Measuring Cell-Free DNA (cfDNA) Levels in People With Follicular Lymphoma

The 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.

Inclusion Criteria: * ≥18 years of age at time of signing informed consent. Consent is permitted from either the participant or from a Legally Authorized Representative (LAR) on their behalf. * Histology-confirmed follicular lymphoma grade 1-3a, verified by the enrolling institution * Ability to adhere to the study visit schedule and all the protocol requirements * Measurable FDG-avid disease * Not applicable for retrospective patients in CR Exclusion Criteria: * Patients receiving second or greater line of therapy (except in retrospective cohort of long-term survivors of FL \[i.e. \>10 years out from frontline treatment\])