Extreme Oncoplasty: Avoiding Mastectomy and Expanding the Limits of Breast Conservation—A Comparative Study of 718 Patients

BACKGROUND: For many years, large, multifocal/multicentric tumors have routinely been treated with mastectomy. Extreme oncoplastic breast-conserving surgery attempts to achieve complete oncologic resection of large tumors while preserving the natural shape, symmetry, and function of breasts. This paper compares recurrence and survival probabilities for extreme and standard (≤50 mm) tumors. METHODS: A prospective oncoplastic database accrued between 2008 and 2025 was queried for patients with breast cancer treated with reduction mammoplasty and whole breast irradiation. In total, 340 patients with extreme tumors >50 mm were compared with 378 patients with standard tumors ≤50 mm. Demographic and biologic factors and recurrence and survival probabilities were compared. RESULTS: Biologic factors were statistically similar for both groups. Negative margins, defined as no ink on tumor, were achieved in 96.8% of standard and 92.6% of extreme cases (p = 0.01). Mean tumor span was 26.3 mm for standard and 74.3 mm for extreme cases (p < 0.001). Re-excision rates were 5.6 and 10.9%, for standard and extreme cases, respectively (p = 0.01). The 5-year local recurrence probability was 1.44% for standard cases versus 3.37% for extreme cases (p = 0.067). Distant recurrence, breast cancer-specific survival, and overall survival did not differ significantly. CONCLUSIONS: Extreme oncoplasty followed by whole breast irradiation allows safe breast conservation in selected patients with large, >50 mm, multifocal/multicentric tumors, achieving local and distant recurrence and survival outcomes comparable to those of standard oncoplastic cases. When technically feasible, breast conservation with extreme oncoplastic reconstruction should be considered a valid alternative to mastectomy in appropriately selected patients.