(P109) Standard Immunochemotherapy Plus Radiation vs Dose-Intense Chemotherapy With Rituximab in Stage I/II Primary Mediastinal Large B-Cell Lymphoma: A Single-Institution Experience

Michael S. Binkley, BA, Susan M. Hiniker, MD, Sharon Wu, MD, Yaso Natkunam, MD, PhD, Erik S. Mittra, MD, PhD, Ranjana H. Advani, MD, Richard T. Hoppe, MD; Stanford University

BACKGROUND: Primary mediastinal large B-cell lymphoma (PMBCL) is an uncommon variant of diffuse large B cell lymphoma, representing 2% to 3% of cases of non-Hodgkin lymphoma. Given the limited prospective data and predominantly single-center retrospective reports, the optimal chemotherapy regimen remains undefined, as does the role of radiation therapy (RT) to the mediastinum. We sought to investigate factors associated with outcomes among patients who received rituximab with standard chemotherapy (cyclophosphamide, doxorubicin, vincristine, and prednisone [R-CHOP] or etoposide, doxorubicin, cyclophosphamide, vincristine, prednisone, and bleomycin [R-VACOP-B]) with RT, compared with those who received dose-adjusted etoposide, vincristine, doxorubicin, cyclophosphamide, and rituximab (DA-EPOCH-R).

METHODS: We retrospectively analyzed patients with stage I/II PMBCL treated in the rituximab era at our institution. Exclusion criteria included stage III/IV disease and follow-up of less than 3 months. Response to chemotherapy was assessed with interim or postchemotherapy positron emission tomography-computed tomography (PET-CT) using the Deauville score. We used the Kaplan-Meier method to determine freedom from progression (FFP) and overall survival (OS). Patient characteristics were compared using Fisher’s exact test for dichotomous variables and Wilcoxon rank-sum test for continuous variables.

RESULTS: A total of 28 patients with stage I/II PMBCL were identified and treated at our institution from 2003–2012. Pretreatment characteristics included age (median 37.5, range: 20–68 yr), female gender (n = 14), performance score (median 1, range: 0–2), international prognostic indicator (IPI) score (median 1, range: 0–2), B symptoms (n = 8), elevated lactate dehydrogenase (LDH) (n = 19), bulk of disease (median 10 cm, range: 4–19.4 cm), and extranodal disease (n = 10). A total of 14 patients received six cycles of R-CHOP or 12 weeks of R-VACOP-B and RT (median 36 Gy, range: 36–45 Gy) and had a median follow-up of 94 months. Following R-CHOP/R-VACOP-B with irradiation, 5-year FFP and OS were both 100%. Also, 14 patients received four to eight cycles DA-EPOCH-R and had a median follow-up of 38 months, with one patient receiving RT (36 Gy) with postchemotherapy PET-CT Deauville score 4. Following DA-EPOCH-R, 3-year FFP and OS were both 100%. Univariate analysis found no significant association between FFP or OS with pretreatment patient characteristics, chemotherapy type, or PET-CT Deauville score ≥ 4. Acute toxicities included neutropenia (absolute neutrophil count [ANC] < 500 cells/mm³, n = 10), hospitalization for neutropenic fever (n = 6), and grade 2 radiation pneumonitis (n = 2). Late effects following RT included hypothyroidism (n = 2).

CONCLUSION: Both R-CHOP/R-VACOP-B with RT and DA-EPOCH-R demonstrate excellent outcomes. Long-term follow-up will be required to assess potential complications of contemporary RT. Our data support use of standard immunochemotherapy with RT or DA-EPOCH-R as monotherapy.

Proceedings of the 97th Annual Meeting of the American Radium Society - americanradiumsociety.org