Overview of prognostic factors in non-Hodgkin's lymphoma.

The non-Hodgkin's lymphomas are a biologically heterogeneous group of diseases with varying clinical presentations and outcomes. A number of studies have identified variables that carried independent prognostic significance. Although several staging systems had evolved that incorporated these prognostic variables, they were still unable to predict outcome. Ideally, the object of a staging system is to predict the likelihood of treatment response, time to progression or disease-free survival, and overall survival, and to provide a way to compare the outcome of similar groups of patients among various clinical trials. The need for such a system led to the creation of prognostic models such as the M.D. Anderson Tumor Score and, more recently, the International Prognostic Index. These prognostic models may identify those patients at highest risk for treatment failure, thereby identifying those patients who may require different therapeutic approaches.