Abstract
The authors evaluated the familial aggregation of lung and other cancers in firstโdegree relatives of lung cancer patients selfโreported to be lifetime never smokers. The data, derived from a large lung cancer caseโcontrol study, included 2,465 firstโdegree relatives of 316 never smoker lung cancer cases and 2,441 firstโdegree relatives of 318 never smoker controls, frequency matched to the cases on age, gender and ethnicity. The median age of the cases and the controls was 61 years, about 2/3 were women, and about 80% were Caucasian. Overall, there was a 25% excess risk [95% CI (1.05โ1.50)] of any type of cancer among the firstโdegree relatives of cases, and case offspring exhibited a 2โfold excess cancer risk (1.03โ4.10) compared with control offspring. There was also a 44% excess risk (1.05โ1.97) of young onset cancers (before age 50) among relatives of cases. Smoking case relatives had an increased risk of any cancer [odds ratio (OR) = 1.36 (1.03โ1.81)] and a 5.52โfold risk (1.19โ25.51) of young onset lung cancer compared with smoking control relatives. Female case relatives had a 58% excess breast cancer risk (1.04โ2.43), and case mothers a 2.57โfold breast cancer risk (1.16โ4.24). A significant excess of testicular cancer was observed among case male relatives [OR = 12.32 (1.71โ88.90)], although based on only 9 cases. The age at lung cancer diagnosis tended to be earlier in case relatives (61.4, SD = 12.9) compared with control relatives (66.2, SD = 11.4; p = 0.07). Our analysis provides further evidence for the importance of genetic factors for lung cancer in never smokers. ยฉ 2007 WileyโLiss, Inc.