Preexisting lung disease was examined as a risk factor for lung cancer in a population-based, case-control study of nonsmoking women in Missouri conducted between June 1, 1986, and April 1, 1991. A history of lung disease was reported by approximately 41% of 618 cases and 35% of 1,402 controls (odds ratio (OR) = 1.2; 95% confidence interval (Cl) 1.0-1.5. The risk was more pronounced when next-of-kin interviews were excluded (OR = 1.5). Previous lung disease was significantly related both to adenocarcinoma (OR = 1.4), which accounted for 62% of the cancers, and to all other cell types of lung cancer combined (OR = 1.8). Despite having discontinued smoking for more than 15 years, long-term ex-smokers were at a 2.2-fold risk of lung cancer compared with lifetime nonsmokers. Among lifetime nonsmokers, significant risks were noted for asthma (OR = 2.7) and pneumonia (OR = 1.5). Emphysema (OR = 2.6) and tuberculosis (OR = 2.0) were also significantly related to lung cancer, but only among former smokers. Chronic bronchitis was linked to elevated risks of nonadenocarcinomas only (OR = 2.3). Pleurisy was not reported more frequently by cases than by controls. Approximately 16% of all lung cancers among nonsmoking women could be attributed to previous lung diseases, most notably asthma, pneumonia, emphysema, and tuberculosis.

OBJECTIVES. The causes of lung cancer among nonsmokers are not clearly understood. To further evaluate the relation between passive smoke exposure and lung cancer in nonsmoking women, we conducted a population-based, case-control study. METHODS. Case patients (n = 618), identified through the Missouri Cancer Registry for the period 1986 through 1991, included 432 lifetime nonsmokers and 186 ex-smokers who had stopped at least 15 years before diagnosis or who had smoked for less than 1 pack-year. Control subjects (n = 1402) were selected from driver's license and Medicare files. RESULTS. No increased risk of lung cancer was associated with childhood passive smoke exposure. Adulthood analyses showed an increased lung cancer risk for lifetime nonsmokers with exposure of more than 40 pack-years from all household members (odds ratio [OR] = 1.3; 95% confidence interval [CI] = 1.0, 1.8) or from spouses only (OR = 1.3; 95% CI = 1.0, 1.7). When the time-weighted product of pack-years and average hours exposed per day was considered, a 30% excess risk was shown at the highest quartile of exposure among lifetime nonsmokers. CONCLUSIONS. Ours and other recent studies suggest a small but consistent increased risk of lung cancer from passive smoking. Comprehensive actions to limit smoking in public places and worksites are well-advised.