Rituximab in Treating Patients With Low Tumor Burden Indolent Non-Hodgkin's Lymphoma

INCLUSION CRITERIA: * Histologically confirmed non-Hodgkin's lymphoma, including 1 of the following: * Follicular grade 1 or 2 * Small lymphocytic * Marginal zone (nodal) * Marginal zone (splenic) * Mucosa-associated lymphoid tissue (MALT) * Stage III or IV disease * Must meet the following criteria for low tumor burden: * No nodal or extranodal mass at least 7 cm * Less than 3 nodal masses greater than 3 cm in diameter * No systemic symptoms or B symptoms * No splenomegaly greater than 16 cm by a computed tomography (CT) scan * No evidence of risk of compression of a vital organ (i.e., ureteral or epidural) * No leukemic phase with greater than 5,000/mm\^3 circulating lymphocytes * No cytopenias, defined as any of the following: * Platelet count less than 100,000/mm\^3 * Hemoglobin less than 10 g/dL * Absolute neutrophil count less than 1,500/mm\^3 * At least 1 objective measurable disease parameter * Abnormal positron emission tomography (PET) scans will not constitute evaluable disease unless verified by CT scan or other appropriate imaging * Age: 18 and over * Eastern Cooperative Oncology Group (ECOG) performance status 0-1 * Must meet the following criteria for labs: * Hematopoietic * Absolute neutrophil count at least 1,500/mm\^3\* * Hemoglobin at least 10 g/dL\* * Platelet count at least 100,000/mm\^3\* * NOTE: \*Without growth factor and/or transfusion support * Hepatic * Bilirubin no greater than 2…