Declining FEV1 and chronic productive cough in cigarette smokers: a 25-year prospective study of lung cancer incidence in Tecumseh, Michigan.

A community-based study has been reviewed to assess whether impaired forced expiratory volume in 1 s (FEV1) and/or the symptoms of chronic cough and sputum production predict the incidence of lung cancer, after controlling for age, sex, cigarette smoking history, and the dietary intake of carotenoids and retinoids. A cohort of 2099 women and 1857 men, 25 years of age or older, were first examined from 1962 to 1965. As of 1987, there were 60 validated lung cancers diagnosed in men (1.83 per 1000 person-years) and 17 in women (0.39 per 1000 person-years). The incidence density of lung cancer in current smokers at baseline, when compared with never smokers, was increased 5.34 (95% confidence interval, 1.74, 16.38) times in women and 4.11 (95% confidence interval, 1.63, 10.34) times in men. The risk of lung cancer increased in women and men in relation to the average daily intensity of exposure in current smokers and the duration of smoking history (< 20 years, > or = 20 years) in current and ex-smokers. When stratified by cigarette smoking intensity, subjects with chronic cough and phlegm experienced a future risk of lung cancer that was more than 3 times higher than that in the nonsymptomatic subgroup. Among the smoking women and men at entry, those in the lowest quartile of the percent predicted FEV1, after controlling for the average number of cigarettes smoked per day, experienced a risk of lung cancer that was 2.7 times that of subjects in the highest quartile. With each 10% decrease in percent predicted FEV1, the risk of lung cancer increased 1.17 times (0.96, 1.42), after controlling for age, sex, and cigarette smoking intensity at baseline. The average annual decline in FEV1 as estimated between 1962 and 1965 and 1967 and 1969 was a significant independent predictor of future lung cancer incidence after controlling for cigarette smoking history; the slope of the regression line indicated that with each decline in FEV1 of 100 ml/year, lung cancer incidence density increased 1.16 per 1000 person-years (95% confidence interval, 0.30, 2.01). Controlling for potential confounding by quartile distribution of calorie-adjusted dietary intake of vitamin A, beta-carotene, cholesterol, and fat did not weaken or alter the fundamental relationship with impaired pulmonary function. Rapidly declining ventilatory function in conjunction with persistent symptoms of chronic bronchitis in current smokers is predictive of the increased risk of lung cancer and correlates with cumulative levels of exposure to cigarette smoking.(ABSTRACT TRUNCATED AT 400 WORDS)