Background: Oncoplastic breast-conserving surgery (OBCS) requires more complex surgical techniques than standard wide local excision (WLE) and the postoperative complication rate may be higher. Since these can have an impact on postoperative imaging, we compared imaging and biopsy results after OBCS and WLE. Methods: Findings for patients undergoing OBCS (n = 83) or standard WLE (n = 128) were compared. Numbers, indications and outcomes of mammograms, breast ultrasounds, magnetic resonance imaging scans and biopsies done within 2 years after surgery were analysed. Results: OBCS was applied for more advanced malignancy. Significantly more patients required breast ultrasound after OBCS than WLE (20/71 vs. 17/116; p = 0.024). Breast Imaging Reporting and Data System (BI-RADS) category 3 or 4 ultrasound results were found only in patients with OBCS (6/29 vs. 0/19; p = 0.034). Significantly more biopsies were required after OBCS (9/71 vs. 3/116; p = 0.006). New lumps or lumpiness were the commonest indications, and pathology confirmed fat necrosis in the majority (7/12). The rate of fat necrosis after OBCS was 18% on clinical examination (13/71), 15% with ultrasound (11/71) and 7% confirmed on pathology (5/71). Conclusion: Patients treated with OBCS require significantly more ultrasound scans and consequent biopsies than patients who underwent WLE. This is mainly due to fat necrosis developing after OBCS in the majority of cases.

Based on these long-term follow-up data, ORM is an oncologically safe treatment option.