WATCH ABOVE: The British Journal of cancer has just published a fascinating study which suggests the possibility that use of muscle-building supplements might increase the risk of testicular cancer. Dr. Samir Gupta discusses the findings.
TORONTO — Can muscle supplements cause testicular cancer?
The British Journal of Cancer has just published a fascinating study by N. Li and colleagues which suggests the possibility that use of muscle-building supplements might increase the risk of testicular cancer. This is particularly interesting because we’ve seen a large increase in testicular cancer rates since the 90s, and we haven’t yet found a clear explanation for this.
In terms of design, this is what’s called a case-control study. The idea is that for a relatively rare event such as cancer, it’s not practical to start with a bunch of men who take supplements and follow them to see how many develop testicular cancer, because it would require too many men and too many years.
So instead, authors started by identifying a bunch of men with a diagnosis of testicular cancer, figured out how many of them had previously taken supplements (at least once a week for at least four consecutive weeks), and then compared this proportion to that in a group of control subjects who did not have testicular cancer. They found that 19 per cent of the men who had testicular cancer had taken supplements, compared to only 12 per cent of the men without cancer. Accordingly, there was a large and statistically significant association between supplement use and testicular cancer.
However, we should note that this kind of study design is not definitive, because there are a number of biases that can creep in. One of the major concerns is “recall bias,” whereby people who have cancer might be much more likely to remember the fact that they once took supplements, because they’re looking for an explanation for their cancer. This might artificially inflate the proportion of people in the cancer group who report having used supplements.
On the other hand, what’s compelling about the study is that the effect size is large, and there seems to be a “dose-response trend,” whereby the younger the men were when they started supplements, and the longer they used them for, the higher the risk of cancer. Also, given that supplement use is increasing and testicular cancer rates are rising, this is an attractive explanation.
The challenge is that this study included 30 different types of powders and pills (any supplement with creatine, protein, and/or the steroid androstenedione), and wasn’t large enough to tell us which exact supplement is the problem, or if it’s an issue across the board. All we know is that supplements containing both creatine and proteins were the most dangerous.
Biologically, the steroid androstenedione is a major concern, as it has been shown to cause testicular damage. People should also be aware of the fact that many “natural” products, and many “non-steroid” supplements have been found to actually contain steroids. In a study published in the International Journal of Sports Medicine in 2004, H. Geyer and colleagues found that 15 per cent of commercially available “non-hormonal” supplements actually contained undeclared hormonal (anabolic) steroids.
TOP 5 – What you need to know about testicular cancer
1. Most common tumor in young men
Overall it accounts for 1 per cent of cancers in men, but it is the most common solid cancer in men between ages 15 – 35.
2. Usually no symptoms
Some men will notice a dull ache, but most men have no symptoms at all.
3. Painless swelling
The key sign for men to be aware of is a hard lump or swelling of a testicle that is painless.
4. Risk factors
A history of an undescended testicle or a family history of testicular cancer are the major risk established factors for testicular cancer.
5. Excellent prognosis
We’ve made huge strides with this cancer in the last 30 years, and the five-year survival rate is now over 95 per cent.
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