ESTRO meets Asia 2024 Congress Report

Follicular lymphoma (FL) is the most common indolent non-Hodgkin lymphoma. About a third of people with it present in the early stages (stage 1 or 2). For these patients, international guidelines suggest involved-site radiotherapy (ISRT) +/- anti-CD20 monoclonal-antibody treatment. For advanced-stage FL (stage 3 or 4), a watch-and-wait approach is recommended with consideration of starting systemic therapy in cases of high tumour burden or symptomatic disease. Radiotherapy has a curative role in early-stage FL, with doses as low as 24-30Gy exhibiting effective control. It also plays a role in the advanced stages in consolidative or palliative settings, where it is usually given in low doses of 4Gy in two fractions.

Our retrospective study looked at the management of FL in our centre. The study included 177 patients and involved a median follow-up of 7.43 years. A third of these patients had early FL. The treatment modality in this group was heterogeneous, and about 33% of these patients were treated with radiotherapy alone. In stage 2 disease, 45% with non-contiguous disease had radiotherapy alone, and this was 12% in those with contiguous disease.

Overall, there were good treatment outcomes. The median overall survival (OS) in the early stage was not reached  (5- and 10-year OS, 79% and 74%; 5- and 10-year progression-free survival (PFS), 64% and 52%, respectively). In stage 1 disease, for those who received radiotherapy alone, 5- and 10-year OS was 82.4% and 74.1%, respectively. On multivariable analysis, higher scores on the FL international prognostic index (FLIPI)  and the presence of stage 2 non-contiguous disease were correlated with poorer survival rates. Our study illustrated the heterogeneity in early-stage FL that is poorly reported in literature. There are significantly poorer survival rates in stage 2 non-contiguous disease compared with stage 1 and stage 2 contiguous disease. Hence, a different treatment strategy may be needed for stage 2 non-contiguous disease.

In advanced FL, about 70% of patients received anti-CD20 targeted therapy. Of these, 13% received some form of radiotherapy during their treatment. The median OS rate was 12.9 years, with 5- and 10-year OS of 77% and 63% and 5- and 10-year PFS of 57% and 40% respectively. In multivariable analysis, the use of anti-CD20 targeted therapy was associated with better survival rates.

Overall, radiotherapy has been underused. This finding concurs with those in the literature. In our study, only 27.7% of patients had some form of radiotherapy in their treatment. Radiotherapy is an effective treatment modality both in early and advanced FL. In our study, there were no in-field alone recurrences and treatment was well tolerated. Furthermore, recent studies that have tested the use of lower doses and modern imaging techniques mean that less toxic and more conformal radiotherapy can be achieved compared with that used previously. New prospective studies are warranted to shed light on how the utility of radiotherapy can be improved for patients with FL. With advances in molecular medicine, imaging and treatment approaches, there is potential for better stratification of different patient groups for more localised versus systemic treatments.

Dr Boon Fei Tan

Division of Radiation Oncology

National Cancer Centre, Singapore

Email: Tan.boon.fei@nccs.com.sg