Introduction: Inflammation is involved in development of lung cancer and cardiovascular disease (CVD), and we hypothesize that self-reported CVD is an independent risk factor for lung cancer.
Methods: Data from the Nord-Trøndelag Health Study (1984-2008) linked to the Norwegian Cancer and Death Cause Registry were analyzed stratified by smoking status. In total, 97,087 persons (1,634,967 person years) were included (never smokers 567,575 person years, former smokers 295,685 person years, current smokers 444,922 person years, and unknown 326,785 person years) and followed for an average of 15 years. The proportional hazard model was applied to estimate the hazard ratio (HR) with a 95% confidence interval (CI) for self-reported CVD on lung cancer incidence rate adjusted for age, sex, body mass index, burden of tobacco smoking and chronic cough with phlegm.
Results: 1080 cases of lung cancer (1.1%) occurred. A total of 5981 (6.9%) participants had at baseline or developed during follow-up self-reported CVD. After adjusting for confounders, self-reported CVD was an independent risk factor for the development of lung cancer in former (HR [95% CI] 1.74 [1.11-2.73]) and current smokers (HR [95% CI] 1.38 [1.04-1.83]), but not in never smokers (HR [95% CI] 0.87 [0.34-2.23]).
Conclusions: Self-reported CVD was independently associated with increased occurrence of lung cancer in former and current smokers. CVD may be a novel risk factor for lung cancer screening.