The International Prognostic Index determines the outcome of patients with nodal mature T-cell lymphomas.

The World Health Organization (WHO) lymphoma classification recognises anaplastic large cell lymphoma (ALCL), angioimmunoblastic lymphoma (AIL) and peripheral T-cell lymphoma, unspecified (PTCU) as nodal mature T-cell lymphomas. Little is known about long-term outcome and prognostic factors of these diseases. A retrospective analysis on 125 patients with ALCL, AIL or PTCU was performed to evaluate outcome parameters, taking into account histological subtype and the International Prognostic Index (IPI). Median age was 54 years (range 17-90 years). Complete remission (CR) was achieved in 51% of patients. Five-year overall survival (OS) was 43%, and 5-year relapse-free survival was 69%. Five-year OS was 61% for ALCL, 45% for PTCU and 28% for AIL. With regard to the IPI, 5-year OS was 74%, 49%, 21% and 6% for the low, low-intermediate, high-intermediate and high risk groups, respectively. In the multivariate analysis, the IPI but not the histological subtype significantly predicted survival. To a large extent, the IPI score explains the differences in survival between histological subtypes of nodal mature T-cell lymphomas. The IPI may therefore be used for risk stratification in clinical trials to identify patients who would benefit most from new treatment strategies, such as high-dose chemotherapy followed by stem cell or bone marrow transplantation.