RecruitingPhase 1Diagnostic testMeasuring Cell-Free DNA (cfDNA) Levels in People With Follicular LymphomaThe researchers are doing this study to measure and test cell-free DNA (cfDNA) in the blood before, during, and after first-line treatment for follicular lymphoma. They will look at whether cfDNA levels are related to a person's response to the usual first-line treatment for follicular lymphoma. Researchers also want to understand how different genetic changes in follicular lymphoma relate to a person's response to the usual first-line treatment.