Background:With industrial and economic development in recent decades in South China,cancer incidence may have changed due to the changing lifestyle and environment.However,the trends of lung cancer and the roles of smoking and other environmental risk factors in the development of lung cancer in rural areas of South China remain unclear.The purpose of this study was to explore the lung cancer incidence trends and the possible causes of these trends.Methods:Joinpoint regression analysis and the age-period-cohort(APC) model were used to analyze the lung cancer incidence trends in Sihui,Guangdong province,China between 1987 and 2011,and explore the possible causes of these trends.Results:A total of 2,397 lung cancer patients were involved in this study.A 3-fold increase in the incidence of lung cancer in both sexes was observed over the 25-year period.Joinpoint regression analysis showed that while the incidence continued to increase steadily in females during the entire period,a sharp acceleration was observed in males starting in 2005.The full APC model was selected to describe age,period,and birth cohort effects on lung cancer incidence trends in Sihui.The age cohorts in both sexes showed a continuously significant increase in the relative risk(RR)of lung cancer,with a peak in the eldest age group(80-84 years).The RR of lung cancer showed a fluctuating curve in both sexes.The birth cohorts identified an increased trend in both males and females;however,males had a plateau in the youngest cohorts who were born during 1955-1969.Conclusions:Increasing trends of the incidence of lung cancer in Sihui were dominated by the effects of age and birth cohorts.Social aging,smoking,and environmental changes may play important roles in such trends. Background: With industrial and economic development in recent decades in South China, cancer caused may have changed due to the changing lifestyle and environment. However, the trends of lung cancer and the roles of smoking and other environmental risk factors in the development of lung cancer in rural areas of South China remain unclear. The purpose of this study was to explore the lung cancer incidence trends and the possible causes of these trends. Methods: Joinpoint regression analysis and the age-period-cohort (APC) model were used to analyze the lung cancer incidence trends in Sihui, Guangdong province, China between 1987 and 2011, and explore the possible causes of these trends. Results: A total of 2,397 lung cancer patients were involved in this study. A 3-fold increase in the incidence of lung cancer in both sexes was observed over the 25-year period. Joinpoint regression analysis showed that while the incidence continued to increase steadily in females during the entire period, a sharp a cceleration was observed in males starting in 2005. The full APC model was selected to describe age, period, and birth cohort effects on lung cancer incidence trends in Sihui. age cohorts in both sexes showed a continuously significant increase in the relative risk (RR ) of lung cancer, with a peak in the eldest age group (80-84 years). The RR of lung cancer showed a fluctuating curve in both sexes. The birth cohorts identified an increased trend in both males and females; however, males had a plateau in the youngest cohorts who were born during 1955-1969.Conclusions: Increasing trends of the incidence of lung cancer in Sihui were dominated by the effects of age and birth cohorts.Social aging, smoking, and environmental changes may play important roles in such trends.