Predicting the outcome in non-Hodgkin lymphoma with molecular markers.

The World Health Organization classification divides non-Hodgkin lymphomas into B-cell, T-cell and natural killer-cell lymphomas. They are heterogeneous in epidemiology, histopathology and outcome. Clinical prognostic indices rely only on patient factors and staging. Molecular prognostic markers reflect the intrinsic lymphoma biology, measure tumour load and may provide novel therapeutic targets. Lymphomagenesis involves mutations, deletions or dysregulations of genes critical in the control of cell cycle and apoptosis, which are in turn prognostically important. Genome-wide gene expression profiling, either by allowing lymphomas to be classified according to different stages of lymphoid maturation, or by defining specific gene expression signatures, is also of prognostic significance. In lymphomas where viral infections of the neoplastic cells occur, quantification of viral copies is a surrogate marker for tumour load and hence prognosis. Molecular markers together with patient and clinicopathological features will provide more accurate prognostic models for risk stratification, in order to improve treatment outcome.