Tech & Science

Muscle-Building Supplements ‘Increase Risk of Testicular Cancer’

Weights are seen near the shadow of a man at a gym
REUTERS/Nacho Doce

The increased consumption of muscle-building supplements could explain the rising rate of testicular cancer in young men over the last three decades, according to researchers at Yale University.

In a study published in the British Journal of Cancer, researchers found that men who had taken supplements with the ingredients creatine or androstenedione were more likely to have developed testicular cancer than those that did not.

In the first analytical study to examine the relationship between muscle-building supplements and testicular cancer, researchers based at Yale University in the United States used a sample of 356 men with cases of testicular cancer, and 513 without, as a control group. Answering a wide variety of questions about potential risk factors for testicular cancer, the subjects were also asked whether they took supplements, defined as using them at least once a week for at least four weeks.

According to the authors, almost 20% of those with cases of testicular cancer had used supplements.

“The observed relationship was strong,” said Tongzhang Zheng from Brown University’s School of Public Health, who led the research while at Yale.

He added: “If you used at an earlier age, you had a higher risk. If you used them longer, you had a higher risk. If you used multiple types, you had a higher risk.”

The report says: “The cases were slightly younger and more likely to be white than the controls. The prevalence of cryptorchidism and injury to the testes or groin was higher in cases than that in controls. However, years of education, prevalence of tobacco smoking, prevalence of alcohol drinking, and height were similar in cases and controls.”

Data in the U.S.-based Surveillance Epidemiology and End Results program show that cases of testicular cancer per 100,000 men aged between 15 and 39 increased from 3.7 in 1975 to 5.9 in 2011.

Testicular cancer is the most common form of the disease to affect men between the ages of 15 and 49 according to the NHS, although it accounts for only 1% of cancers in men overall.

The study’s authors conclude: “Considering the magnitude of the association and the observed dose-response trends, muscle-building supplements use may be an important and 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.”