PATIENT CHARACTERISTICS: Age: Over 18 Performance status: Zubrod 0-2 Life expectancy: Not specified Hematopoietic: Not specified Hepatic: Not specified Renal: Not specified Other: No medical contraindications to CHOP chemotherapy or rituximab No prior malignancy within past 5 years except adequately treated basal cell or squamous cell skin cancer or carcinoma in situ of the cervix No AIDS or HIV Not pregnant or nursing Fertile patients must use effective contraception