Evaluate the use of Early-Stage Follicular Lymphoma International ImmunoTherapy Registry and initial analysis plan to describe progression-free survival for patients with stage I-II follicular lymphoma treated with radiotherapy alone compared with radiotherapy plus immunotherapy.

The primary purpose of this study is to describe progression-free survival for patients with stage I-II follicular lymphoma treated with radiotherapy alone compared with radiotherapy plus immunotherapy. Who is it for? The registry will collect information on patients with stage I-II low grade follicular lymphoma treated with curative intent radiotherapy after staging, who received either no additional therapy or systemic therapy containing immunotherapy as part of planned combined modality therapy. Study details: Eligible patients will be identified using local patient databases, and local medical records will be reviewed. Information on demographics, staging procedures (bone marrow, CT, PET imaging), disease characteristics including WHO tumour grade (1-3b) and extranodal site, radiation treatment delivered (RT dose and method, e.g. IFRT, Involved Site RT(ISRT)), systemic therapy delivered (immunotherapy details if given and other systemic therapies if given) and follow-up information will be collected and contained within a RedCap database. It is anticipated that in coming years, new cohorts of patients with stage I-II follicular lymphoma treated with immunotherapy will become available for inclusion and that outcomes for existing cohorts will be updated. For this reason, a registry will be established, both to enable research to be conducted on retrospectively acquired data from cohorts of patients already documented and to enable updated outcome data to be uploaded for these existing cohorts. The registry will also accommodate new patient cohorts as they become available as immunotherapy becomes more widely used. Hence the registry will ultimately include a combination of retrospective and prospective elements. The registry's utilization can contribute to demonstrating the efficacy of systemic therapy in reducing the risk of death or progression and informing therapeutic decisions to enhance health outcomes in managing follicular lymphoma, where immunotherapy's historical underutilization in stage I-II FL has resulted in a lack of notable improvement in overall survival.