Purpose: Primary breast lymphoma (PBL) comprises < 1% of breast malignancies, leading to a paucity of data to guide management. We evaluated PBL recurrence patterns across two academic hospitals in the era of modern systemic-therapy and radiotherapy.
Methods: Patients diagnosed with PBL between October 1994 and June 2016 were identified. Demographic/clinical variables were assessed via primary chart review. Local control (LC) was estimated using the cumulative incidence function and overall survival (OS) using the Kaplan-Meier method.
Results: Thirty-five patients were identified. Median follow-up 5.8 years (range 0.3-17.8 years). Median age at diagnosis 66 years (range 35-86 years). Indolent versus aggressive lymphoma represented 57% (n = 20) and 43% (n = 15) of the cohort, respectively. All patients with aggressive lymphoma received systemic therapy. Thirty patients (86%) received radiotherapy (RT). Breast-only RT was used in 57% (n = 20); 23% (n = 7) received regional nodal irradiation (RNI), and 6% (n = 2) received limited-field RT. Local recurrences were observed in 3% (n = 1), contralateral breast 9% (n = 3), CNS 6% (n = 2), distant non-CNS 30% (n = 10), both local and distant 3% (n = 1). There were no regional nodal recurrences. The 6-year LC rate was 95% for indolent and 81% for aggressive subtypes. The 6-year OS rate was 87% for indolent and 70% for aggressive subtypes.
Conclusions: The majority of patients in this PBL cohort received breast-only RT with no nodal relapses, suggesting that prophylactic RNI may be unnecessary. Given the prevalence of contralateral breast involvement at diagnosis and at recurrence, vigilant surveillance of bilateral breasts may be warranted. The role of CNS prophylaxis requires further investigation.
Keywords: Breast cancer; Primary breast lymphoma; Rare malignancies.