Dose-Adjusted EPOCH-R Is Superior to R-CHOP in Frontline Treatment of Mediastinal Large B-Cell Lymphoma

Introduction : Primary mediastinal large B-cell lymphoma (PMLBCL) is a rare, aggressive B-cell non-Hodgkin lymphoma. Dose-adjusted etoposide, prednisolone, vincristine, cyclophosphamide, doxorubicin and rituximab (DA-EPOCH-R), and rituximab, cyclophosphamide, vincristine, doxorubicin and prednisolone (RCHOP), are used as front-line treatments. Our study aims to compare the efficacy of these two regimens in newly diagnosed PMLBCL.

Methods: We retrospectively reviewed the medical records of adults (≥18 years) diagnosed with PMLBCL and treated in our center from 2010 to 2023. Baseline characteristics were compared using chi- square and Mann-Whitney U tests, as appropriate. Survival outcomes, including overall survival (OS), progression free survival (PFS) and relapse free survival (RFS) were plotted using the Kaplan-Meier method and compared using the log-rank test. OS and PFS were calculated from the date of initiation of chemotherapy to death and/or disease progression, respectively. Relapse free survival (RFS) was calculated from the date of documentation of complete response (CR) to relapse or death.

Results: Eighty-seven patients were included in the study, with a median age of 30 years (range: 18-55). The majority (86.5%) presented with bulky mediastinal disease (>7.5 cm) and 29 (32.6%) had an advanced-stage disease (stage III or IV). An International Prognostic Index (IPI) of >1 was observed in 28 (31.5%). Of the 87 patients, 48 (55.2%) were given R-CHOP, and 39 (44.8%) were given DA-EPOCH-R. Baseline characteristics were comparable between the 2 groups. The median number of chemotherapy cycles was 6 in both groups. Radiotherapy was more frequently administered to the R-CHOP group (66.7% vs 15.4%, P<0.001).

Following completion of first-line therapy (chemotherapy with or without radiotherapy), the complete response (CR) rate was significantly higher in patients treated with DA-EPOCH-R (92.3% vs 66.7%, P=0.004). After a median follow-up of 46.7 months (58.2 months for R-CHOP group and 26.8 months for DA-EPOCH-R), patients treated with DA-EPOCH-R had superior OS with 2-year OS rates of 94.4% compared to 72.1% for RCHOP (P=0.014), as well as PFS rates of 86.5% vs 62.2% (P=0.017). However, relapse-free survival (RFS) was similar in both treatment groups (2-year RFS 93.5% vs 93.3%, respectively, P=0.93). No therapy-related deaths occurred in either group.

Conclusions: In PMLBCL, front-line treatment with DA-EPOCH-R is associated with higher CR rates and superior PFS and OS than R-CHOP. However, RFS was similar between groups. Longer follow-up is required to evaluate long-term toxicities and potential late effects.