OBJECTIVES: Primary * Compare the complete response rate (confirmed or unconfirmed) in patients with previously untreated aggressive non-Hodgkin's lymphoma treated with cyclophosphamide, doxorubicin, vincristine, and prednisone with vs without gemcitabine. Secondary * Compare the safety profile of these regimens in these patients. * Compare the feasibility of these regimens, defined as the proportion of courses given as scheduled, in these patients. * Compare freedom from treatment failure in patients treated with these regimens. OUTLINE: This is an open-label, randomized, multicenter study. Patients are stratified according to participating center, International Prognostic Index score (0-2 vs 3-5), and histology (B cell vs T cell). Patients are randomized to 1 of 2 treatment arms. * Arm I: Patients receive CHOP chemotherapy comprising cyclophosphamide IV, doxorubicin IV, and vincristine IV on day 1 and oral or IV prednisone on days 1-5. * Arm II: Patients receive CHOP chemotherapy as in arm I and gemcitabine IV over 30 minutes on days 1 and 8. In both arms, treatment repeats every 3 weeks for 3 courses in the absence of unacceptable toxicity or progressive disease. Patients achieving partial response or complete or unconfirmed complete response receive an additional 5 courses of therapy (for a total of 8 courses). Patients are followed every 3 months for 3 years, every 6 months for 2 years, and then annually thereafter. PROJECTED ACCRUAL: A total of 76-82 patients (38-41 per treatment arm) will be accrued for this study within 2 years.
DISEASE CHARACTERISTICS: * Histologically confirmed aggressive non-Hodgkin's lymphoma (NHL) of 1 of the following WHO subtypes: * Diffuse large B large cell lymphoma (including all clinical and morphologic variants) * Grade 3 follicular lymphoma * Extranodal T/NK cell lymphoma, nasal type * Enteropathy-type T cell lymphoma * Hepato-splenic T cell lymphoma * Peripheral T cell lymphoma, unspecified * Angioimmunoblastic lymphoma * Anaplastic large cell lymphoma, systemic type * Stage II-IV disease * At least 1 site of measurable disease (e.g., lymph node or lymph node mass) * The following subtypes are not allowed: * Mantle cell lymphoma * Burkitt's lymphoma * Precursor B or T cell lymphoma * Primary cutaneous B or T cell lymphoma * No CNS involvement by lymphoma PATIENT CHARACTERISTICS: Age * 18 to 70 Performance status * Not specified Life expectancy * Not specified Hematopoietic * WBC \> 3,000/mm\^3 * Neutrophil count \> 1,000/mm\^3 * Platelet count \> 100,000/mm\^3 Hepatic * Bilirubin \< 2.5 times normal (unless due to lymphoma) * ALT and AST \< 2.5 times normal (unless due to lymphoma) Renal * Creatinine \< 2.0 mg/dL Cardiovascular * No severe cardiac disease that would preclude study participation or limit life expectancy Pulmonary * FEV_1 and DLCO ≥ 75% of predicted (unless due to lymphoma) * No severe pulmonary disease that would preclude study participation or limit life expectancy Other * Not pregnant or nursing * Fertile patients must use effective contraception * HIV negative * No other prior or concurrent malignancy except basal cell skin cancer or carcinoma in situ of the cervix * No severe neurologic or metabolic disease that would preclude study participation or limit life expectancy * No psychological, familial, sociological, or geographical condition that would preclude study compliance and follow-up PRIOR CONCURRENT THERAPY: Biologic therapy * No concurrent monoclonal antibodies Chemotherapy * No other concurrent chemotherapy Endocrine therapy * Not specified Radiotherapy * No prior radiotherapy * No concurrent radiotherapy Surgery * Not specified Other * No prior cytotoxic agents * No prior treatment for NHL * No other concurrent anticancer therapy * No other concurrent investigational drugs