Understanding sociohistorical imprint on cancer risk by age-period-cohort decomposition in Hong Kong

Background Research on trends in cancer incidence has usually examined single sites in populations that long ago completed the economic transition. The trends in 11 cancers in three groups in the recently transitioned Hong Kong Chinese population were examined to delineate the effects of economic transition and provide generalised aetiological insights. Methods Sex-specific Poisson models were fitted 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 similar to 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 for liver cancer and lymphoma, with reaching adulthood for cervical and male nasopharyngeal cancers, and with a generation 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 intergenerational 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.