[Cannabis and lung. What we know and everything we don't know yet]

Cannabis use increased sharply from 2010 to 2014 in France. Cannabis is often consumed with tobacco, although the use of marijuana is developing. Tobacco and cannabis smoke have many common characteristics in terms of irritants, carcinogens and carbon monoxide. They also differentiate by their dependence mechanisms, with nicotine and its receptors for tobacco and tetra-hydro-cannabinol (THC) and its specific receptors for cannabis. Chronic inhalation (700,000 daily users in France) over a long period most likely increases the relative risk of bronchial cancer. But long-term cohort studies targeting this group of strong cannabis users, especially over time, are lacking. Inhalation of cannabis smoke, despite an acute bronchodilator effect, is associated with the risk of chronic bronchitis in the case of regular use. However, the risk of developing COPD in the exclusive marijuana smoker group with no associated tobacco is not yet clear, with studies yielding discordant results. There is also a lack of long-term follow-up studies of respiratory investigations in large cannabis users. Finally, cannabis smoke contains various cannabinoids, for example cannabidiol which also have anti-inflammatory and antifibrotic properties, with the unconfirmed hypothesis that these properties can partially modulate the deleterious action of cannabis smoke.