Racial patterns of extranodal natural killer/T-cell lymphoma, nasal type, in California: a population-based study.

In order to investigate whether the clinical behaviour of extranodal natural killer/T-cell lymphoma, nasal type (ENKTL) varies by race within a geographic region, we identified a total of 213 non-Hispanic whites, Hispanics and Asians/Pacific islanders (APIs) diagnosed with ENKTL in the California Cancer Registry between 2001 and 2008. The incidence and outcomes of the disease in these racial groups were analysed. The incidence rates in non-Hispanic whites, Hispanics and APIs were 0.05, 0.18 and 0.23 per 100,000 person-years, respectively, among males; and 0.03, 0.07 and 0.10 per 100,000 person-years, respectively, among females. The overall survival (OS) at 5 years was 28.6% in non-Hispanic whites, 30.4% in Hispanic, and 24.0% in APIs. In multivariate analysis, distant versus local/regional disease (Hazard Ratio [HR]=2.01, 95% confidence interval [CI]: 1.36, 2.96), initial treatment with chemotherapy plus radiotherapy (HR=0.39, 95% CI: 0.22, 0.70) or radiotherapy alone (HR=0.48, 95% CI: 0.23, 0.99) versus no therapy were associated with OS. However, OS was not affected by age, sex, race, chemotherapy alone, socioeconomic status, or human immunodeficiency virus infection. In conclusion, ENKTL is more common and clinically more similar among Hispanics and APIs than non-Hispanic whites with poor outcome in all racial groups.