Introduction

Lymphomas are tumors that have largely benefited from the introduction of cytotoxic chemotherapy. Treatment strategies based on intensive chemotherapy have also demonstrated improved survival of patients with relapsed lymphomas. It is necessary to identify selected populations with adverse prognostic factors that would justify such a strategy. Prognostic indices have been developed both to define therapeutic strategies and compare results of clinical trials. Such indices are usually based on retrospective studies that highlight methodological problems in prospective studies in the monoclonal antibody era. The recent development of technologies analyzing gene expression profiling also gives us new tools for both more accurate diagnosis and prognostic implications. We are also beginning to see the development of indices based on lymphoma-specific biological risk factors. Positron emission tomography using 18F-fluorodeoxyglucose should also improve assessment of tumor response and introduce new prognostic measures.

Methodology for building prognostic indices

The goals of a prognostic index (PI) are as follows:

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

2. (ii) to compare the results ofclinical trials to ascertain whether groups of patients share the same prognosis;

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

A good PI must fulfill several qualities.

It must be accurate

1. (i) It must include patients with the same lymphoma subtype.

2. […]