A study appearing online today in the journal Cancer shows for the first time that marijuana use is associated with an increased risk of testicular cancer. Michael Phelps may not have realized that the repercussions of his public marijuana-smoking episode may go beyond lost endorsement money and disappointed fans.

Researchers at the Fred Hutchinson Cancer Research Center in Seattle interviewed 369 Seattle men aged 18 to 44 who had been diagnosed with testicular cancer and a group of 979 randomly selected age- and geography-matched healthy controls about their history of marijuana use. The results showed that those who reported current use of marijuana showed a 70 percent increase in the risk of testicular cancer. The risk was highest – nearly double – for men who used marijuana at least every week, who started using the drug before the age of 18, or who used it for 10 years or more.

The results also suggested the increased risk appeared to be in the form of testicular cancer called nonseminoma, which is the most aggressive type of testicular cancer and accounts for about 40 percent of cases. Nonseminoma tends to strike early, between the ages of 20 and 35.

The researchers note that this is the first study to examine a relationship between marijuana use and testicular cancer, so more research needs to be done in order to confirm that marijuana use is an important factor in a man's risk of developing testicular cancer.

Experts believe that the foundation of testicular cancer may occur in the womb, when some of the cells that will eventually become sperm fail to develop properly. This leaves them vulnerable to malignancy when they are exposed to high levels of sex hormones during adolescence and early adulthood. This explains why testicular cancer is the most common cancer in males between the ages of 15 and 34.

It may also explain the added risk of marijuana use, since it is known that chronic marijuana exposure has many adverse effects on the endocrine and reproductive systems, including decreased sperm quality, changes in testosterone levels, and male impotency. The male reproductive system also naturally produces a chemical that is similar to the active ingredient in marijuana that is thought to have a protective effect against cancer. The researchers speculate that marijuana use may disrupt this anti-tumor effect, which could explain the link between marijuana use and increased risk of testicular cancer.

Other known risk factors for testicular cancer include a family history of the disease, undescended testes, and abnormal testicular development. It is a relatively rare cancer, with only about 8,000 new cases in the United States each year. According to the National Cancer Society, the five-year survival rate for testicular cancer is around 96 percent.

Experts say that young men should have their testicles examined as part of an annual physical examination and they can also learn how to perform self-examinations to help detect testicular cancer in an earlier stage, when it is easier to treat. For more information, join the Healia Health Community for testicular cancer. If you want to learn more about marijuana abuse, see the Healia Health Community for Drug Problems.

_{Photo: warrentedarrest, Flickr, Creative Commons}