Primary follicular and marginal-zone lymphoma of the breast: clinical features, prognostic factors and outcome: a study by the International Extranodal Lymphoma Study Group

Background: Primary breast lymphoma (PBL) of low-grade histology is a rare disease. This multicentric retrospective study was carried out to determine clinical features, prognosis and relapse. Patients and methods: Patients with histologically proven, previously untreated follicular or marginal-zone PBL (MZL PBL) diagnosed from 1980 to 2003 were included in the study. Major end points were progression-free survival (PFS), overall survival (OS) and potential prognostic factors. Results: We collected data on 60 cases of PBL [36 follicular and 24 marginal-zone lymphoma (MZL)]. Stage was IE or IIE in 57 patients and IVE in three patients due to bilateral breast involvement. Surgery, chemotherapy and radiotherapy (RT), alone or in combination, were used as first-line treatments in 67%, 42% and 52% of patients, respectively. Overall response rate was 98%, with a 93% complete response rate. Five-year PFS were 56% for MZL and 49% for follicular PBL (P = 0.62). Relapses were mostly in distant sites (18 of 23 cases); no patients relapsed within RT fields. Conclusions: Our data showed an indolent behaviour of MZL PBL, comparable to other primary extranodal MZL. Conversely, patients with follicular PBL had inferior PFS and OS when compared with limited-stage nodal follicular non-Hodgkin's lymphomas, suggesting an adverse prognostic role of primary breast localisation in this histological subgroup