GM-CSF With or Without Vaccine Therapy After Combination Chemotherapy and Rituximab as First-Line Therapy in Treating Patients With Stage II, Stage III, or Stage IV Diffuse Large B-Cell Lymphoma

OBJECTIVES: Primary * Compare the 3-year disease-free survival of patients with high-intermediate- or high-risk bulky stage II or stage III or IV diffuse large B-cell lymphoma treated with sargramostim (GM-CSF) with or without autologous immunoglobulin idiotype-KLH conjugate vaccine (FavId®) after combination chemotherapy comprising cyclophosphamide, doxorubicin, vincristine, prednisone, and rituximab (CHOP-R). Secondary * Compare the 2-year disease-free survival, duration of response, time to progression, overall survival, and safety in patients treated with these regimens. * Estimate the rate of immune reactivity to FavId®. OUTLINE: This is a randomized, double-blind, placebo-controlled study. Patients are stratified according to risk score (3 \[high-intermediate\] vs 4 or 5 \[high\]). * Chemotherapy: Patients receive cyclophosphamide IV, doxorubicin hydrochloride IV, vincristine IV, and rituximab IV on day 1 and oral prednisone on days 1-5. Treatment repeats every 21 days for up to 8 courses in the absence of disease progression or unacceptable toxicity. * Sargramostim (GM-CSF) with or without autologous immunoglobulin idiotype-KLH conjugate vaccine (FavId®): Patients achieving complete remission (CR) or unconfirmed CR after chemotherapy and who have FavId® available are randomized to 1 of 2 treatment arms. * Arm I: Patients receive FavId® vaccine subcutaneously (SC) on day 1. Patients also receive sargramostim (GM-CSF) SC on days 1-4. * Arm II: Patients receive placebo SC on day 1 and GM-CSF SC as in arm I. In both arms, treatment repeats once a month for 6 months and then once every 2 months for 24 months (18 total vaccinations) in the absence of disease progression or unacceptable toxicity. After completion of study treatment, patients are followed periodically for up to 2 years. PROJECTED ACCRUAL: A total of 480 patients will be accrued for this study.