An enhanced International Prognostic Index (NCCN-IPI) for patients with diffuse large B-cell lymphoma treated in the rituximab era

Abstract

The International Prognostic Index (IPI) has been the basis for determining prognosis in patients with aggressive non-Hodgkin lymphoma (NHL) for the past 20 years. Using raw clinical data from the National Comprehensive Cancer Network (NCCN) database collected during the rituximab era, we built an enhanced IPI with the goal of improving risk stratification. Clinical features from 1650 adults with de novo diffuse large B-cell lymphoma (DLBCL) diagnosed from 2000-2010 at 7 NCCN cancer centers were assessed for their prognostic significance, with statistical efforts to further refine the categorization of age and normalized LDH. Five predictors (age, lactate dehydrogenase (LDH), sites of involvement, Ann Arbor stage, ECOG performance status) were identified and a maximum of 8 points assigned. Four risk groups were formed: low (0-1), low-intermediate (2-3), high-intermediate (4-5), and high (6-8). Compared with the IPI, the NCCN-IPI better discriminated low- and high-risk subgroups (5-year overall survival [OS]: 96% vs 33%) than the IPI (5 year OS: 90% vs 54%), respectively. When validated using an independent cohort from the British Columbia Cancer Agency (n = 1138), it also demonstrated enhanced discrimination for both low- and high-risk patients. The NCCN-IPI is easy to apply and more powerful than the IPI for predicting survival in the rituximab era.