Real world experience of R‐CHOP with or without consolidative radiotherapy vs DA‐EPOCH‐R in the first‐line treatment of primary mediastinal B‐cell lymphoma

Primary mediastinal large B‐cell lymphoma (PMBCL) is a distinct clinico‐pathological subtype of diffuse large B‐cell lymphoma with unclear prognostic factors and limited clinical data. Optimal treatment and role for radiotherapy is not fully defined. We performed a multicenter retrospective review of 124 patients with newly diagnosed PMBCL between 2001 and 2016. Treatment regimens were R‐CHOP (n = 41), R‐CHOP + RT (n = 37), and DA‐EPOCH‐R (n = 46). 6% (n = 3) in the DA‐EPOCH‐R group received RT. With a median follow up of 45 months, the overall 5‐year OS and PFS was 89.4% and 82.4%, respectively. The type of chemo‐radiotherapy regimen, B symptoms and Ann‐Arbor staging showed a significant association with OS on univariate analysis but only B symptoms remained prognostic (P = 0.012) after multivariate analysis. The chemo‐radiotherapy regimen, Japanese IPI and Ann‐Arbor stage was significantly associated with PFS in univariate analysis, but only chemo‐radiotherapy regimen remained significant (P = 0.02) after multivariate analysis. Patients who received R‐CHOP + RT or DA‐EPOCH‐R had better PFS than those receiving R‐CHOP alone, with 5‐year PFS of 90% vs 88.5% vs 56%, respectively (P = 0.02). In the subgroup analysis of patients with bulk (n = 71), R‐CHOP alone (n = 21) had inferior 5‐year PFS 56.6% compared to those who received R‐CHOP + RT (n = 23) 91.3% or DA‐EPOCH‐R (n = 27) 92.6% (P = 0.007). In contrast, in patients without bulk (n = 42), there was no impact of treatment regimen on PFS (P = 0.25). In conclusion, R‐CHOP + RT and DA‐EPOCH‐R provide excellent outcomes in patients with PMBCL. In patients with bulky disease, the use of DA‐EPOCH‐R may be preferable as it allows omission of RT without reduction in efficacy.