Identifying patients most likely to benefit from routine post-operative mammogram after breast-conserving surgery

Routine post-operative mammograms (RPMs) are performed at some institutions after breast-conserving surgery (BCS) in patients who presented with malignant calcifications in order to rule out residual malignancy. However, their clinical utility and optimal application remain uncertain.

To evaluate whether patients diagnosed with breast malignancy due to calcifications on mammography benefit from RPMs after BCS.

After institutional review board approval, we conducted a retrospective cohort study of patients presenting with malignant calcifications on initial screening mammograms who underwent RPMs at our institution between 2018 and 2022. Patients with positive surgical margins or those who underwent imaging for clinical indications were excluded. Imaging findings, pathology results, and clinical characteristics were analyzed to identify factors associated with residual malignancy.

During the study period, 2054 patients underwent BCS, of whom 306 (15%) had a post-operative mammogram within three months of surgery, and 218 fitted the final inclusion category. Suspicious residual calcifications after BCS were identified in 22 of 218 patients (10%), of whom 19 underwent biopsy and 3 proceeded directly to surgery. Residual malignancy was confirmed by biopsy in 9 patients (4%), with a positive predictive value of 41%. Multivariate analysis demonstrated that younger age and the extent of calcifications on preoperative mammograms were independently associated with residual malignancy on RPM.

RPMs were found to be more beneficial for patients aged 50 years or younger, and for patients with extensive calcifications on preoperative mammograms. Tailoring RPM use to these subgroups may improve diagnostic efficiency and reduce unnecessary interventions.