Abstract 7394: Investigating the synergistic carcinogenic effect of tobacco and marijuana smoke: A retrospective chart review study Free

Tobacco is the leading preventable cause of lung cancer, and both duration and quantity of tobacco smoking are positively correlated with risk of lung cancer.^1-2 Marijuana has long been speculated to increase the risk of developing lung cancer due to many shared carcinogens with tobacco and its ability to cause cancer cells to grow in vitro.³ While a potential synergistic carcinogenic effect of marijuana and nicotine has been suggested, no clinical studies have yet confirmed this.^4-5

The electronic medical record system was utilized to identify patient age at diagnosis and lung cancer stage at diagnosis in patients with biopsy-confirmed lung cancer in the CHI Health System (Omaha, NE) from January 1, 2017 to December 31, 2022. A total of 156 patients with a history of smoking both tobacco and marijuana concurrently met inclusion criteria. Another 135 patients with a history of smoking tobacco (but not marijuana) were matched as controls according to shared demographic data as well as quantity and duration of tobacco use. One way analysis of variance (ANOVA) and chi-square analysis was used to compare data between groups.

The average age at diagnosis of patients who smoked tobacco and marijuana was 61.3 ± 7.5, compared to 64.0 ± 7.8 for patients who smoked only tobacco (p-value = 0.041). Of patients who smoked tobacco and marijuana, 83 (53%) had stage III or IV lung cancer at time of diagnosis, compared to 75 (56%) patients who smoked only tobacco (p-value > 0.05).

These results suggest that the concurrent use of marijuana and tobacco is associated with a lower age at diagnosis of lung cancer compared to the use of tobacco alone. There was no difference in proportion of patients with advanced stage lung cancer at time of diagnosis between groups. These findings warrant further research into a potential additive carcinogenic effect of smoking tobacco and marijuana concurrently.

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Ryan P. Kimball, Paul J. Wilkinson, Eric C. Lis, Jacqueline W. Poole, Ryan W. Walters. Investigating the synergistic carcinogenic effect of tobacco and marijuana smoke: A retrospective chart review study [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 7394.