Seeing gray whiskers in the mirror? You're getting old. You have lots of wrinkles because you worry all the time. And nothing worries guys more than Prostate Cancer.

The prostate has the simple job of secreting about 30% of liquid ejaculate. It is the size of a chestnut, which makes it slightly larger than the male brain. As you age, the spongy gland undergoes hardening and swelling that gradually obstructs the flow of urine, a simple condition that is easily treated with a set of barbaric instruments that would have been the delight of any torturer from the middle ages. But if cancer develops and spreads slowly to bone, you could suffer years of agonizing pain and eventual fatality. One out of six men are diagnosed with prostate cancer during their lifetime, and with a 18% average chance of death, it would seem a no-brainer (even for "Chestnut Brains") to have the prostate removed. However, surgery can cause loss of sexual function and the inability to control your urine. Therapy can include radiation, removal of the testicles, and drugs with nasty side effects that nobody wants to discuss at the dinner table. And those treatments are often limited in effectiveness.

Prostate-Specific Antigen (PSA) is a blood test that can detect prostate cancer -- a seemingly perfect justification for biopsy. So why are some limiting use of the test? Consider this: a dozen needles are poked rectally into this sensitive area to get tissue samples. About 75% of the time the biopsy will be negative, but since the cancer may be small, you are likely to face another biopsy next year if the PSA continues to be high. If cancer is diagnosed, you face even worse choices. Many nervous patients choose aggressive treatment even though progression of prostate cancer is often indolent. The truth is that most men will end up dying of something else, and statistics show that sweating over annual PSA tests does not statistically reduce the likelihood of death.

Should you be tested for PSA? In the context of a strong genetic history and judicious interpretation by a trusted urologist, PSA can be a life saver. But remember -- a little knowledge is a dangerous thing. Particularly if your brain is the size of a chestnut.