Vorinostat, Rituximab, and Combination Chemotherapy in Treating Patients With Newly Diagnosed Stage II, Stage III, or Stage IV Diffuse Large B-Cell Lymphoma

Inclusion Criteria: * Patients must have biopsy proven, newly diagnosed DLBCL with stage II bulky, stage III or stage IV disease, with an International Prognostic Index (IPI) or revised (R)-IPI score greater than 0; a report providing confirmation of CD20 expression must be submitted * Adequate sections from the original diagnostic specimen must be available for submission for review by the Southwest Oncology Group (SWOG) Lymphoma Pathology Laboratory; an adequate biopsy requires sufficient tissue to establish the architecture and World Health Organization (WHO) histologic subtype with certainty; fine needle aspiration or cytology is not adequate * Patients must be offered the opportunity to consent to the correlative science studies; patients are encouraged to submit specimens for correlative studies; however, specimen submission is not a requirement for participation in the study * Patients must have measurable disease; measurable disease must be determined by computed tomography (CT) scan of chest, abdomen and pelvis performed within 28 days prior to registration; positron emission tomography (PET)/CT may be substituted for CT scan only if CT scan is of diagnostic quality and is contrast enhanced * Patients must have a unilateral bone marrow aspirate and biopsy for staging performed within 42 days prior to registration * Patients must not have clinical evidence of central nervous system involvement by lymphoma; any laboratory or radiographic tests performed within 42 days…