International analysis of the frequency and outcomes of NK/T-cell lymphomas.

Peripheral T-cell and NK-cell lymphomas are uncommon disorders accounting for 10-15% of all non-Hodgkin lymphomas (NHL). The NHL classification project represents the first attempt to systematically study the distribution of NHL subtypes based on a collaborative international effort and it confirmed the wide geographic variation in the frequency of different subtypes of PTCL. Subsequently, the International T-cell Lymphoma Project (ITLP), the largest collaborative international effort to date, reported prevalence and outcomes of 1314 cases of PTCL from 22 institutions worldwide with central pathology review. The ITLP consortium launched a prospective study, the T-cell project, in September 2006 aimed at collecting an exhaustive clinical and biologic data set on 1000 patients with PTCL for better definition of prognostic factors that would influence outcomes of these patients. This review aims to describe the difference in frequency and outcomes for various subtypes of PTCL based on these studies.