Cannabis Plus Tobacco Smokers Had More Aggressive Lung Cancers Than Tobacco-Only Smokers

In a prospective study of 150 lung cancer patients aged 60 or under, 39% smoked both cannabis and tobacco (CTSs), 52% smoked only tobacco (TSs), and 9% were nonsmokers. All cannabis smokers also smoked tobacco. Compared to tobacco-only smokers, dual smokers were younger (median 53 vs 56 years), had more rare and aggressive cancers (17% vs 4%, p=0.007), higher emphysema rates (64% vs 38%, p=0.003), and lower gas diffusion capacity (63% vs 70%, p=0.004). Cannabis use was heavy (median 26 years, 4 joints/day).

Multicenter prospective study of 150 consecutive patients aged 60 or under diagnosed with primary lung cancer (2021-2023). Smoking behaviors were self-reported and confirmed by hair testing for nicotine, cotinine, THC, and CBD. Patients were categorized as cannabis+tobacco, tobacco-only, or nonsmokers. Clinical features, tumor characteristics, and surgical outcomes were compared.

This is one of the first prospective studies to use biomarker-confirmed cannabis exposure in lung cancer patients. The finding that dual smokers develop more aggressive tumor types at younger ages is clinically significant, particularly as cannabis use increases globally and most cannabis smokers also use tobacco.

The near-universal co-use of cannabis with tobacco in this population makes it difficult to isolate cannabis's independent effect. However, the significantly higher rates of emphysema and aggressive tumors suggest cannabis smoking adds risk beyond tobacco alone, consistent with the higher temperatures and deeper inhalation patterns of cannabis smoking.

Cannot determine whether cannabis independently caused the worse outcomes since all cannabis users also smoked tobacco. Self-reported use despite hair test confirmation. Relatively small sample (N=150). Single-country study in France where cannabis is typically smoked mixed with tobacco.