Inclusion Criteria:  Pathologically confirmed CD20 positive follicular lymphoma grade 1, 2, or 3A based on 2016 WHO classification Treatment naive Age ≥ 18 years Indications for treatment confirmed Must has measurable lesion in CT or PET-CT prior to treatment Considered suitable for RCHOP, BR or R2 regimens Informed consented  Exclusion Criteria:  Transformed follicular lymphoma or 3B follicular lymphoma; HBsAg positive and / or HBcAb positive with HBV DNA titer; HCV antibody positive with HCV-RNA; or HIV positive Central nervous system or meninges involved Any drug contraindication in the treatment plan Patients judged by other researchers to be unsuitable for inclusion in the study