Positron Emission Tomography Using Fludeoxyglucose F 18 in Predicting Response to Treatment in Patients Who Are Receiving Rituximab and Combination Chemotherapy for Newly Diagnosed Non-Hodgkin's Lymphoma

DISEASE CHARACTERISTICS: Histologically confirmed newly diagnosed non-Hodgkin's lymphoma (NHL) Intermediate- or high-grade disease Stage I-IV disease Any of the following subtypes are allowed: Diffuse large B-cell lymphoma Anaplastic large cell lymphoma Mantle cell lymphoma Grade 3 follicular lymphoma Mediastinal B-cell lymphoma The following subtypes are not allowed: Lymphoblastic lymphoma Mycosis fungoides/Sézary's syndrome HTLV-1 associated T-cell leukemia or lymphoma Primary CNS lymphoma HIV-associated lymphoma Transformed lymphoma Burkitt's lymphoma Adequate staging of lymphoma by any of the following methods: CT scan or MRI of affected sites Unilateral or bilateral bone marrow biopsy Positive pre-treatment positron emission tomography (PET) scan Lumbar puncture Radiographically measurable disease by PET scan Any International Prognostic Index risk category allowed No prior diagnosis of another hematologic malignancy NOTE: A new classification scheme for adult non-Hodgkin's lymphoma has been adopted by PDQ. The terminology of "indolent" or "aggressive" lymphoma will replace the former terminology of "low", "intermediate", or "high" grade lymphoma. However, this protocol uses the former terminology. PATIENT CHARACTERISTICS: Age 18 and over Performance status Not specified Life expectancy Not specified Hematopoietic Absolute neutrophil count > 1,000/mm^3* Platelet count ≥ 75,000/mm^3* NOTE: *Unless due to NHL Hepatic Bilirubin ≤ 2.0 mg/dL* (excluding Gilbert's disease) NOTE: *Unless due to NHL Renal Creatinine ≤ 2.0 mg/dL (unless due to NHL) Cardiovascular Ejection fraction ≥ 45% by echocardiogram or MUGA Other Not pregnant or nursing Negative pregnancy test Fertile patients must use effective contraception HIV negative No other malignancy within the past 5 years except superficial nonmelanoma skin cancer or carcinoma in situ of the cervix No other serious co-morbid disease that would preclude study participation PRIOR CONCURRENT THERAPY: Biologic therapy No prior rituximab for NHL No concurrent filgrastim [G-CSF] during course 1 of study treatment except for patients > 70 years of age OR patients with active infection Chemotherapy No prior chemotherapy for NHL Endocrine therapy No prior steroids for NHL Radiotherapy No prior radiotherapy for NHL Concurrent consolidation radiotherapy to sites of bulky disease allowed at the discretion of the attending physician Surgery Not specified Other No other prior treatment for NHL