Pretreatment tumor-biopsy specimens and clinical data were obtained from 414 patients with newly diagnosed diffuse large-B-cell lymphoma who were treated at 10 institutions in North America and Europe and studied according to a protocol approved by the institutional review board of the National Cancer Institute. Among these patients, a CHOP training group consisted of 181 patients, previously described,4 (link) who were treated with anthracycline-based combinations, most often CHOP or similar regimens. The other 233 patients constituted an R-CHOP cohort that received similar chemotherapy plus rituximab. The median follow-up for the R-CHOP cohort was 2.1 years; the median follow-up for survivors was 2.8 years. A panel of expert hematopathologists confirmed the diagnosis of diffuse large-B-cell lymphoma using current World Health Organization criteria. We also analyzed data from a second cohort of 177 patients who received CHOP; these data were previously reported by the Molecular Mechanisms in Malignant Lymphomas Network Project (MMMLNP).13 (link)