This Web site discusses the Prostate Specific Antigen test, or 'PSA.' The PSA is a blood test to help detect prostate cancer. PSA testing is controversial. 

This Web site will give you information to help you and your doctor make a decision about whether a PSA test is right for you.  It is not meant to replace a visit  to your doctor.  The site will take about 10 minutes to read.

 

The prostate is found only in men.  It is about the size of a walnut and located in front of the rectum, behind the penis, and under the bladder.    The prostate produces seminal fluid, which protects and feeds sperm.

After skin cancer, prostate cancer is the most common cancer in men.  Prostate cancer is the second leading cause of cancer-related deaths for men. According to the National Cancer Institute, between 27% and 37% of men between 55 to 74 years of age have prostate cancer.¹ African-American men and men with a family history of prostate cancer have a higher chance of getting prostate cancer.

Prostate cancer is different from many cancers because it often grows very slowly. In 2007, only 27,050 Americans died from prostate cancer, compared to 218,890 men diagnosed with the disease.  Many men with prostate cancer will never know they have it unless they get tested.  In these cases, symptoms or problems are more likely to result from testing and treatment than from the cancer itself. 

All men have PSA inside their prostate and some in their blood.  A value of less than 4 is normal.  Higher values can be caused by prostate cancer.  A high PSA can also be caused by conditions other than cancer like an enlarged prostate, inflammation of the prostate, infection of the prostate, or older age.  Most of the time, an elevated PSA is due to other causes and not due to cancer.  

One use of the PSA test is to screen for prostate cancer.  Screening means to look for cancer early, before any symptoms are present.  If prostate cancer has spread outside the prostate by the time it is diagnosed, treatment is less likely to cure the cancer.  The PSA test may allow doctors to find the cancer early when treatment might work better.  This may prevent the cancer from harming your health.  

To date, it is not certain that detecting prostate cancer early is helpful. As mentioned, the majority of prostate cancers will not cause health problems and therefore do not need treatment.  For cancers that are going to cause health problems, it is unclear whether the problems are made better by beginning treatment early. 

Treatment for prostate cancer can harm your health by causing sexual, urinary and bowel problems.  If the cancer did not need treatment, the side effects of treatment may be worse than having the cancer.  Conversely, if the cancer does do better with treatment, then the harms of treatment may be worthwhile. 

The difficulty is that doctors cannot identify for certain which cancers will spread from those that will never cause health problems.   

There are 4 possible outcomes to a PSA test:

1. Your PSA is normal and you do not have prostate cancer (a true negative).
2. Your PSA is elevated and you do have prostate cancer (a true positive).
3. Your PSA is elevated but you do not have prostate cancer (a false positive).
4. Your PSA is normal but you have prostate cancer (a false negative).

Below is a drawing showing the chance of a true negative, false negative, false positive, or true positive test.  Most positive PSA tests are false positives (about 70%).  Also, there is a chance you may have prostate cancer even with a normal PSA test (about a 1-2% risk).  

If your doctor says that your PSA is positive this does not necessarily mean that you have prostate cancer.  Most causes of an elevated PSA are not due to cancer.  To know if your elevation is from cancer or another cause, your doctor may repeat your PSA test or may recommend a prostate biopsy.  A biopsy is a surgical procedure in which a small sample of prostate is removed for examination under a microscope.  The doctor gets the sample by placing a narrow needle through the wall of the rectum.  The biopsy usually is done in the doctor's office and takes about half an hour. 

In deciding whether or not to get a PSA it may be helpful to think about what you might do if you found out if you had prostate cancer. Three common treatment options are:

1. prostatectomy (surgical removal of the prostate)

2. radiation

   1. external beam radiation
   2. brachytherapy (implanting radioactive seeds in the prostate)

3. watchful waiting

Prostatectomy or radiation try to remove all the cancer cells.  Prostatectomy is surgery to remove the prostate.  Radiation tries to kill the prostate cancer with high dose X-rays.  The X-rays can come from a source outside the body (external beam radiation) or from radioactive seeds placed in the prostate (brachytherapy).   Some research has shown that surgery or radiation may make it less likely for men with prostate cancer to die from prostate cancer within 10 to 20 years.²  Other research has shown that surgery or radiation may not reduce the chances that men with prostate cancer will die from prostate cancer.³  However, it is also known that these treatments can cause problems.  Below are the chances of common problems from two treatment options.   

How many men out of 100 report having these problems.⁴

^{a- Problems with sexual function can include not being able to get an erection, not being able to have intercourse, or being unhappy with the erections you can get.
b- Problems with urination can include having to wear pads because you leak urine, frequent dribbling of urine, or having no control over your bladder.
c- Problems with bowel movements can include frequent bowel movements, sudden urges to have bowel movements, or not being able to control your bowel movements.}

Watchful waiting involves no active treatment. The cancer is monitored with regular PSA tests. While this seems like ‘doing nothing,’ some studies have shown that in the short term (5 to 10 years), men who choose watchful waiting are no more likely to die from prostate cancer than men who choose surgery or radiation.  These men may spare themselves treatment complications. Remember that most prostate cancers grow slowly and may never cause harm.  In these cases treatment may pose a greater risk to health than watchful waiting. 

There are possible advantages to having a PSA test.

1. A normal PSA test may reassure you.
2. A PSA test may find prostate cancer early before it has spread.
3. Treatment of prostate cancer in early stages may help some men to avoid problems from cancer.
4. Treatment of prostate cancer in early stages may help some men live longer.

There are possible disadvantages to having a PSA test.

1. A normal PSA test may miss some prostate cancers.
2. A false positive PSA test may cause unnecessary anxiety. 
3. A false positive PSA test may cause an unneeded prostate biopsy.
4. You may find out that you have prostate cancer, but it may be a cancer that would never cause you any problems.
5. Treatment of prostate cancer may cause you harm.  Difficulties with getting erections or problems with controlling your bladder or bowels are some potential harms.

¹ Cancer Stat Fact Sheets: Cancer of the Prostate. National Cancer Institute, Surveillance Epidemiology and End Results. Available at: http://seer.cancer.gov/statfacts/html/prost.html .
² Wong YN, Mitra N, Hudes G, et al. Survival associated with treatment vs observation of localized prostate cancer in elderly men. JAMA. Dec 13 2006;296(22):2683-2693.
³ Albertsen PC, Hanley JA, Fine J. 20-year outcomes following conservative management of clinically localized prostate cancer. JAMA. May 4 2005;293(17):2095-2101.
⁴ Potosky AL, Davis WW, Hoffman RM, et al. Five-year outcomes after prostatectomy or radiotherapy for prostate cancer: the prostate cancer outcomes study. J Natl Cancer Inst. Sep 15 2004;96(18):1358-1367.

You have been given a lot of information on this web page.  You are encouraged to talk with your doctor, friends, family members, and other men who have had to make the decision whether to get a PSA test.  Make sure that the information you get is correct. 

After understanding the risks and benefits of doing a PSA test, many men decide to have the PSA test, others decide not to do the test.  The final decision is up to you.  Your decision should reflect your personal values and your opinions on the benefits or risks of PSA testing.

Copyright ©
by the
Department of Family Medicine
Virginia Commonwealth University

For questions or comments contact
Alex Krist, MD, MPH
ahkrist@vcu.edu
804-828-9626