Recent Lung Cancer Patterns in Younger Age-Cohorts in Ireland

Abstract

Background: Smoking causes 85% of all lung cancers in males and 70% in females. Therefore, birth cohort analysis and annual-percent-changes (APC) in age-specific lung cancer mortality rates, particularly in the youngest age cohorts, can explain the beneficial impacts of both past and recent anti-smoking interventions. Methods: A long-term time-trend analysis (1958-2002) in lung cancer mortality rates focusing on the youngest age-cohorts (30-49 years of age) in particular was investigated in Ireland. The rates were standardised to the World Standard Population. Lung cancer mortality data were downloaded from the WHO Cancer Mortality Database to estimate APCs in death rates, using the Joinpoint regression (version 3.0) program. A simple age-cohort modelling (log-linear Poisson model) was also done, using SAS software. Results: The youngest birth cohorts (born after 1965) have almost one-fourth lower lung cancer risk relative to those born around the First World War. A more than 50% relative decline in death rates among those between 35 and 39 years of age was observed in both sexes in recent years. The youngest age-cohorts (30-39 years of age) in males also showed a significant decrease in death rates in 1998-2002 by more than 3% every five years from 1958-1962 onwards. However, death rate declines in females are slower. Conclusions: The youngest birth cohorts had the lowest lung cancer risk and also showed a significant decreasing lung cancer death rate in the most recent years. Such temporal patterns indicate the beneficial impacts of both recent and past tobacco control efforts in Ireland. However, the decline in younger female cohorts is slower. A comprehensive national tobacco control program enforced on evidence-based policies elsewhere can further accelerate a decline in death rates, especially among the younger generations.