Institutional review board approval was obtained for all studies, and informed consent was obtained from all participants. Table 1 describes the three studies included in the analysis. All studies were conducted by the same study staff using identical procedures, with cases ascertained through the population-based Metropolitan Detroit Cancer Surveillance System, an NCI-funded SEER registry. Studies differed only in the eligibility of cases, with the family history study focused on never smokers and cases diagnosed before the age of 50 years. The women’s epidemiology of lung diseases study focused on women, and the exploring health, ancestry, and lung epidemiology (EXHALE) study focuses on African Americans. The EXHALE study is an ongoing study. With the exception of the EXHALE study, population-based controls were chosen using random digit dialing methods. The EXHALE study relies on volunteer controls identified through research registries, advertisement, and word of mouth. All study controls were frequency matched to cases by 5-year age group, sex, and race. Questions about family history and smoking history were obtained using the same questionnaires in each study. The family history study case interview
