Treatment of follicular lymphoma with a focus on radiotherapy

Purpose To describe the overall treatment patterns of follicular lymphoma (FL) in a single tertiary institution, with a focus on the outcomes of radiotherapy treatment in this group of patients. Methods and materials Retrospective analysis on 177 patients with FL registered from 1996 to 2011 and followed up to October 2017. Diagnosis was confirmed by histology and staging by clinical examination and imaging with positron emission tomography (PET) or computed tomography (CT) scan. Demographics, clinicopathological characteristics, treatment details and clinical outcomes were reviewed. Results Fifty-five patients (31%) had early stage and 122 (69%) had advanced stage FL. Median follow-up was 7 years and 7.5 years for early and advanced FL respectively. For advanced stage, median overall survival (OS) was 12.9 years, 5-year and 10-year OS were 77% and 63%, and 5-year and 10-yr PFS were 57% and 40% respectively. In multivariable model, moderate FLIPI, palliative RT and anti-CD20 targeted therapy were significantly associated with OS when comparing with those with high FLIPI score, no RT and no anti-CD20 targeted therapy respectively. For early stage, median OS has not reached, 5-year and 10-year OS were 79% and 74% and 5-year and 10-year progression free survival (PFS) were 64% and 52% respectively. Stage 2 non-contiguous disease had significantly poorer survival than stage 1 patients in multivariable (HR 8.19, 95%CI 1.86 – 35.98) analysis. Overall, 49 of 177 patients (27.7%) had any form of radiotherapy as part of their treatment for FL. There were no in-field alone relapses seen in all cases treated with RT. 10% in early FL had G3-4 acute toxicities with RT whilst there was no G3-4 late toxicities. In advanced FL, there were no G3-4 acute toxicities with consolidation RT and 1 G3 with salvage RT. Conclusion Various treatment modalities were used to treat FL. FL has effective response rates to RT both in early and advanced FL. Amongst early stage, Stage 2 non-contiguous disease tended to have poorer outcomes, indicating the need for more aggressive treatment strategies for this group of patients. Patients with advanced FL may benefit from RT. There were no in-field alone relapses seen in all cases treated with RT in the early or advanced stage. New prospective studies are warranted to shed light on improving the utility of RT for patients with FL. With advances in molecular medicine, imaging and treatment approaches, there is potential for better stratification of different groups for more localized versus more systemic treatments.