PurposeThe aim is to look at the impact of margin status and outcome of invasive lobular carcinoma (ILC) treated with breast-conserving therapy (BCT).MethodsThis manuscript describes an analysis on 330 BCT in 318 patients with ILC.ResultsThe 12-year local relapse free survival (LRFS) is 89%. In multivariate analysis, positive margin status, age > 50 years, contra lateral breast cancer, and adjuvant systemic therapy were significant predictors of local relapse free survival.In a separate analysis limited to a positive margin for invasive carcinoma or carcinoma in situ, only a positive margin for invasive carcinoma was a significant predictor of local relapse free survival. This was limited to women ≤ 50 years.The 12-year disease-specific survival (DSS) was 85%. In multivariate Cox regression analysis grade 3 compared to grade 2 (HR 7.2), and a tumour size of pT2 (HR 2.5) were significant independent predictors of disease-specific survival (DFS). These factors were also relevant for distant metastasis-free survival (DMFS) and disease-free survival (DFS).ConclusionsPositive margins for invasive carcinoma seem to be a strong predictor for local recurrence in particular for women ≤ 50-years. Our study showed grade 3 and tumour size to be strong predictors of DMFS, DFS, and DSS. Margin status was not.