Mammographic surveillance after MammoSite breast brachytherapy - Analysis of architectural patterns and additional interventions

Purpose: To report the post-treatment mammographic findings of patients who received MammoSite brachytherapy at the Medical University of South Carolina (MUSC). Materials and Methods: A total of 126 mammograms from a cohort of 38 patients who underwent MammoSite breast brachytherapy and post-treatment mammographic follow-up exclusively at MUSC are the subject of this analysis. Surveillance mammography commenced at 6 months after completion of brachytherapy and was repeated every 6 to 12 months thereafter, depending on Breast Imaging Reporting and Data System (BI-RADS) classification and further testing recommendations. Patients were clinically assessed at least every 3 months and all available data were reviewed for documentation of mammographic findings and subsequent interventions. The minimum and median follow-up was 6 and 28 months, respectively. Results: Of the 126 mammograms analyzed, 22 (17%) were classified as BI-RADS category 2, 93 (74%) as category 3, 10 (8%) as category 4, and 1 (0.8%) as category 5. Further descriptions of the BI-RADS 3 studies were: 61 (65%) "surgical changes," 30 (32%) seromas, and 2 (2%) dystrophic calcifications. Additional interventions followed 10 (11%) of BI-RADS 3 studies, all revealing benign findings. All BI-RADS 4 or 5 studies led to needle aspiration (3) or breast biopsy (8). Two biopsies were positive for malignancy, and both were classified as elsewhere breast failures. Conclusion: Mammographic architectural patterns observed after partial breast irradiation and potential differences with respect to those traditionally seen following whole breast radiotherapy have yet to be well characterized. Our experience may be of clinical utility in the counseling of patients until data from randomized trials becomes available.