Prostate Cancer Screening

Currently, digital rectal examination (DRE) and prostate specific antigen (PSA) are used for prostate cancer detection. The age at which time screening for prostate cancer should begin is not known with certainty. However, most experts agree that healthy men over the age of 50 should consider prostate cancer screening with a DRE and PSA test. Screening should occur earlier, at age 40, in those who are at a higher risk of prostate cancer such as African-American men or those with a family history of prostate cancer. Men who are concerned about their future risk of prostate cancer should be screened to assess their base-line risk for developing the disease.

Digital rectal exam (DRE): The DRE is performed with the man either bending over, lying on his side or with his knees drawn up to his chest on the examining table. The physician inserts a gloved finger into the rectum and examines the prostate gland, noting any abnormalities in size, contour or consistency. DRE is inexpensive, easy to perform and allows the physician to note other abnormalities such as blood in the stool or rectal masses, which may allow for the early detection of rectal or colon cancer. However, DRE is not the most effective way to detect an early cancer, so it should be combined with a PSA test.

Prostate specific antigen test: The PSA test is usually performed in addition to DRE and increases the likelihood of prostate cancer detection. The test measures the level of PSA, a substance produced only by the prostate, in the bloodstream. The PSA should be less than 1.0 ng/ml The median for men in their 40s is 0.7 ng/ml. If the PSA is higher than the age-specific median, the risk of developing prostate cancer and the risk of having an aggressive form of the disease are increased. Accordingly, the patient might be well advised to have more frequent screening to detect a rise in the PSA level over time.

This blood test can be performed in a clinical laboratory, hospital or physician’s office and requires no special preparation on the part of the patient. Ideally, the test should be taken before a digital rectal examination is performed or any catheterization or instrumentation of the urinary tract. Furthermore, because ejaculation can transiently elevate the PSA level for 24 to 48 hours, men should abstain from sexual activity for two days prior to having a PSA test. A tourniquet or rubber strap is tied around the upper arm to mildly restrict the flow of blood and keep blood in the vein. Then, a needle with a tube-like container attached is inserted into a vein, usually in the bend of the elbow or the top of the hand. After a sufficient sample of blood is obtained, the needle is withdrawn, a bandage is placed on the puncture site and firm pressure is held until the bleeding stops. The entire test takes less than five minutes and produces only mild discomfort. After, the patient may experience slight bruising at the puncture site.

Very little PSA escapes from a healthy prostate into the bloodstream, but certain prostatic conditions can cause larger amounts of PSA to leak into the blood. One possible cause of a high PSA level is benign (non-cancerous) enlargement of the prostate, otherwise known as BPH. Inflammation of the prostate, called prostatitis, is another common cause of PSA elevation, as is recent ejaculation. Prostate cancer is the most serious possible cause of an elevated PSA level. The frequency of PSA testing remains a matter of some debate. The American Urological Association (AUA) encourages men to have annual PSA testing starting at age 50. The AUA also recommends annual PSA testing for men over the age of 40 who are African-American or have a family history of the disease (for example, a father or brother who was diagnosed with prostate cancer), or for those who are interested in an early risk assessment. Some experts have suggested that men with an initial normal DRE and PSA level of less than 2.5 ng/ml can have PSA testing performed every two years. However, a disadvantage of infrequent testing is that it limits the ability to detect a rapidly rising PSA level that can signal aggressive prostate cancer. Recently, several refinements have been made in the PSA blood test in an attempt to determine more accurately who has prostate cancer and who has false-positive PSA elevations caused by other conditions like BPH. These refinements include PSA density, PSA velocity, PSA age-specific reference ranges and use of free-to-total PSA ratios. Such refinements may increase the ability to detect cancer and these should be discussed with your physician.

Currently, it is recommended that both a DRE and PSA test be used for the early detection of prostate cancer. It is important to realize that in most cases an abnormality in either test is not due to cancer but to benign conditions, the most common being BPH or prostatitis. For instance, it has been shown that only 18 to 30 percent of men with serum PSA values between 4 and 10 ng/ml have prostate cancer. This number rises to approximately 42 to 70 percent for those men whose PSA values exceeding 10 ng/ml.

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