Positive Margin Rates After Breast-Conserving Surgery by Histologic Subtype: A Systematic Review and Meta-analysis Evaluating the Impact of Oncoplastic Surgery

BackgroundInvasive lobular carcinoma (ILC), the second most common histologic subtype of breast cancer, has a higher risk of positive surgical margins than invasive ductal carcinoma (IDC). Whether this risk persists for patients undergoing breast-conserving surgery (BCS) with oncoplastic approaches remains unclear. We conducted a systematic review and meta-analysis to assess positive margins following oncoplastic BCS by histologic subtype and evaluate the impact of oncoplastic surgery on positive margins in ILC.MethodsWe systematically searched the literature for articles reporting positive margin rates after oncoplastic BCS in ILC patients. Relative risks (RR) were log transformed and displayed with forest plots.ResultsEight studies, encompassing 754 ILC patients undergoing BCS (338 with oncoplastic surgery), were included. The pooled positive margin rate for ILC patients undergoing oncoplastic surgery was 31% (95% confidence interval [CI] 21-40%). Patients with ILC had a significantly higher RR for positive margins after oncoplastic BCS compared with IDC (RR 3.4, 95% CI 1.5-7.4). However, for ILC patients with larger tumors, oncoplastic BCS was associated with a significantly lower RR for positive margins compared with standard BCS (RR 0.5, 95% CI 0.3-0.9).ConclusionsInvasive lobular carcinoma patients undergoing oncoplastic BCS have higher positive margin risks than IDC patients, underscoring the need for improved preoperative imaging and systemic therapies. However, the addition of oncoplastic surgery to BCS reduces positive margin rates compared with standard BCS in ILC patients, particularly for larger tumors. These findings highlight the role of oncoplastic surgery as an important technique to optimize outcomes for those at high risk of positive margins.