Kurt is on the right track. Prostate cancer cells thrive on testosterone, so if you are going to start any kind of t-supplement, make sure that you are not at risk for prostate cancer or have no signs of it. I had the initial signs of prostate cancer and my doctor and I were doing a wait and see what happens treatment since my PSA was higher than normal but not high enough to be concerned. After being diagnosed with leukemia, the immune system went to hell and the prostate cancer grew at a very accelerated and aggressive rate. The leukemia didn't leave me with much of a choice on my treatment options for the prostate cancer, so I had to have the radiation/hormone treatments. The radiation to kill the cancer and the hormones to reduce the testosterone levels that were feeding it.