30
PROSTATE CANCER: CHAIN OF HORMONAL INTERACTIONS THAT AFFECT THE PROSTATE
30 March 2009
by
admin
Filed under
Men's Health-Erectile Dysfunction
And testosterone brings us to the prostate. Testosterone circulates in the blood and enters the prostate by diffusion, like water through a tea bag. Soon it undergoes a metamorphosis. Testosterone is transformed, by an enzyme called 5-alpha-reductase, into a hormone called DHT(dihydrotestosterone)—which is more than twice as powerful as testosterone. Several studies have shown that the prostate contains less 5-alpha-reductase when it is cancerous; therefore, DHT is not believed to be as important in prostate cancer as it is in the normal prostate or in BPH. Both testosterone and DHT can bind to the same receptor in the prostate cell—like two different keys fitting the same lock. (DHT really binds to it, with great affinity; testosterone does not cling as strongly to the receptor.) When DHT and testosterone hook up to the receptor, it attaches itself to DNA, which then activates certain genes.
Testosterone in the blood circulates back to square one, the hypothalamus, which acts as a thermostat. It measures the level of testosterone and decides whether to boost or cut back on its LHRH production, and the cycle begins all over again (scientists call this a “feedback loop”).
Also, the adrenal glands, which sit on top of the kidneys, make weak male hormones called “adrenal androgens,” including androstenedione, dehydro-epiandrosterone (DHEA), and dehydroepiandrosterone sulfate (DHEAS), plus small amounts of testosterone. These are minor players, believed to make up only 5 percent or less of the total androgen stimulation to the prostate. Their total effect on the prostate is a controversial issue (discussed in this chapter).
So there are several potential checkpoints in this chain of events. Currently, hormone therapy can target the hypothalamus (LHRH), the pituitary (LH, FSH), the adrenal gland (adrenal androgens), the testes (testosterone) and the prostate (DHT). They can be used individually or in combination.
Men on hormonal therapy should go back to their doctor every three to six months for a digital rectal exam, a PSA test, and a creatinine test, which tests for impaired kidney function. They also should get a bone scan once or twice a year if the PSA begins to rise.
*169\201\8*
