FAMILIAL RISK OF LUNG-CANCER AMONG NONSMOKERS AND THEIR RELATIVES

The role of family history of lung cancer in predicting lung cancer ri sk among nonsmokers and their relatives was evaluated in a population- based family study conducted in metropolitan Detroit. Lung cancer risk factor data were collected through telephone interviews with 257 nons moking lung cancer cases 40-84 years of age diagnosed between 1984 and 1987, their 2,252 relatives, 277 nonsmoking controls, and their 2,408 relatives. Lung cancer in a first-degree relative was associated with a 7.2-fold (95% confidence interval 1.3-39.7) increased risk of lung cancer among nonsmokers in the 40- to 59-year-old age group. This sign ificant increased risk remained after adjustment for the smoking, occu pational, and medical history of each family member (relative risk = 6 .1, 95% confidence interval 1.1-33.4). Offspring of nonsmoking cases c omprised another lung cancer high risk group (relative risk = 7.2, 95% confidence interval 0.5-103). A positive family history did not incre ase lung cancer risk among nonsmokers 60-84 years of age or their rela tives. These findings suggest that susceptibility to lung cancer in fa milies of nonsmoking cases may be evident only in a subset. of relativ es of early-onset nonsmoking cases.