The authors evaluated the familial aggregation of lung and other cancers in first-degree relatives of lung cancer patients selfreported to be lifetime never smokers. The data, derived from a large lung cancer case-control study, included 2,465 first-degree relatives of 316 never smoker lung cancer cases and 2,441 firstdegree 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 (1.05-1.50)] of any type of cancer among the first-degree relatives of cases, and case offspring exhibited a 2-fold excess cancer risk (1.03-4.10) compared with control offspring. There was also a 44% excess risk ( Key words: lung cancer; familial aggregation; never smokers Lifetime never smokers with lung cancer likely represent a genetically susceptible subgroup distinct from ever smokers with lung cancer. 1 Familial aggregation may provide indirect evidence for a role of genetic factors in lung cancer susceptibility. The majority of studies that have evaluated familial aggregation in never-smoking lung cancer patients reported increased but not statistically significant lung cancer risk. [2][3][4][5][6][7][8][9] Several recent studies that analyzed aggregation of lung cancer in relatives of lung cancer patients reported no increased risk in first-degree relatives of never-smoking lung cancer cases. 8,9 However, one study suggested a significant 6-fold increased lung cancer risk in relatives of younger (40-59 years old) nonsmoking lung cancer patients, yet based on a small number of individuals (47 lung cancer cases and 50 controls). 3 Only a few studies have evaluated occurrence of other specific cancers in relatives of never-smoking lung cancer patients. 7,10,11 We estimated the risk of lung cancer and other cancers in firstdegree relatives of never-smoking lung cancer cases compared with first-degree relatives of matched controls, using self-reported data on family history derived from an ongoing lung cancer casecontrol study, controlling for relatives' smoking status as reported by the proband.
Material and methods
Subject recruitmentFrom September 1995 through December 2003, patients with lung cancer were accrued for an ongoing and previously described molecular epidemiological study on susceptibility markers for lung cancer from The University of Texas M. D. Anderson Cancer Center. 8,12,13 There were no age, gender, ethnic or stage restrictions. There were 316 patients with histologically confirmed lung cancer, who reported themselves to be lifetime never smokers (defined as those who had smoked less than 100 cigarettes in their lifetime). The response rate for cases was about 80%. The reasons for refusal to participate included patient too ill, patient referred only for second opinion to M. D. Anderson Cancer Center or patient unwilling to donate blood for the study and complete the interview. Healthy controls who were also lifeti...