Long-term or heavy cannabis use may be associated with a threefold-plus increase in the risk of oral cancer over five years, according to a study published on July 21 in Preventive Medicine Reports.
This correlation persisted after adjusting for factors, including age, smoking, and body mass index (BMI), the authors wrote.
“The observed relationship between CUD (cannabis use disorder) and oral cancer underscores the importance of integrating oral health awareness into substance use disorder treatment and counseling, especially as cannabis use becomes increasingly normalized,” wrote the author, Raphael E. Cuomo, PhD, MPH, of the University of California, San Diego School of Medicine.
This retrospective cohort study analyzed electronic health records from 45,129 adult patients in the University of California Health Data Warehouse. Patients were included if they had a documented drug use screening between January 1, 2012, and December 31, 2019, and no previous oral cancer diagnosis, he wrote.
Participants were followed for five years to track the development of new oral cancers, specifically cancers of the lip or tongue. The main exposure studied was CUD, based on cannabis abuse or dependence. Patients were placed in the CUD group if they received a new CUD diagnosis during the five-year follow-up.
During the follow-up period, 106 patients were diagnosed with oral cancer. The incidence was 0.23% among patients without CUD, aligning with general population rates, while 0.74% of those with CUD developed oral cancer, he wrote.
Unadjusted logistic regression showed that CUD was linked to higher odds of oral cancer (odds ratio [OR] 3.24; 95% confidence interval [CI], 1.5 to 7), and this association remained significant after adjusting for age, sex, BMI, and smoking (adjusted OR 3.25; 95% CI, 1.47 to 7.17).
However, the study had limitations. Its dependence on diagnostic codes may have underestimated both cannabis use and oral cancer cases, Cuomo added.
“As cannabis becomes more widely available and socially accepted, it is critical that public health messaging and clinical guidelines reflect emerging evidence on potential harms,” he concluded.
