Changing Rates for Liver and Lung Cancers in Qidong, China

Residents of Qidong, China are undergoing a rapid fluctuation in cancer incidence rates at many organ sites, reflecting a dynamic interplay of socio-behavioral, economic, and environmental factors. This Perspective On Statistical Trends examines the China age-standardized incidence rates (CASR), as tracked by the Qidong Cancer Registry for the past 40 years, for the two leading cancer killers in Qidong, liver and lung. Both cancer types are strongly influenced by environmental factors. The CASR for liver cancer has dropped nearly 50% in the last 4 decades, in part from access to deep-well drinking water in the 1970s with consequent diminished exposure to tumor promoting microcystins produced by blue-green algae. There have also been substantive reductions in exposures to dietary aflatoxins, as economic reform in the mid-1980s fostered a wholesale change in dietary staple from maize to rice. In men, lung cancer CASR has trebled over this period, likely driven by a high prevalence of smokers (similar to 65%) and an ever increasing smoking frequency in this population. Qidong women, by contrast, rarely smoke and have exhibited a flat CASR until the past decade where lung cancer rates have now doubled. This upturn may reflect an increasing burden of indoor and outdoor air pollution.