Lung Cancer in patients with COPD: Incidence and predicting factors

BACKGROUND
Little is known about the clinical factors associated with development of lung cancer in patients with Chronic Obstructive Pulmonary Disease (COPD), although airway obstruction and emphysema have been identified as possible risk factors.

OBJECTIVE
To explore incidence, histological type and factors associated with development of lung cancer diagnosis in a cohort of COPD outpatients attending a pulmonary clinic.

METHODS
A cohort of 2507 patients without initial clinical or radiological evidence of lung cancer was followed a median of 60 months (30-90). At baseline, anthropometrics, smoking history, lung function and body composition were recorded. Time to diagnosis and histological type of lung cancer was then registered. Cox analysis was used to explore factors associated with lung cancer diagnosis.

RESULTS
A total of 215 of the 2507 COPD patients developed lung cancer (incidence density of 16.7 cases/1000 person-years). The most frequent type was squamous cell carcinoma (44%). Lung cancer incidence was lower in patients with worse severity of airflow obstruction. GOLD stages I and II, older age, lower body mass index (BMI) and lung diffusion capacity of carbon monoxide (DLCO)<80% were associated with lung cancer diagnosis.

CONCLUSIONS
Incidence density of lung cancer is high in COPD outpatients and occurs more frequently in older patients with milder airflow obstruction (GOLD stages I and II) and lower BMI. A DLCO<80% is associated with cancer diagnosis. Squamous cell carcinoma is the most frequent histological type. Knowledge of these factors may help direct efforts for early detection of lung cancer and disease management.

CITATION  Am J Respir Crit Care Med. 2011 Oct 15