Background: Research on trends in cancer incidence has usually examined single sites in populations that long ago completed the economic transition. We examined trends in eleven cancers in three groups in the recently transitioned Hong Kong Chinese population to delineate the effects of economic transition and provide generalised aetiological insights.
Methods: We fitted sex-specific Poisson models to cancer incidence in Hong Kong (1974-2003) to examine age, period and birth cohort effects. Cancers were grouped as: hormonally-modulated (including breast, endometrium, ovary and prostate), infection-related (cervix, liver, nasopharynx, lymphoma and stomach) and lifestyle-related (colorectum and lung).
Results: Age-standardised incidence of hormonally-modulated female cancers increased for the first generation (women born ~1940) to experience puberty in the transitioning environment of Hong Kong. Prostate cancer incidence increased, despite a downturn for the first generation growing up in Hong Kong. Incidence of infection-related cancers decreased, mainly due to birth cohort effects; coinciding with birth in Hong Kong for liver cancer and lymphoma, with reaching adulthood in Hong Kong for cervix and male nasopharynx cancers, and with a generation in Hong Kong for stomach cancer. Lifestyle-related cancers had sex-specific declines by birth cohort.
Conclusion: With economic transition and the associated lifestyle changes, environmentally determined levels of pubertal female hormones may drive inter-generational increases in hormonally-related female cancers. Economic development, via improved living conditions, may also reduce infection-related cancers, possibly including prostate cancer, however the effects depend on transmission dynamics and perhaps specific public health initiatives. In traditional societies, males may benefit from economic development sooner than females.