Respiratory function and the risk of lung cancer in COPD patients: A population-based cohort study

Abstract

Background: Self-reported smoking status is clear risk factor for lung cancer. However, the degree of airways obstruction may capture additional objective information on smoking history as well as biological susceptibility. Aims and objectives: To examine whether FEV1 measured in COPD patients is an independent risk factor for lung cancer in the UK primary care setting. Methods: A cohort of COPD patients was extracted from a primary care research database containing the anonymised medical records of over 11 million UK residents (The Health Improvement Network). Patients were included if the diagnosis was made between January 1st 1999 and December 31st 2013. The patients were followed from the date of COPD diagnosis to the earliest date of lung cancer diagnosis, death, transferring to a different primary care practice or the last date of data collection. Data were analysed using multilevel Poisson regression. Results: In total 72,538 COPD patients (55% male, mean age 65 years) met the inclusion criteria contributing 359,000 person years (PYs) of data. There were 2,245 new lung cancer diagnoses giving an incidence rate of 62 per 10,000 PYs (95%CI 60-65 per 10,000 PYs). Each 100ml decrease in FEV1 was associated with a 3.5% increase in the incidence on lung cancer (95%CI 2.8-4.4%; p Conclusion: FEV1 recorded in the UK primary care setting is independently associated with the incidence of lung cancer in COPD patients.