Radiotherapy of extranodal low-grade follicular and marginal zone lymphomas: long-term follow-up of 159 patients.

Abstract

To evaluate clinical, histopathologic, and radiation (RT) dose parameters in patients with extranodal low-grade (ENLG) non-Hodgkin lymphoma (NHL) and their possible impact on local control (LC) and survival. The medical records of 159 patients with 181 histologically confirmed ENLG-NHL lesions treated at our institution were reviewed retrospectively. The predominant histological subtype (73%) was marginal zone lymphoma (MZL). Common lesion sites were the gastrointestinal tract (GIT; 33%), skin (26%), and orbit (21%). The majority of patients (88%) presented with stageI/II disease. Thirty-three (20%) lesions were treated with reduced-dose RT (≤30.6 Gy) and 148 lesions (80%) with conventional-dose RT (>30.6 Gy), with an overall median dose of 39.6 Gy (range 4-63). The median follow-up period was 72months. The 10-year local control (LC), Progression-free survival (PFS), and overall survival (OS) rates were 96, 65, and 82%, respectively. Higher overall response rate (ORR; 98% vs. 94%, p = 0.001) and complete response rate (CRR; 95% vs. 73%, p = 0.001) were observed in patients treated with conventional-dose regimens than in those treated with reduced-dose regimens. Ten-year PFS (p = 0.90) and OS (p = 0.40) was similar between the two dose groups. RT was well tolerated in both dose groups, with no grade4/5 toxicities. In the multivariate analysis, RT dose and timing (upfront or salvage) were related to LC, whereas age, histology, and complete response (CR) to RT were associated with PFS. Patient age and radiation field size impacted OS. RT is an effective and curative local treatment for early-stage FL and MZL at conventional and reduced radiation doses. Conventional-doses seems to be associated with local response improvement, without significant differences in PFS rates. Age, histology, andresponse to RT mayinfluence thePFS.