Relationships between chronic obstructive pulmonary disease and lung cancer: biological insights

Lung cancer (LC) has become one of the leading causes of preventable death in the last few decades (1). Cigarette smoking (CS) stands as the main etiologic factor of LC despite that many other causes such as occupational exposures, air pollution, asbestos, or radiation have also been implicated (1-6). In the 1950s and 1960s, several epidemiologic studies were conducted, in which the links between CS and LC were clearly established (1,7-9). On the other hand, the combination of CS with several environmental or occupational agents may increase the risk of LC in exposed individuals (1). Presently research on the epidemiology of LC is still very active as primary prevention continues to be the most relevant target. Moreover, indoor and outdoor pollutants, which may vary with time, and the components of CS (proportions of tar and nicotine), are also a matter of research nowadays (1). Additionally, the changes in the histopathological characteristics of LC in many developed countries, with a significant rise in the frequency of adenocarcinoma, have also prompted research in this field