Can we improve upon the International Index?

The heterogeneity in outcomes in aggressive non-Hodgkin's lymphoma has prompted the development of clinical prognostic factor models which identify patients with different likelihoods of being cured of their disease. However, these clinical prognostic factor models are based on clinical features that are, in large part, surrogate variables for the biological heterogeneity of the disease. This review summarizes the development of clinical prognostic factor models and discusses some of the more recently described cellular and molecular features that may contribute to the biologic heterogeneity of aggressive NHL.