Primary Breast Lymphoma: Analysis of 55 Cases of the Spanish Lymphoma Oncology Group.

Primary breast lymphoma is a rare form of localized extranodal lymphoma, which affects the mammary glands unilaterally or bilaterally, and can also affect the regional lymph nodes. We reviewed 55 patients, with disease stages IE and IIE, diagnosed in 16 Spanish institutions between 1989 and 2016. A serial of clinical variables and treatment were collected, and overall survival (OS) and progression-free survival (PFS) were calculated. Of the 55 patients, 96.4% were women with an average age of 69 years. A total of 53 patients corresponded to non-Hodgkin lymphoma (NHL), of whom 36.3% had lymph node involvement upon diagnosis. Of the patients, 58.2% were stage IE, and 41.8% were stage IIE. Treatments received included radiotherapy (36.3%), chemotherapy (85.5%), and rituximab (in 38 of the 45 patients with NHL treated with chemotherapy). In all, 82.2% of complete responses were achieved. OS and progression-free survival at 5 years in NHL patients was 76% and 73%, respectively. Current treatments (chemotherapy, immunotherapy, and radiotherapy) achieve good control of the disease, with an OS of 5 years in 80% of the patients, although there is no consensus in treatment, given the scarce incidence of these lymphomas