Recent study from the British Journal of Cancer has found that usage of popular supplements may increase the risk of testicular cancer by up to 300%.
A recent study has found that usage of popular supplements such as creatine and androstenedione may increase the risk of testicular cancer by up to 300%.
While androstenedione is prohibited from use both in and out of competition by the USADA and WADA prohibited lists, it is still an extremely popular, and completely legal, over the counter supplement. Creatine is practically considered an essential supplement for athletes, and is not a prohibited substance.
The study, published in the British Journal of Cancer, consisted of detailed interviews of 869 men - 356 of which had been diagnosed with testicular germ cell cancer, and 513 who had not. The study found that not only was supplement use correlated with a 65% greater risk of testicular cancer, but men who used more than one kind of supplement saw a 177% greater risk, and those who had started using supplements before age 26 had a 121% greater risk.
It should be noted that this increase, while significant, does not make someone as likely to have testicular cancer are the numbers may make it seem. The overall incidence rate for testicular cancer is roughly 5.9 cases per 100,000 men. This means that even a 177% greater risk would result in only around 16.3 cases per 100,000 men. This means your chance of getting testicular cancer, even if the chance was increased by 177%, is still under 1% in your lifetime. By contrast around 1 in 7 men will get prostate cancer in their lifetime.
Of more interest is the fact that the underlying causes of testicular cancer are somewhat poorly understood. The incidence rate of testicular cancer rose from 3.7 cases in every 100,000 men in 1975 to 5.9 cases in every 100,000 men in 2011. Researchers are currently unsure why this is the case. This study points to a potential factor, and further research may be able to isolate specific biological factors which increase or decrease the chances of getting testicular cancer, which could help in prevention efforts in future. More information about the study, and quotes from the study author, can be read here.
Whilst these results are extremely interesting and definitely merit further research, it's important to be aware of the limitations of epidemiological studies, and studies in general, before taking the information provided as fact.
Firstly, while attempts are made to control for factors such as age, race and lifestyle habits, it's impossible for an epidemiological study to fully account for all of these factors. Secondly, while studies such as this have to reach a high bar, a confidence rating of 95% or greater, they are still often incorrect due to something known as publishing bias.
Publishing bias refers to the fact that most null-result studies are unpublished. That is, if a study is performed and the result is that there is no correlation, it is unlikely to be submitted, or accepted, for publication. As a result, even though a confidence rating of 95% means the probability of the results being due to chance is 1 in 20, the number of actual published studies which contain ‘false positives' is significantly higher.
If 1,000 studies are performed, and the chance of any one study having a result which appears due to chance is 1 in 20, that means 50 studies will have an incorrect result due to chance. As a result many studies are unable to have their results replicated, and any study which is original research and has not been replicated or verified, such as this one, should be read as interesting, but far from proven. That being said, there is a growing body of research that some supplements, especially androstenedione and other anabolic agents, have detrimental effects on the testes.
Vox.com had an extremely interesting article on why research studies should be viewed as incomplete information, rather than a factual report, which you can and should read here.
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