Genetic Determinations for Side Effects and Response Rate for Patients Receiving Chemotherapy With Diffuse Large Cell Lymphoma

Inclusion Criteria: * Histologically proven diffuse large B-cell non-Hodgkin's lymphoma according to the WHO classification, with measurable or evaluable disease * No prior therapy for NHL. Patient may be enrolled in this study after the first cycle of R-CHOP if all screening evaluations were performed prior to the first cycle of chemotherapy. * Ann Arbor stage 3 or 4 * Age greater than or equal to 18 years * Patient must give written informed consent. * A patient enrolled in another clinical trial may also enroll in this study if the other trial has an R-CHOP treatment arm and the patient is randomized to the R-CHOP only arm. Registration to this study must occur after randomization in the other trial. Exclusion Criteria: * CNS involvement * Known HIV positive * T-cell lymphoma or history of indolent NHL * Patients who will be treated with radiation therapy