Are Respiratory Symptoms and Chronic Airflow Limitation Really Associated with an Increased Risk of Respiratory Cancer?

Abstract

The relationship between respiratory symptoms, chronic airflow limitation and respiratory cancer was examined in a random population sample of 876 middle-aged men. All men were examined in 1974 with interview and lung function tests. Information on respiratory cancer from 1974 to June 1985 was obtained from the Danish Cancer Register. Using a multivariate Coxregression model including age as the underlying time scale and controlling for pack-years of cigarettes, cough and breathlessness were found to be significantly related to cancer—relative risks (RRs) 2.5 (95% confidence interval (Cl): 1.3–5.0) and 2.2 (95% Cl: 1.0–4.9), respectively. Phlegm, chronic phlegm, and chronic bronchitis were not related to respiratory cancer after controlling for age and smoking. Forced expiratory volume in one second (FEV1) was related to respiratory cancer, RR = 2.1 (95% Cl: 1.3–3.4) per litre under the expected FEV1 given height. Thus, our study demonstrates some relationship between respiratory symptoms and FEV1 and respiratory cancer; however, the study at the same time questions the previously demonstrated relationship between phlegm and respiratory cancer.