[Epidemiological novelties in lung cancer]

Abstract

Lung cancer is the most common cause of cancer-related mortality throughout the world representing around 18% of the total. There is still a male predominance but this is becoming less pronounced and in the US, lung cancer is now the most common cause of cancer-related mortality in women. In France, it had risen to second place in women in 2005 after having been in 6th place in 1975. Median age at diagnosis differs according to countries and health system and is around 70 years in the US and around 65 years in France. The distribution of histological subtypes has changed considerably during recent decades with an increasing frequency of adenocarcinoma at the expense of squamous cell carcinoma. The main risk factor for lung cancer remains active tobacco smoking but the attributable risk of smoking varies from one country to another and according to gender. In Japan, the great majority of lung cancer in women is not attributable to active tobacco smoking. Environmental tobacco smoke exposure has a less important role than active tobacco smoking although it is not negligible. The specific impact of smoking cannabis is difficult to assess precisely as, in most cases, it is mixed with tobacco. However, despite important differences with tobacco smoke, cannabis exposure doubles the risk of developing lung cancer. Occupational risk factors have for a long time been neglected and thus occupational lung cancers have been under-reported. Finally, lung cancer in never-smokers is driving considerable interest as it represents by itself the 7th largest cause of mortality due to cancer. Risk factors involved might be air pollution (indoors and outdoors) but also hormone replacement therapy in women.