PSA - A Numbers Game That Has Changed
This spring a number of medical bodies have made important changes to recommendations about the PSA test. PSA stands for prostate-specific antigen and is a protein found in the blood that comes from prostate tissue. PSA is released from cancerous prostate tissue as well as normal prostate, enlarged, or infected prostate. Because the cancerous tissue releases PSA, it was approved by the FDA in 1986 as a blood test used to monitor progression of cancer in patients known to have prostate cancer. However, in 1994 the FDA approved the PSA blood test in conjunction with a digital rectal exam of the prostate as a diagnostic test for the presence of prostate cancer.
Prostate cancer is the second leading cause of cancer death in men. The incidence of death is 22 per 100,000 from prostate cancer; however, 138 per 100,000 Americans are diagnosed with the disease. There are two messages here: one is that prostate cancer is common (it is the most common cancer in men), but the other is that it does not kill most people who have it. There are two reasons for this: it is a treatable cancer by radiation, surgery and in some cases medicines as well as the cancer in most people is slow growing and not lethal even in those who choose not to have it treated. It is commonly said many more people die with prostate cancer than die from it. In other words, prostate cancer is almost a normal part of aging in males - in fact, 80 percent of men 80 or older will have evidence of prostate cancer at the time of their death.
Risks for Prostate Cancer
There are several risk factors for the development of prostate cancer. The first is age, with a steep increase in cases occurring around age 60. A family history is also an important risk factor. Having a father with prostate cancer significantly increases the likelihood that it will develop in the son, and if there is a sibling with prostate cancer the risk is even higher. African Americans are at greater risk than other races and it occurs at an earlier age in this race. Finally, there is an association with diet: the higher the dietary fat the greater the incidence of prostate cancer.
Back to the PSA and Its Use for Cancer Detection
With the more than 20-year experience using PSA for cancer detection much has been learned and there are some recent clinical trials as well as professional society recommendations out now regarding PSA tests for detection of prostate cancer. It is known that detection of prostate cancer does save lives: 1 out of 1000. That is the evidence to use the PSA to save lives. However, in a number of studies the death from prostate cancer is low and populations who have had PSA have about the same mortality from prostate cancer as those without it. Furthermore, a positive PSA (generally considered a value greater than 4.0) leads to further tests that have risks and to interventions to treat cancer that have significant quality-of-life-altering effects. The major complications of surgery or radiation treatment of prostate cancer are impotence and/or incontinence - both relatively common and serious complications. A newer strategy for prostate cancer is called 'watchful waiting" with semi-annual, annual, or bi-annual physical exams and PSA determinations, withholding radiation or surgery. Some men or their families are not able to accept this approach, preferring to treat the cancer aggressively regardless of the side effects to intervention.
What's a Man To Do?
Most people now agree that PSA is an optional test and if offered it should only be in men ages 55-69 or in selected men with high risk factors. If you are 70, it is not warranted. Because of the harm that comes from the side effects of surgery, most physicians are being advised not to do a routine PSA without a very detailed disclosure of the risks and benefits to the test. More men and their physicians are electing not the measure PSA routinely even in the 55-69 age group. If you have been tested and have a borderline or elevated PSA, a detailed discussion with your physician about the wisdom of watchful waiting is in order. Without the PSA test most men should know that they are going to have prostate cancer before they die, but it is unlikely that it will be what they die from. For an excellent review of the PSA test, please visit cancer.gov. The bottom line is PSA is no longer a required test for men because the life-saving potential is small and the consequences of treatment to quality of life are large. Nevertheless, this is another very personal decision that a person can make with the advice of a physician.
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