There are some things that are so common that we know about them. Cigarette smoking causes lung cancer.
There are other things that we sometimes do not realize. We have known for years that pipe and cigar smokers are at increased risk for head and neck cancers. We have known for some years that pipe and cigar smokers are at higher risk for bladder cancer.
Head and neck cancers make up about 4 percent of all cancers. There are 71,000 new cases every year. They are associated with about 16,000 deaths per year.
There are other factors that increase the risk of head and neck cancers. They include cigarette smoking. They include alcohol use. Asbestos exposure can do it. Poor oral hygiene is a risk factor. Diets low in fruits and vegetables can also do it. Human papilloma virus and Ebstein-Barr virus infections are risk factors as well.
Now we have a new risk factor to add to the collection. A new study published this month looked at 116,000 patients diagnosed with cannabis use disorder. This disorder occurs in chronic marijuana users.
Symptoms include craving (1) the drug. They include developing tolerance (2) to its effects and having to use more (3) of it. They include using it in high risk situations (4) like driving a car. They include having it cause problems in their everyday life (5) like being unable to maintain a job. They include experiencing withdrawal (6) when it is stopped. They include being unable to quit (7). A diagnosis is made when two of the seven symptoms are met.
Thus the group of 116,000 patients included heavy users of the drug. The average user with the diagnosis smoked about one joint a day for at least two years. Thus the symptoms are brought on by chronic use of small amounts. It is the daily use that leads to the diagnosis not the use of large amounts.
The findings of the study show that these individuals were more likely to develop head and neck cancers than the general population. Thus cannabis use needs to be added to the list of risk factors.
These individuals had 2.5 times the risk of developing oral cancer. They had 5 times the risk of developing cancer of the pharynx. They had 8 times the risk of developing cancer of the larynx.
One of the reasons for this is related to the fact that marijuana users tend to breathe in and hold the smoke in their throat for an extended period. That increases the exposure.
Another reason is that the chemicals (cannabinoids) have cancer producing properties in them.
A third reason is that tetrahydrocannabinol (the substance that produce the marijuana high) seems to accelerate tumor growth once it begins.
These findings should really not come as a surprise. There are so many other risk factors already, that it is logical that something similar to cigarettes, pipe and cigars is just one more to add to the list.