The World Health Organization classification of non-Hodgkin lymphoma (NHL) was introduced in 2001. However, its incorporation into clinical practice is not well-described. We studied the distribution of NHL subtypes in adults diagnosed from 1998 to 2011, evaluated time trends, geo-demographic correlates, and changes in 5-year overall survival (OS). We obtained data prospectively collected by the National Cancer Data Base, which covers 70% of US cancer cases. There were 596,476 patients diagnosed with NHL. The major subtypes were diffuse large B-cell (32.5%), chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL; 18.6%), follicular (17.1%), marginal zone (8.3%), mantle cell (4.1%), peripheral T-cell not-otherwise-specified (1.7%), Burkitt (1.6%), hairy cell (1.1%), lymphoplasmacytic (1.1%), and NHL not-otherwise-specified (10.8%). Over the study period, the proportion of NHL not-otherwise-specified declined by half, while marginal zone lymphoma doubled. The distribution of major and rare NHL subtypes varied according to demographics but less so geographically or by type of treatment facility. We noted several novel findings among Hispanics (lower proportion of CLL/SLL, but higher Burkitt lymphoma and nasal NK/T-cell lymphoma), Asians (higher enteropathy-associated T-cell and angioimmunoblastic T-cell lymphomas), Blacks (higher hepatosplenic T-cell lymphoma), and Native Americans (similar proportions of CLL/SLL and nasal NK/T-cell lymphoma as Asians). With the exception of peripheral T-cell not-otherwise-specified and hairy cell leukemia, 5-year OS has improved for all the major NHL subtypes.
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