Radiation Therapy and Rituximab in Treating Patients With Stage I-II Grade 1 or Grade 2 Follicular Lymphoma

Inclusion Criteria: * Newly diagnosed patients with stage I and II follicular lymphoma, pathologically confirmed at MD Anderson Cancer Center (MDACC) to be grade 1 or 2 * Prophylactic use of lamivudine in patients that have antibody positive (+), but no active infection will be up to the treating physician * Absolute neutrophil count (ANC) \>= 1000/mm\^3; this value must be obtained within four weeks before protocol entry * Platelets \>= 80,000/mm\^3; this value must be obtained within four weeks before protocol entry * Hemoglobin \>= 8 g/dL; this value must be obtained within four weeks before protocol entry * Bilirubin =\< 1.5 times the upper limit of normal (ULN); this value must be obtained within four weeks before protocol entry * Alanine aminotransferase (ALT) =\< 2 times the ULN or aspartate aminotransferase (AST) =\< 2 times the ULN; these values must be obtained within four weeks before protocol entry * Performance status \>= 2 * Patients are required to have adequate renal function as indicated by a serum creatinine =\< 2.5 mg/dL; this value must be obtained within four weeks before protocol entry * No prior known allergic reaction to monoclonal antibodies * Male patients must agree to use a barrier method of contraception or agree to abstain from heterosexual activity for the duration of the study * Female patients must be willing to use two adequate barrier methods of contraception to prevent pregnancy or agree to abstain from heterosexual activity throughout the…