Catching prostate cancer early, when it is most easily and successfully treated, is the rationale behind the sorts of routine screening tests we are given when we visit our physicians.

Early detection begins with a digital rectal examination and a prostate-specific antigen (PSA) blood test, both of which physicians generally recommend annually beginning at age 50 (or, if you are African American or have a family history of prostate cancer, at age 40).

Fingers and needles
During a digital rectal exam, your doctor will insert a gloved, lubricated finger in your rectum to feel for any suspicious lumps on the prostate. While uncomfortable and slightly embarrassing, the exam doesn’t hurt.

However, the physician can only feel the portion of the prostate that sits against the wall of the rectum, which is why the second step is a PSA blood test. PSA is a protein made by the prostate; rising PSA levels can indicate a number of possible prostate problems. Some of these possibilities include:

• Prostate cancer
• An enlarged prostate
• Advanced age
• Use of medications such as Proscar and Propecia

The meaning behind the numbers
PSA levels are not diagnostic: They can't tell you whether or not you have prostate cancer. The only way to diagnose prostate cancer is a biopsy.

Still, the higher your PSA reading, the higher your chance of having prostate cancer. In general, a “normal” PSA reading is anything under 4.0, with cancer risk rising as the number does. A PSA between 4 and 10 translates to a 25% chance of prostate cancer. A PSA over 10 raises that risk to 67%. Some physicians prefer to link PSA level to age.

In addition, keep in mind that one abnormal PSA level doesn't necessarily mean anything; in fact, your doctor may just want to wait and do another test in a few months.

PSA pros and cons
The PSA test may sound like an excellent tool, but controversy dogs the procedure.

First and foremost, just because you have a normal PSA does not mean you are cancer free. Conversely, just because you have an “abnormal” PSA does not mean you have prostate cancer.

Out of those of us who go on to have a prostate biopsy, only 25% to 30% will actually have cancer. Then again, some of us will have PSA results in the normal range, and yet we may still have cancer.

That's why researchers are trying to come up with ways to improve the PSA test. Some of their ideas include:

• PSA velocity, which compares the rate of increase in a PSA score from one year to the next.
• PSA density, which relates PSA levels to prostate size, with larger prostates producing higher PSA levels.
• Free versus attached PSA, which looks at the way in which prostate-specific antigens circulate in the blood. (Attached PSA is more likely to indicate cancer than is free PSA.)

See also

• Prosate cancer - introduction
• Prostate cancer - symptoms
• Prostate cancer - causes and risk factors
• Prostate cancer - diagnosis
• Prostate cancer - treatment options
• Prostate cancer - coping with the aftermath
• Prostate cancer - finding support