Outcome of special types of luminal breast cancer.

BACKGROUND: The identification of special types of breast cancer might be of value in assessing prognosis and predicting response to therapy. METHODS: A total of 7372 consecutive patients with immunohistochemically defined luminal invasive breast cancer operated at the European Institute of Oncology between 1997 and 2005 were included. We then explored patterns of recurrence by histological type. Median follow-up was 5.8 years. RESULTS: Tumors from 5707 patients were classified as invasive ductal cancer (IDC) not otherwise specified (NOS), 851 lobular, 338 mixed ductal and lobular, 250 cribriform, 143 mucinous and 83 tubular carcinomas. Compared with IDC NOS disease-free survival (DFS) was significantly longer in patients with cribriform tumors [5-year DFS 97.9% versus 87.4%; hazard ratio (HR) = 0.48; P = 0.015) and in pooled cribriform plus tubular carcinomas (5-year DFS 98.7% versus 87.4%; HR = 0.45; P = 0.005). Mucinous tumors presented similar DFS if compared with IDC (5-year DFS 93 % versus 87.4%; HR = 1.03; P = 0.91). Conversely, DFS was poorer for patients with lobular carcinoma (5-year DFS 86.8% versus 87.4%; HR = 1.27; P = 0.01). CONCLUSIONS: The diagnosis of tubular, cribriform and lobular carcinomas carry distinct prognostic implications. The identification of these special types has a significant utility in luminal breast cancer and should be considered in therapeutic algorithms.