MRI result between August 2014 and December 2016 were retrospectively identified. Inclusion criteria were prevalence screening MRI performed as part of routine surveillance protocol (1-3 years after treatment) and follow-up data for at least 12 months. The incidence and characteristics of subsequent cancers were reviewed. Logistic regression analysis was used to investigate associations between clinical-pathologic characteristics and subsequent cancers. Performance metrics were compared among screening MRI, mammography, and US. Results A total of 993 women (mean age ± standard deviation, 53 years ± 10) were evaluated. Ten second in-breast cancers (ie, ipsilateral or contralateral) occurred at a median interval of 31.8 months (range, 13.3-44.8 months) after MRI, of which eight (80%) were ductal carcinoma in situ (DCIS) or node-negative T1 cancers. Only one node-negative T1mi (tumor ≤1 mm) second in-breast cancer visible on a mammogram was detected within 24 months of MRI. Of second in-breast cancers, 40% (four of 10) were detected only at subsequent screening MRI, which was performed a median of 30.5 months after negative prevalence screening MRI. Ten local-regional recurrences occurred at a median interval of 16.9 months (range, 6-35 months). Previous treatment for DCIS was associated with second in-breast cancers (odds ratio, 3.73; 95% CI: 1.04, 13.38; P = .04). In 1048 women who underwent prevalence screening MRI (including all Breast Imaging Reporting and Data System categories), MRI showed a lower abnormal interpretation rate and higher specificity than mammography or US (P < .001 for all). Conclusion After a negative screening MRI result, 90% of subsequent cancers were detected at intervals longer than 24 months and there was a low second in-breast cancer rate (1%). © RSNA, 2021 Supplemental material is available for this article. See also the editorial by Chang in this issue.