The wire services are having a field day. Marijuana causes testicular cancer!
Well, you can relax. The results of the study published in the Journal Cancer, (and released online February 9th) is full of caveats, and say it only “appears” that a link “may” exist.
The results and methodology of any research must be looked at closely, and this one is no exception. First of all, an analysis of the research on Medpage , indicates that the study done at the Fred Hutchinson Cancer research center was instituted by a scientist, Janet R. Daling, Ph.D who may very well have set out to prove a link between testicular cancer and cannabis use. While this does not necessarily indicate a bias, it is valuable to note, as studies of this nature often have flaws (and this one is no exception.)
A little about testicular cancer.
First of all, understand that testicular cancer is very rare, amounting to only 1 percent of all cancers in U.S. males. Only about 8000 men are diagnosed with this type of cancer each year, and less than 400 die. It is most common in white males of Scandinavian descent. Other risk factors include: a family history of the disease, abnormal testicular development, or undescended testes.
There are two types of testicular cancer, nonseminoma and seminoma.
It is important to note that the study did not show a direct link, it only suggested a possible one. In addition this potential correlation was only with the nonseminoma variety, which accounts for just 40% of such cancers, or about 3200 annual cases.
A very small study indeed.
The study was based on a very small sampling of 369 men with testicular cancer who filled out a questionnaire. The responses were evaluated based on lifestyle choices, and compared to the answers from a group of 979 cancer-free group with similar backgrounds.
In addition researchers were only able to interview about 250 of men from the first group, and little more than half of the cancer-free control group. Another problem is that the questionnaire relied on self-reported use of marijuana, which, because it is an illicit drug, can skew answers, and finally, there was no central review of the pathology.
So, whether young men facing a diagnosis of cancer are more likely to admit to cannabis use than those not faced with a life threatening disease, cannot be determined from this study. It is also a distinct possibility that other issues such as exercise, diet, tobacco, alcohol and other illicit or prescription drug use were not effectively factored in to the questionnaire.
All in all, the holes in this study make it highly questionable, and in an age where cannabinoid research in the United States has been limited to those studies meant to show harm rather than benefits, we should take these results with a large grain of salt.