ECOG performance status (PS) 0-3 (restricted to ECOG PS 0-2 if >= 70 years of age) Patients must have an ECOG performance status of 0-2 Patients must have an ECOG performance status of 0 -2 STEP II: ECOG performance status 0, 1, or 2 (PS 3 allowed if secondary to pain) ECOG performance status of 2 or greater RE-REGISTRATION ELIGIBILITY CRITERIA (STEP 2): ECOG performance status 0-2 ECOG performance score 0-3 ECOG performance status 0-2 Patients must have an ECOG performance status of 0-2 CRITERIA FOR MAINTENANCE THERAPY-STEP 4: Patients must have an ECOG performance status of 0-3 Eastern Cooperative Oncology Group (ECOG) performance status =< 2 (Karnofsky >= 60%) unless due to neurologic deficits caused by CNS lymphoma with the following exceptions: patients with ECOG performance status (PS) = 4 where neurologic deficits are unlikely to resolve with tumor resolution and may cause clinical management problems are excluded Performance status of 0, 1 or 2 within 28 days prior to registration ECOG performance status 0 or 1 ECOG performance status 0-2 Performance status 0, 1 or 2 Patients with ECOG performance grade of 3 or 4