MILAN – Spirometry may become a useful tool for assessing lung cancer risk in smokers. The degree of airway obstruction may serve as an indicator of lung cancer risk, an Italian study suggests.

Smoking is a well-established risk factor for lung cancer. However, the significance of airflow obstruction as an independent risk factor for the development of lung cancer is less established.

“Test screening for lung cancer using airflow obstruction with a forced expiratory volume in 1 second (FEV1) <90% predicted as a cutoff is a strategy worth future consideration,“ write Dr Ugo Pastorino of the Division of Thoracic Surgery, Fondazione IRCCS, Istituto Nazionale dei Tumori, Milan, Italy and colleagues , in the European Respiratory Journal.

Cigarette smoking is the leading cause of lung cancer and is also the main cause of lung function impairment. However, the risk of lung cancer may show a greater correlation with the degree of airway obstruction than with the total dose of carcinogen exposure from cigarette smoke (as traditionally measured in pack-years).

The study evaluated data from 3,806 individuals enrolled in an early detection lung cancer trial. In total, 57 cases of lung cancer were detected over the follow-up period. Forced vital capacity (FVC) and forced expiratory volume in 1 second (FEV1) were measured at baseline in all study participants.

To better understand the relationship between FEV1 % pred and the risk of lung cancer, the doctors compared lung function results at the start of the study in the 57 patients who subsequently developed lung cancer with those from 3,749 subjects who did not develop cancer.

The risk of lung cancer was more than doubled for subjects with a FEV1 <90% of the predicted value  compared with subjects who achieved at least 90% of their predicted measurement.

Even after adjusting for confounding factors such as dose and duration of smoking, patients showing a deficit of only 10% of the predicted FEV1 multiplied their lung cancer risk by three.

”Lung function impairment represents a significant risk of developing lung cancer. In particular, a reduction of as little as 10% of FEV1% pred is associated with an almost three-fold greater lung cancer risk”, write the researchers.

In addition to smoking, there is a strong association between obstructive lung disease and lung cancer risk. These results underline the importance of baseline pulmonary function tests in lung cancer screening trials.

Spirometry might play a future role in improving patient selection for targeted lung cancer screening, the authors conclude. By targeting screening for lung cancer to those smokers with evidence of airway obstruction and/or lung parenchymal damage (emphysema), lung cancer pick-up can be substantially improved.

Reference:

Calabro E et al. Lung function predicts lung cancer risk in smokers: a tool for targeting screening programmes. Eur Respir J. 2010 Jan;35(1):146-51

Photo credit: Newcastle Hospitals