We've heard the message a million times: the earlier cancer is detected, the better chance you have to beat it.

So when tennis great John McEnroe tells men they should be tested at a younger age for prostate cancer, it seems to make sense. But McEnroe may need to curb his enthusiasm.

September is the first-ever Prostate Cancer Awareness Month, and for good reason. Prostate cancer is the number-one cancer for men in this country. But it's not the number-one cancer killer; lung cancer is.

You see, prostate cancer is a different kind of cancer.

For months now, McEnroe has been urging men to see their doctors and have a prostate test.

"With prostate cancer, if you detect it early, it's almost 100 percent (guaranteed) it's going to be cured," he says in a public service announcement.

McEnroe, who is 50, says men 40 and older should get a PSA test -- the blood test used to detect prostate cancer.

That advice is based on a new recommendation from the American Urological Association, and the recommendation takes 10 years off of those made by other major medical groups.

Ruth Etzioni, a cancer researcher at Fred Hutchinson Cancer Research Center, says it really comes down to balancing the benefits verses the real risks associated with more testing.

"The reason that we start at age 50 is that prostate cancer is a rare condition in men younger than 50. It does occur, but very infrequently," she said.

What would be the downside if all men, 40 to 50 years old, got the PSA test?

"The PSA test is not 100-percent accurate," said Etzioni. "We could be getting many false positive results, unnecessary biopsies and even in the cases that we do detect and treat, it's not clear that detecting them a few years early would be helpful because prostate cancer, in general, is more of a slow-growing cancer."

McEnroe points out that his father had and survived prostate cancer. What he doesn't point out during these interviews is that he's being paid by GlaxoSmithKline, which makes a drug used to treat prostate.

You may be surprised to hear that the American Cancer Society does not support routine testing for prostate cancer because current tests methods are far from reliable.

The American Cancer Society says doctors should talk to patients with "an average risk " for prostate cancer - at age 50 - about yearly testing.

That discussion should take place at age 45 for men at high risk -- African-American men, and men with a father, brother, or son diagnosed with prostate cancer at an early age, or younger than 65.

The same discussion should take place at age 40 for men at even higher risk -- those with several immediate relatives who had prostate cancer at an early age.

For more information:

Can Prostate Cancer Be Found Early?

How is Prostate Cancer Diagnosed?

Consumer Reports: What's Wrong with Free Prostate Screening?

Reuters Health: Prostate Cancer Screening Still Unproven

Prostate Cancer Screening: A Decision Guide