Objective: To investigate whether cannabis smoking increases the risk of head and neck cancer.
Design: Case-control study.
Subjects and methods: Cases of head and neck cancer < or =55 years identified from hospital databases and the Cancer Registry, and controls randomly selected from the electoral roll completed interviewer-administered questionnaires. Logistic regression was used to estimate the relative risk of head and neck cancer.
Results: There were 75 cases and 319 controls. An increased risk of cancer was found with increasing tobacco use, alcohol consumption, and decreased income but not increasing cannabis use. The highest tertile of cannabis use (>8.3 joint years) was associated with a nonsignificant increased risk of cancer (relative risk = 1.6, 95% confidence interval, 0.5-5.2) after adjustment for confounding variables.
Conclusions: Cannabis use did not increase the risk of head and neck cancer; however, because of the limited power and duration of use studied, a small or longer-term effect cannot be excluded.