 - Gain information on the long-term efficacy of 6 courses of CHOP cyclophosphamide, doxorubicin hydrochloride, prednisone, and vincristine-like chemotherapy with vs without rituximab plus involved-field radiotherapy to primary bulky disease in young patients with good-prognosis diffuse large B-cell non-Hodgkins lymphoma treated on protocol CAN-NCIC-LY9. 