Breast Conservation Project: Clinical Outcomes of Extreme Oncoplastic Breast-Conserving Therapy Versus Mastectomy for Large and Multiple Lesions

Introduction: Patients with multiple or large malignant breast lesions are classically considered mastectomy candidates, but extreme oncoplastic breast-conservation surgery (eOBCS) has become an alternative approach. There is a paucity of outcomes data comparing eOBCS with mastectomy. Methods: We reviewed our prospectively maintained, single-institution database. We included patients with non-metastatic breast cancer with multiple ipsilateral or single large (≥ 5 cm) malignant breast lesions identified preoperatively who underwent either eOBCS or mastectomy. Patient demographics, clinicopathologic features, and surgical, oncologic, and cosmetic outcomes were evaluated. Results: Seventy-six (88%) patients underwent eOBCS and 10 (12%) underwent mastectomy. Median follow-up was 24.8 months. Mastectomy patients had larger lesions than eOBCS patients (median 70 mm vs. 32.5 mm; p = 0.06). Six (60%) index mastectomy patients underwent at least one additional surgery. For eOBCS patients, 34 (44%) required re-excision, 7 of whom underwent more than one subsequent surgery to obtain negative margins, and 6 (7.9%) ultimately underwent mastectomy. For patients undergoing additional surgery (n = 40), median time between index and final operation was 315 days for mastectomy versus 21 days for eOBCS patients (p < 0.001). Mastectomy patients more frequently experienced complications (p = 0.001) and underwent cosmetic revision (p < 0.001). There was no difference in cosmetic scores, and eOBCS patients reported less pain (p = 0.009). There were two local and three distant recurrences in the eOBCS cohort and one distant recurrence in the mastectomy group. Conclusion: Breast conservation was attainable in over 90% of eOBCS patients. Increased postoperative complications and discomfort and longer duration of surgical treatment in mastectomy patients without oncologic superiority should drive informed patient discussions.