Rituximab and Combination Chemotherapy in Treating Older Patients With Previously Untreated B-Cell Lymphoma

DISEASE CHARACTERISTICS: * Histological diagnosis of aggressive B-cell lymphoma * Previously untreated disease * Stage I-IV disease * CD20-positive disease * Any International Prognostic Index (IPI) score * No secondary lymphoma after prior chemotherapy or radiotherapy * No primary CNS lymphoma * No primary gastrointestinal (MALT) lymphoma PATIENT CHARACTERISTICS: * ECOG performance status 0-2 * Life expectancy ≥ 3 months * AST and ALT ≤ 3 times normal unless related to lymphoma * Bilirubin ≤ 2 mg/dL unless related to lymphoma * Creatinine ≤ 2 times normal unless related to lymphoma * Fertile patients must use effective contraception * No known allergic reactions against foreign proteins * No active infections requiring systemically administered antibiotics or antiviral medications * No noncompensated heart failure * No dilatative cardiomyopathy * No coronary heart disease with ST-segment depression in ECG * No myocardial infarction during the past 6 months * No chronic lung disease with hypoxemia * No severe noncompensated hypertension * No severe noncompensated diabetes mellitus * No clinical signs of cerebral dysfunction * No severe psychiatric disease * No known HIV infection * No active chronic hepatitis B or C infection * No other concurrent diseases that exclude the administration of therapy as outlined by the study protocol PRIOR CONCURRENT THERAPY: * See Disease Characteristics * More than 12 weeks since prior clinical trial participation * No prior partici…