Heavy pot smokers are three times more likely to develop oral cancer, a new study finds. Adding cigarettes to the mix ups those odds even more, researchers say.The study included about 45,000 adults who were screened for problematic drug use and followed for five years.Nearly 950 were diagnosed with cannabis use disorder, or CUD… which is defined as the inability to stop using marijuana even when it causes health and social problems.Overall, the results showed participants with CUD had a 325% higher likelihood of developing oral cancer compared to those without the disorder.Participants with CUD who also smoked tobacco were 624% more likely to be diagnosed.Marijuana and cigarettes contain many of the same cancer-causing compounds, according to one researcher who says, "These findings add to a growing body of evidence suggesting that chronic or problematic cannabis use may contribute to cancer risk in tissues exposed to combustion products."The authors say THC, the psychoactive ingredient in marijuana, may also contribute to the increased risk of oral cancer by suppressing the immune system.Approximately 3 in 10 people who use marijuana have cannabis use disorder, according to the CDC.Source: Preventive Medicine ReportsAuthor Affiliation: University of California, San Diego, School of Medicine .Sign up for our weekly HealthDay newsletter