Men who use supplements to boost their muscle growth develop testicular cancer 2 to 3 times more often than men who do not use supplements. Researchers at Yale School of Public Health report this in the British Journal of Cancer. The researchers suspect that it’s not substances like creatine, BCAAs and proteins that increase the chance of testicular cancer. They suspect that designer steroids and prohormones are the culprits.
Epidemiologists have suspected since 2005 that there may be a relationship between the use of bodybuilding supplements and testicular cancer. In that year oncologists at Vanderbilt University Medical Center published a small study in which they analysed data from 129 men who had been diagnosed with testicular cancer between 1990 and 2004. [Urology. 2005 Aug;66(2):242-5.] Twenty percent of them had used bodybuilding supplements such as proteins, amino acids, creatine and the prohormone androstenedione in the past.
Twenty percent is a high figure – so the Yale researchers decided to examine the relationship between supplements and testicular cancer more closely. The researchers gathered data from 356 local men, who had been diagnosed as having testicular cancer between 2006 and 2010. They then compared these men with a group of men who did not have testicular cancer.
The men with testicular cancer had used bodybuilding supplements more often than the men who did not have cancer. The table below shows that the use of bodybuilding supplements increased the chance of developing testicular cancer by 65 percent.
The more supplements men use and the longer they use them, the higher the chance. Men who used more than two supplements were three times as likely to develop testicular cancer as those who did not. When epidemiologists encounter such a strong relationship they assume that it should be taken seriously.
The figures in the column Adjusted OR were arrived at by taking into account lifestyle factors such as smoking, alcohol, genetic predisposition and physical exercise. This had little effect. This also suggests that the relationship between bodybuilding supplement use and testicular cancer is real – and that it’s not just a suspected relationship.
The researchers think that it’s not substances like amino acids, proteins and creatine that increase the chance of testicular cancer. They suspect that the prohormones and designer steroids are responsible. They base their arguments, among others, on in-vitro studies in which anabolic steroids such as nandrolone and stanozolol have been shown to increase the chance of testicular cancer. [J Cell Physiol. 2012 May;227(5):2079-88.]
Men who use lots of bodybuilding supplements may also have used more steroids and used them more often, is the researchers’ reasoning. The bodybuilders may have used them consciously or not been aware of what they were doing. Many analyses have shown up small quantities of prohormones and anabolic steroids in bodybuilding supplements. [Scand J Med Sci Sports. 2006 Feb;16(1):41-8.]
“Considering the magnitude of the association and the observed dose–response trends, muscle building supplements use may be an important and potentially modifiable exposure that could have important scientific and clinical importance for preventing testicular germ cell cancer development if this association is confirmed by future studies”, the researchers wrote.
Br J Cancer. 2015 Mar 31;112 Suppl:1247-50.