Incidence and outcomes of the peripheral T-cell lymphoma subtypes in the United States.

Peripheral T-cell lymphomas (PTCL) represent a small subgroup of non-Hodgkin lymphomas historically difficult to diagnose. We conducted a comprehensive assessment of 3287 PTCL cases diagnosed from 1992 to 2005 in 13 Surveillance, Epidemiology and End Results registries. Incidence trends, age-adjusted incidence rates and relative survival rates were compared across the study period, and by sex, race and age groups. From 1992 to 2005, PTCL incidence increased by 280%. Age-adjusted incidence rates were higher in males (Male/Female incidence rate ratio (IRR) 1.8) and in Blacks (Black/White IRR 1.2). Asian predominance was pronounced for extranodal NK/T-cell lymphoma, nasal type. Whites had higher 5-year survival than other racial groups for most histologic subtypes; however, the differences were not statistically significant. The variance in incidence rates and outcomes across PTCL subtypes support the pursuit of ongoing research to identify the etiology, pathophysiology, treatment patterns and differences in treatment response for PTCL subsets.