Assessment of age, period, and cohort effects of lung cancer incidence in Hong Kong and projection up to 2030 based on changing demographics.

The burden of lung cancer in Hong Kong continues to rise. We analyzed trends in lung cancer incidence and associations with age, period, and cohort from 1985 to 2019, made projections up to 2030 and examined the drivers of lung cancer incidence. We used age-period-cohort modeling to estimate age, period, and cohort effects on lung cancer incidence rates in Hong Kong between 1985 and 2019. We projected lung cancer incidence in Hong Kong from 2020 to 2030 using Bayesian age-period-cohort analysis with an integrated nested Laplace approximation. We decomposed changes in the number of lung cancer cases into population growth, population aging, and epidemiologic changes. From 1985 to 2019, the number of lung cancer incident cases in Hong Kong continued to rise, yet the age-standardized incidence rates have declined for both sexes while have fluctuated for females over the past two decades. The overall annual percentage change from 1985 to 2019 was -2.29 (95% CI, -2.53 to -2.05) for males and -0.86 (95% CI, -1.06 to -0.65) for females. Age-specific annual percentages for both sexes showed a decreasing trend in all age groups and were more pronounced for females older than 65 years and males younger than 65 years. Period effects for both sexes showed a similar monotonic downward pattern, with the downward trend slowing for females after 2000. The cohort effect declined monotonically for males and started to plateau for females after the 1945 birth cohort. It was projected that the incident cases of lung cancer in Hong Kong would continue to increase, with 4,435 male cases and 3,561 female cases in 2030. Demographic decomposition suggested that population growth and population aging play an important role in the change of lung cancer cases. Much progress has been made in reducing the incidence of lung cancer in Hong Kong, but this has been offset by demographic changes that will continue to increase the incident cases of lung cancer in Hong Kong, especially among females. There is an urgent need for continued public health policies and clinical programs for risk factor control and necessary screening.