Role of local treatment in primary breast B-cell non-Hodgkin's lymphoma: a propensity score matching-based analysis from SEER database.

Primary breast lymphoma (PBL) has been defined as disease localized to breast with or without ipsilateral axillary nodal involvement. Primary breast B-cell non-Hodgkin's lymphoma is rare to be diagnosed clinically. The role of surgery and radiotherapy (RT) as local treatment is unclear. The aim of this study was to evaluate the prognostic factors and investigate the effect of local treatment in patients with primary breast B-cell non-Hodgkin's lymphoma.We identified patients with primary breast B-cell non-Hodgkin's lymphoma diagnosed between 1998 and 2015 in the Surveillance, Epidemiology, and End Results (SEER) database. Propensity score matching (PSM) was performed to reduce possible bias between groups. The overall survival (OS) and disease-specific survival (DSS) were calculated using the Kaplan-Meier method. Multivariate Cox regression analysis was used to identify independent prognostic factors.Altogether 956 patients with primary breast B-cell non-Hodgkin's lymphoma were included. Most patients were white women over the age of 60. The most common histological type was diffuse large B cell lymphoma (DLBCL), and most patients present with stage I disease. Furthermore, old age (>60 years), DLBCL histology and stage IIE disease were the statistically significant factors associated with worse OS and DSS. Surgery did not improve survival of patients, and surgery combined with RT did not achieve a better prognosis than RT alone. RT was associated with better survival in patients with stage IE DLBCL, but patients with stage IE MZL and FL and stage IIE primary breast B-cell non-Hodgkin's lymphoma could not benefit from RT.In local treatment, surgery offered no survival benefit for patients with primary breast B-cell non-Hodgkin's lymphoma, while RT is an effective choice because it can improve both OS and DSS in the stage IE DLBCL subgroup.