[COPD and lung cancer: epidemiological and biological links]

Lung cancer and chronic obstructive lung disease (COPD) are two common fatal diseases. Apart from their common link to tobacco, these two diseases are usually considered to be the result of separate distinct mechanisms. In the past 15 years, numerous studies have produced arguments in favour of a relationship between these two pathologies that goes beyond a simple addition of risk factors. At the epidemiological level, there are data that demonstrate an increased incidence of bronchial carcinoma in patients with COPD. The links between these two pathologies are still unexplained but there are numerous arguments supporting a common physiopathology. Common genetic and epigenetic abnormalities, mechanical factors and signalisation pathways have been quoted. COPD and lung cancer appear to be two diseases possessing a genetic basis that creates a predisposition to environmental or toxic assaults, resulting in a different clinical manifestation in each disease. Consequently, improvements in the management of these two diseases will involve a more intensive investigation of their physiopathology, and require a closer collaboration between research centres and clinical units.