Subtype-specific incidence rates of lymphoid malignancies in Hong Kong compared to the United States, 2001-2010.

Clinical studies of lymphoid malignancies (LMs) have suggested that the descriptive patterns of LMs differ in East Asia compared to Western populations. However, there are very limited available data on population-based, subtype-specific incidence rates of LMs in the East Asian population, particularly in Chinese. Using data from the Hong Kong (HK) Cancer Registry and United States (U.S.) SEER Program, we calculated and compared age-adjusted incidence rates of LM subtypes in HK to those in Whites and Asians living in the U.S. Overall and sex-specific rates were calculated for the period 2001-2010. The incidence of most subtypes was low in the HK population, with rates <1 case per 100,000 for all subtypes except for diffuse large B-cell lymphoma (3.26/100,000) and plasma cell neoplasms (1.99/100,000). Age-adjusted incidence rates of all evaluated B-cell subtypes were significantly higher in U.S. Whites compared to HK, with standardized rate ratios (SRRs) ranging from 1.6 (Burkitt lymphoma) to 9.1 (chronic lymphocytic leukemia/small lymphocytic lymphoma). Rates in U.S. Asians were generally intermediate to those in U.S. Whites and HK. Conversely, rates of extranodal NK/T-cell lymphoma were significantly lower in both U.S. Whites (SRR=0.2) and U.S. Asians (SRR=0.5) compared to HK. Our data provide new insight into the subtype-specific patterns of LMs in the Chinese population, and suggest the need for etiological studies of LMs in the East Asian population to elucidate the factors responsible for these differences in the geographic incidence patterns.