Reduced Dose Radiotherapy for the Treatment of Indolent Non-Hodgkin Lymphoma

PRIMARY OBJECTIVE: I. To show that the experimental arm \[9 gray (Gy) in 3 fractions, 8 Gy in 2 fractions, or 10 Gy in 5 fractions\] has significantly reduced acute toxicity (grade ≥ 2 adverse events at least possibly related to radiation treatment within 14 days after the end of radiation treatment \[according to Common Terminology Criteria for Adverse Events (CTCAE) version (v)5.0\] compared to 24 Gy in 12 fractions. SECONDARY OBJECTIVES: I. To evaluate patient reported quality of life. II. To evaluate response rate. III. To evaluate local control rate. IV. To evaluate relapse-free survival. EXPLORATORY OBJECTIVES: I. Financial toxicity will be assessed at the end of radiation treatment. II. Financial health care expenditure will be assessed at the end of radiation treatment III. Late toxicity. CORRELATIVE RESEARCH OBJECTIVES: I. Biopsies of enrolled patients will be evaluated for pathological assessment of cellular and genetic mutations to correlate them with disease local relapse and radiation resistance. II. Patients will have their baseline positron emission tomography (PET)/computed tomography (CT) scan undergo auto-segmentation to calculate the functional imaging 18-fluoro-deoxyglucose (FDG) metabolic tumor volume (MTV), total lesions glycolysis (TLG) and maximum standardized uptake volume (SUVmax) of the sites to be treated with involved-site radiation therapy (ISRT) using MIMvista platform to correlate it with disease local relapse and treatment response. OUTLINE: Patients are randomized to 1 of 2 arms. ARM I: Patients undergo reduced dose ISRT once daily (QD) over 3, 2, or 5 treatment fractions. Patients also undergo CT or PET/CT throughout the study. Patients may additionally undergo endoscopy during screening and during follow up. ARM II: Patients undergo standard of care (SOC) radiation therapy QD over 12 treatment fractions. Patients also undergo CT or PET/CT throughout the study. Patients may additionally undergo endoscopy during screening and during follow up. After completion of study treatment, patients are followed up at days 7 and 14, months 3 and 6, and then every 6 months for up to 2 years post-radiation therapy.