Cannabis is the most consumed drug in the world and the French are the main consumers in
Europe. The most recognized effects of cannabis on human health are of a neuro-psychic
nature. The medical literature on the effects of cannabis on the lung in general, and on lung
carcinogenesis in particular, is most often reassuring (Tashkin, Chest 2018; Zhang, Int J
Cancer 2015; Ghasemiesfe JAMA Netw. Open. 2019), despite the fact that the concentration of
carcinogens in cannabis smoke is higher than that contained in tobacco smoke (Moir, Chem.
Res. Toxicol. 2008), and that cannabis smoking has been implicated in the occurrence of ENT
cancers. Rather, research focuses on the therapeutic effects of cannabis, especially
analgesics, and even on its possible anti-tumor virtues (Abrams, Jama Oncol. 2020). These
reassuring data should, however, be viewed with a great deal of caution. On the one hand, the
illegal nature of cannabis in most countries and its frequent association with tobacco
consumption make studies on the subject difficult and often biased. On the other hand, the
daily practice of oncologists, who observe numerous cases of advanced and rapidly progressive
lung cancer occurring in young patients who are heavy users of cannabis, raises suspicion of
an unrecognized role of cannabis in lung carcinogenesis.
In a preliminary multicenter study on French patients under 50 years of age operated for
primary lung cancer (Betser, ERJ 2021), we demonstrated that cannabis consumption was
extremely frequent, concerning 43% of patients, but mentioned in patients' medical records
only in 4 out of 10 cases, while the smoking status was always noted.
In addition, by comparing people who smoke cannabis (always here associated with tobacco) to
patients who only smoke tobacco or to non-smokers, we identified a different profile of lung
cancers, with more poorly differentiated tumors, presenting at a more advanced stage (more
T3-T4 versus T1-T2) requiring more complex surgery, and mostly located in the upper lobes of
the lung.
Similar research work is currently underway at Gustave Roussy (Dr Pradere-Dr Planchard,
Villejuif, France) on patients with metastatic lung cancer, with a focus on overall survival
and molecular profile.