Comparative Long-term Study of a Large Series of Patients with Invasive Ductal Carcinoma and Invasive Lobular Carcinoma. Loco-Regional Recurrence, Metastasis, and Survival.

Our aim was to compare histologic and immunohistochemical features, surgical treatment and clinical course, including disease recurrence, distant metastases, and mortality between patients with invasive ductal carcinoma (IDC) or invasive lobular carcinoma (ILC). We included 1,745 patients operated for 1,789 breast tumors, with 1,639 IDC (1,600 patients) and 145 patients with ILC and 150 breast tumors. The median follow-up was 76 months. ILC was significantly more likely to be associated with a favorable phenotype. Prevalence of contralateral breast cancer was slightly higher for ILC patients than for IDC patients (4.0% versus 3.2%; p = n.s). ILC was more likely multifocal, estrogen receptor positive, Human Epidermal Growth Factor Receptor-2 (HER2) negative, and with lower proliferative index compared to IDC. Considering conservative surgery, ILC patients required more frequently re-excision and/or mastectomy. Prevalence of stage IIB and III stages were significantly more frequent in ILC patients than in IDC patients (37.4% versus 25.3%, p = 0.006). Positive nodes were significantly more frequent in the ILC patients (44.6% versus 37.0%, p = 0.04). After adjustment for tumor size and nodal status, frequencies of recurrence/metastasis, disease-free and specific survival were similar among patients with IDC and patients with ILC. In conclusion, women with ILC do not have worse clinical outcomes than their counterparts with IDC. Management decisions should be based on individual patient and tumor biologic characteristics rather than on lobular versus ductal histology.