Does Cancer Affect Testosterone Levels in Men?

It's been known for a while that hormone levels drop in women treated for cancer. Now a study published in the Journal of Clinical Oncology is showing similar effects in older men. MSNBC Health reports:

For the new study, researchers tested more than 400 men with cancers that were unrelated to testosterone.
Nearly half the men had total testosterone levels below 300 nanograms per deciliter. The researchers didn't compare the men to a control group, but note that all other studies of men without cancer have found some percentage with lowered testosterone levels, but far less than half.
The men in the current study with low testosterone also tended to be overweight or obese, and scored slightly lower on a scale designed to measure quality of life than men with "normal" testosterone levels.

However, there are some important caveats:

• The study was sponsored by Solvay Pharmaceuticals, which manufactures a testosterone cream. Since the study was essentially designed to identify a target market for their product, that makes the results somewhat suspect. I would like to see the results replicated by another study that's independently funded--and that includes a control group, which this study didn't have.
• Any study examining testosterone levels will be hampered by "a lack of consensus on what constitute a normal range of testosterone levels, the well-known inaccuracy of measuring serum bioavailable testosterone levels, and the considerable interindividual variation in the degree of testosterone decline associated with age," according to this 2006 article in the International Journal of Impotence Research.
• According to that same article, it isn't even clear whether testosterone affects prostate cancer, and if there is a connection, it's that too much testosterone increases the risk of cancer. So when the researchers say that next they're going to see whether testosterone supplementation increases the prognosis for these cancer patients, they're pretty much talking nonsense.

If you're a man who's had cancer, and you're having problems such as impotence that could be related to low testosterone levels, do consult your oncologist and maybe an endocrinologist or urologist--but don't panic.