INTRODUCTION

The prognosis for lymphoma patients has improved markedly with the introduction of cytotoxic chemotherapy. Treatment strategies based upon intensified chemotherapy have also demonstrated improved survival of patients with relapsed lymphoma. It is necessary, however, to define the populations with adverse prognostic factors in order to justify such a strategy. Consequently prognostic indices have been developed from the results of clinical trials to define therapeutic strategies. Such prognostic indices have usually been based on retrospective studies, which have certain methodological problems in the new monoclonal antibody era. The recent development of technologies analyzing gene expression profiling also gives us new tools for a more accurate diagnosis with prognostic implications, using biological prognostic factors based upon lymphoma-specific risk factors. Technologies such as positron emission tomography using 18F-fluorodeoxyglucose (FDG-PET) should also improve assessment of tumor response and introduce new prognostic factors.

METHODOLOGY FOR BUILDING PROGNOSTIC INDICES

The goals of a prognostic index (PI) are multiple:

1. (1) for a single patient, to help the physician at diagnosis to predict the probable course of the disease and propose a specific treatment, to give the patient and his or her family accurate information;

2. (2) to compare the results of clinical trials in order to ascertain whether the groups of patients share the same prognosis;

3. (3) to design clinical trials in homogeneous subgroups of patients.