Exposure to Environmental Tobacco Smoke and Female Lung Cancer

Abstract

A registry-based case-control study, involving 120 cases (28 males, 92 females) of lung cancer deaths, was conducted in 1985 in the city of Guangzhou to investigate whether lifestyle factors are associated with an increased incidence of lung cancer in never-smoking individuals. The cases were matched with two control groups which consisted of non-respiratory-disease-related deaths or non-respiratory-related cancer deaths. Lifestyle factors assessed in the study include: personal history of nonmalignant respiratory diseases, practice of fresh vegetable consumption, lifetime occupation and occupational exposure histories, exposure to ETS, degree of indoor air pollution, general conditions of home residence, cooking practices and environments, and family history of cancer. Conditional logistic regression analysis demonstrated a negative association between fresh vegetable consumption and lung cancer risk in both sexes, suggesting that vegetables may exert a “protective” effect against lung cancer in humans. In males, elevated risks were found between lung cancer and occupational exposure. In females, indoor air pollution and kitchen environment were associated with risk of lung cancer. No statistically significant association was observed between lung cancer and all other factors examined, including exposure to ETS. A second case-control study was performed in 1986 to investigate the possible association between spousal smoking and lung cancer deaths. Cases consisted of 75 never-smoking females and the two control groups consisted of 128 cases of deaths due to non-tumor diseases, and 126 cases of deaths due to tumors except lung cancer. When cases were matched against “death-unrelated-to-tumor” controls, the odds ratio [OR] for ETS exposure was 1.19, as gauged by whether or not there was ETS exposure; 0.72 and 1.62, when ETS was assessed based on exposure to less than 20 or to 20 or more cigarettes/day. When ETS exposure was measured by “smokingyears”, ORs of 1.39 and 1.17 were obtained based on less than or equal to 30 years of exposure, respectively. Matching cases against “tumor-other-than-lung cancer” controls show the following: OR was 1.00 based or whether or not there was ETS exposure, 0.62 and 1.36, based on exposure to less than 20 or to 20 or more cigarettes/day, and 1.13 and 0.99, based on less than or equal to 30 years of exposure. In all cases, Ors and the calculated 95% confidence interval [CI] indices show that ETS exposure was not significantly associated with female lung cancer deaths, P>0.05. In summary, both case-control studies suggest no statistically significant association between exposure to ETS and female lung cancer in this Chinese population.