Marijuana Causes Cancer

One of the popular myths about marijuana is that smoking it, when compared to tobacco, does more damage to your lungs and has the potential to cause lung cancer just as tobacco does. Additionally, and related to this topic, it is also commonly believed that marijuana use can lead to emphysema and bronchitis.

Lets begin with the facts. Marijuana does contain both carcinogens and irritants, as does tobacco smoke. However, the majority of marijuana users smoke considerably less marijuana when compared to tobacco users per “smoke break” or session. This reduced usage of marijuana, compared to tobacco significantly reduces the risk of serious lung damage.

On the medical front, there has never been a reported case of lung cancer caused solely by the use of marijuana. Backing this fact up is a 1997 study conducted by the Division of Research, Kaiser Permanent Medical Care Program, Oakland, California, suggesting that marijuana use is not related to cancer incidence.

The purpose of this study was to look at the relationship between marijuana use and cancer. The study was conducted in the cities of San Francisco and Oakland and was populated with 64,855 examinees. All of the examinees in the study had been a part of the Kaiser Permanent multiphase health checkup between 1979 – 1985 and were between the ages of 15 to 49 years old. These examinees completed questionnaires about marijuana and tobacco habits. Follow-ups were conducted through 1993.

The results? The study suggests that for both groups (users & non-users) there is little correlation between marijuana use and an increased risk of cancer in both cities (San Francisco & Oakland).

What does this mean? This means that the study found that there was NO increased risk for cancer in either the non-users or the examinees. Also, there was no association found between marijuana and tobacco related cancers or these other types: lung, cervix, breast, melanoma, colorectal and prostate. However, as stated at the start of this myth about marijuana, both tobacco and marijuana contain carcinogens and irritants.

In addition to the evidence discussed above, a second study conducted in 2006, presented by researcher Donald Tasking, MD at the The American Thoracic Society’s 102nd International Conference suggests that there is no link between even heavy use of marijuana and an increased risk for developing lung cancer.

These studies, as well as others still ongoing, continue to suggest that the common belief that there is a link between marijuana use and an increased risk of cancer seem to be nothing more than another marijuana myth.


I am a medical marijuana patient. I have been blessed with a few different medical conditions including degenerative disk disease, Bertolotti's syndrome, and an extra vertebrae (L6) in my lower back. These medical conditions and/or the severe pain that results, qualify me to be a medical marijuana patient under Washington State law.

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