Family history of cancer and nonmalignant lung diseases as risk factors for lung cancer

Family history (FH) of lung cancer is an established risk factor for lung cancer, but the modifying effect of smoking in relatives has been rarely examined. Also, the role of FH of nonmalignant lung diseases on lung cancer risk is not well known. We examined the role of FH of cancer and nonmalignant lung diseases in lung cancer risk overall, and by personal smoking, FH of smoking and histology in 1,946 cases and 2,116 population-based controls within the Environment And Genetics in Lung cancer Etiology (EAGLE) study. Odds ratios (ORs) and 95% CI from logistic regression were calculated adjusting for age, gender, residence, education and cigarette smoking. FH of lung cancer in any family member was associated with increased lung cancer risk (OR = 1.57, 95% CI = 1.25-1.98). The odds associated with fathers', mothers' and siblings' history of lung cancer were 1.41, 2.14 and 1.53, respectively. The associations were generally stronger in never smokers, younger subjects and for the adenocarcinoma and squamous cell carcinoma subtypes. FH of chronic bronchitis and pneumonia was associated with increased (OR = 1.49, 95% CI = 1.23-1.80) and decreased (OR = 0.73, 95% CI = 0.61-0.87) lung cancer risk, respectively. FH of lung cancer and nonmalignant lung diseases affected lung cancer risk independently, and did not appear to be modified by FH of smoking