ENVIRONMENTAL TOBACCO-SMOKE AND LUNG-CANCER IN NONSMOKING WOMEN - A MULTICENTER STUDY

Objective.-To determine the relative risk (RR) of lung cancer in lifet ime never smokers associated with environmental tobacco smoke (ETS) ex posure. Design.-Multicenter population-based case-control study. Setti ng.-Five metropolitan areas in the United States: Atlanta, Ga, Houston , Tex, Los Angeles, Calif, New Orleans, La, and the San Francisco Bay Area, Calif. Patients or Other Participants or Other Participants.-Fem ale lifetime never smokers: 653 cases with histologically confirmed lu ng cancer and 1253 controls selected by random digit dialing and rando m sampling from the Health Care Financing Administration files for wom en aged 65 years and older. Main Outcome Measure.-The RR of lung cance r, estimated by adjusted odds ratio (OR) with 95% confidence interval (Cl), associated with ETS exposure. Results.-Tobacco use by spouse(s) was associated with a 30% excess risk of lung cancer: all types of pri mary lung carcinoma (adjusted OR=1.29; P<.05), pulmonary adenocarcinom a (adjusted OR=1.28; P<.05), and other primary carcinomas of the lung (adjusted OR=1.37; P=.18). An increasing RR of lung cancer was observe d with increasing pack-years of spousal ETS exposure (trend P=.03), su ch that an 80% excess risk of lung cancer was observed for subjects wi th 80 or more pack-years of exposure from a spouse (adjusted OR=1.79; 95% Cl=0.99 to 3.25). The excess risk of lung cancer among women ever exposed to ETS during adult life in the household was 24%; in the work place, 39%; and in social settings, 50%. When these sources were consi dered jointly, an increasing risk of lung cancer with increasing durat ion of exposure was observed (trend P=.001). At the highest level of e xposure, there was a 75% increased risk. No significant association wa s found between exposure during childhood to household ETS exposure fr om mother, father, or other household members; however, women who were exposed during childhood had higher RRs associated with adult-life ET S exposures than women with no childhood exposure. At the highest leve l of adult smoke-years of exposure, the ORs for women with and without childhood exposures were 3.25 (95% Cl, 2.42 to 7.46) and 1.77 (95% Cl , 0.98 to 3.19), respectively. Conclusion.-Exposure to ETS during adul t life increases risk of lung cancer in lifetime nonsmokers.