Primary mediastinal large B-cell lymphoma: Treatment outcomes in 43 patients

Abstract

17556 Objectives: Primary mediastinal B-cell Lymphoma (PMBL) is recognized as a separate entity in the WHO classification. Treatment for PMBL is based on a combination of conventional dose chemotherapy, high dose chemotherapy and radiation therapy. The best strategy is still undefined. We conducted a retrospective analysis of patients with PBML to identify clinical prognostic factors. Methods: A retrospective analysis of 43 patients treated at Hospital do Cancer AC Camargo, Sao Paulo, Brazil, between 1989 and 2004. All patients had previous diagnosis of diffuse large B-cell lymphoma, with positive CD20 on neoplastic cells. A predominant anterior mediastinal lesion should be present. Induction chemotherapy regimens were grouped in first generation (CHOP/CHOP-like), third generation (PromaceCytabon/MACOP) and other (pediatric regimens, COP). Results: Age ranged from 16 to 82 years-old, 30 females and 13 male. Age < 35 yo was associated with a better prognosis (5 years OS - 56% × 34%, p = 0.048). Among clinical variables, female gender, stage IA-IIB, IPI 0–1, normal LDH, absence of mediastinal bulky disease were associated with better prognosis, although not statistically significant. Response rate to first generation regimens was: 37% CR (11/29), 24% PR (7/29) and 24% PD (7/29). Four patients were treated with Third generation regimens with 2 CR and 2 PR. 20 out of 25 patients with PR or CR to first line chemotherapy received mediastinal radiation therapy. More than 65% of patients had a follow up of 5 years or more. With a median follow up of 22.3 months, projected 5 year OS was 47% and for the responders the median PFS was 8,4 months. No difference in OS and PFS was observed among the three chemotherapy groups. Conclusion: Our analysis showed that response rate to first line regimens was around 60% and 25% of patients were primarily refractory to CHOP regimen. Age younger than 35 years old was associated with a better prognosis. 5 years overall survival was 45% and is in accordance with the literature. Although recent studies have demonstrated biological similarities between PMBL and Hodgkin’s Lymphoma, the prognosis of PMBL is less favorable than HL. Better understanding of the disease will help in developing more appropriate therapeutic strategies for PMBL. No significant financial relationships to disclose.