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.