Risk of local failure in breast cancer patients with lobular carcinoma in situ at the final surgical margins: is re-excision necessary?

Purpose To compare the outcome of patients with invasive breast cancer both with and without lobular carcinoma in situ (LCIS)-positive/close surgical margins after breast-conserving treatment. Methods and Materials We retrospectively studied 2358 patients with T1-T2 invasive breast cancer treated with lumpectomy and radiation therapy from January 1980 to December 2009. Median age was 57 years (range, 24-91 years). There were 82 patients (3.5%) with positive/close LCIS margins ( Results The 5-year cumulative incidence of locoregional recurrence (LRR) was 3.2% (95% confidence interval [CI] 2.5%-4.1%) for the 2232 patients with LCIS-negative surgical margins (median follow-up 104 months) and 2.8% (95% CI 0.7%-10.8%) for the 82 patients with LCIS-positive/close surgical margins (median follow-up 90 months). This was not statistically significant ( P =.5). On MVA, LCIS-positive margins after the final surgery were not associated with increased risk of LRR (hazard ratio [HR] 3.4, 95% CI 0.5-24.5, P =.2). Statistically significant prognostic variables on Cox's MVA for risk of LRR included systemic therapy (HR 0.5, 95% CI 0.33-0.75, P =.001), number of positive lymph nodes (HR 1.11, 95% CI 1.05-1.18, P =.001), menopausal status (HR 0.96, 95% CI 0.95-0.98, P =.001), and histopathologic grade (grade 3 vs grade 1/2) (HR 2.6, 95% CI 1.4-4.7, P =.003). Conclusion Our results suggest that the presence of LCIS at the surgical margin after lumpectomy does not increase the risk of LRR or the final outcome. These findings suggest that re-excision or mastectomy in patients with LCIS-positive/close final surgical margins is unnecessary.