Pegfilgrastim and Rituximab in Treating Patients With Untreated, Relapsed, or Refractory Follicular Lymphoma, Small Lymphocytic Lymphoma, or Marginal Zone Lymphoma

Inclusion Criteria: * Untreated or relapsed/refractory follicular, SLL or MZL (i.e. no limit to number of prior treatments as long as patients meet other study criteria) * Eastern Cooperative Oncology Group (ECOG) performance status 0 or 1 * Measurable tumor size (at least one node measuring 4 cm\^2 in bidimensional measurement) * Expected survival of \> 6 months * Prior rituximab or other monoclonal immunotherapy permitted and eligible for rituximab monotherapy * Full recovery from any significant toxicity associated with prior surgery, radiation therapy, chemotherapy, or immunotherapy * Absolute neutrophil count \> 1.0 x 10\^9/L * Platelets \> 50 x 10\^9/L * Patients may receive erythropoietin growth factors to maintain adequate hemoglobin levels (\>= 8.0 mg/dl) * Creatinine \< 1.5 x upper normal levels (UNL) * Total bilirubin \< 1.5 mg/dL (\> 25.65 umol/L) * Aspartate aminotransferase \< 5 x UNL * Alkaline phosphatase \< 5 x UNL * Informed consent approved in institutional review board (lRB) * CD20+ B-cell lymphoma Exclusion Criteria: * Prior history of human immunodeficiency virus (HIV)-positivity (routine HIV testing is required pretreatment) * Serious non-malignant disease (e.g. active uncontrolled bacterial, viral, or fungal infections) or other conditions which, in the opinion of the principal investigator would compromise other protocol objectives * Presence of central nervous system (CNS) lymphoma * Chemotherapy within 4 weeks of the first scheduled study treatme…