Racial differences in three major NHL subtypes: descriptive epidemiology.

BACKGROUND

NHL (non-Hodgkin lymphoma) consists of over 60 subtypes, ranging from slow-growing to very aggressive. The three largest subtypes are DLBCL (diffuse large B-cell lymphoma), FL (follicular lymphoma), and CLL/SLL (chronic lymphocytic leukemia/small lymphocytic lymphoma). For each subtype, different racial groups have different presentations, etiologies, and prognosis patterns.

METHODS

SEER (Surveillance, Epidemiology, and End Results) data on DLBCL, FL, and CLL/SLL patients diagnosed between 1992 and 2010 were analyzed. Racial groups studied included NHW (non-Hispanic whites), HW (Hispanic whites), blacks, and API (Asians and Pacific Islanders). Patient characteristics, age-adjusted incidence rate, and survival were compared across races. Stratification and multivariate analysis were conducted.

RESULTS

There are significant racial differences for patients' characteristics, including gender, age at diagnosis, stage, lymph site, and age, and the patterns vary across subtypes. NHWs have the highest incidence rates for all three subtypes, followed by HWs (DLBCL and FL) and blacks (CLL/SLL). The dependence of the incidence rate on age and gender varies across subtypes. For all three subtypes, NHWs have the highest five-year relative survival rates, followed by HWs. When stratified by stage, racial difference is significant in multiple multivariate Cox regression analyses.

CONCLUSIONS

Racial differences exist among DLBCL, FL, and CLL/SLL patients in the U.S. in terms of characteristics, incidence, and survival. The patterns vary across subtypes. More data collection and analysis are needed to more comprehensively describe and interpret the across-race and subtype differences.