Changing patterns of Hodgkin lymphoma incidence in Singapore

A bimodal age-specific incidence pattern with a relatively high proportion of cases occurring in adolescents and young adults is a hallmark of Hodgkin lymphoma (HL) epidemiology in Western industrialized countries. The young adult incidence peak is believed to reflect the association between HL risk in young adults and an affluent childhood socioeconomic environment. However, the dynamic development of the young adult incidence peak following socioeconomic development implied by this interpretation has scarcely been demonstrated in a single population over time. We, therefore, analyzed incidence patterns of HL in Singapore between 1968 and 2004, during which time period a socioeconomic transition towards Western World lifestyles took place. As hypothesized a HL incidence peak emerged among adolescents and young adults in Singapore. Thus, in the age groups 15-19 and 20-24 years incidence rates increased annually by 7.0% (95% confidence interval 3.4%-10.7%) and 3.4% (0.1%-6.8%), respectively, in men and by 13.7% (9.1%-18.6%) and 12.2% (7.8-16.8%), respectively, in women between 1968 and 2004. However, the incidence peak remained considerably lower than what can be observed in young adults in the Western World. It remains to be determined to what extent the current lower incidence of HL in young Asian adults should be attributed to birth cohort phenomena, as would be suggested by continued increase in incidence, and to ethnic variation in HL susceptibility between Asian and non-Asian populations, respectively.