Aggregation of lung cancer in families: results from a population-based case-control study in Germany.

The authors investigated familial aggregation of lung cancer by means of a population-based case-control study, conducted in Germany between 1988 and 1993. They compared lung cancer prevalence in first degree relatives of 945 patients and 983 controls, accounting for various potential risk factors using logistic regression and generalized estimating equations. Some 83% of the study participants were male, and about 14% were below age 51 (young age group). Overall, lung cancer in parents or siblings was associated with a 1.67-fold (95% confidence interval (CI): 1.11, 2.52) increase in lung cancer risk. For the young participants, this risk was 4.75 (95% CI: 1.20, 18.77). Having multiple affected relatives (two or more) was related to a threefold risk elevation (odds ratio (OR) = 2.99, 95% CI: 0.32, 27.55). Paternal (OR = 1.64, 95% CI: 0.91, 2.96) but not maternal (OR = 0.91, 95% CI: 0.32, 2.61) lung cancer was associated with an increased risk of the disease. Lung cancer risk from smoking was particularly pronounced in the parents of cases (OR = 12.20, 95% CI: 3.34, 44.62 vs. OR = 7.93, 95% CI: 2.43, 25.91 in parents of controls). No risk elevation was detected for other smoking-related and other cancers in general. Results confirm previous findings and support the etiologic role of a genetic predisposition to lung cancer.