Primary breast double-hit lymphoma management and outcomes: a real-world multicentre experience.

Background: Primary breast double-hit lymphoma (PB-DHL) is a rare, highly aggressive malignancy that poses challenges regarding accurate diagnosis and selecting optimal treatment regimens.

Methods: We retrospectively reviewed 48 cases of patients diagnosed with PB-DHL in six academic centres between June 2014 and June 2020 in China. Study-specific data were recorded, including treatment options, therapeutic evaluation, prognostic factors and relapse patterns, and the overall survival (OS) and progression-free survival (PFS) were evaluated.

Results: In total, 48 patients were enrolled, with 14 patients treated with DA-EPOCH-R/MA (rituximab, dose-adjusted etoposide, prednisone, vincristine, cyclophosphamide, doxorubicin, alternating with high-dose methotrexate and cytarabine), 18 patients treated with DA-EPOCH-R (rituximab, dose-adjusted etoposide, prednisone, vincristine, cyclophosphamide, doxorubicin), and 16 patients treated with R-HyperCVAD (rituximab, hyperfractionated cyclophosphamide, vincristine, doxorubicin, dexamethasone, alternating with cytarabine plus methotrexate). The overall 5-year OS and PFS rates were 41.7% (95% confidence interval [CI], 27.6-56.8%) and 37.5% (95% CI, 24.0-52.6%), respectively. Of the three treatment regimens, the 5-year OS was higher in DA-EPOCH-R/MA group than in the DA-EPOCH-R or R-HyperCVAD subgroups (57.1% vs. 38.9% vs. 31.3%; P = 0.016), as was the 5-year PFS (50.0% vs. 38.9% vs. 25.0%; P = 0.035). Autologous stem cell transplantation (ASCT) prolonged the OS and PFS compared with non-ASCT patients (5-year OS: 72.2% vs. 23.3%; P < 0.001; 5-year PFS: 72.2% vs. 16.7 %, P < 0.001). Multivariate analysis identified tumour size, risk stratification, treatment with DA-EPOCH-R/MA, breast irradiation, and ASCT as significant prognostic factors.

Conclusions: DA-EPOCH-R/MA is a promising regimen for PB-DHL, and breast irradiation yields complementary benefits for prognosis. ASCT significantly decreased disease relapse, providing a potential curative PB-DHL intervention and justifying ASCT as first-line therapy for young patients. More effective treatment strategies for PB-DHL patients remain encouraging.