Q: My doctor ran a screening PSA on me even though I didn’t have any symptoms and it came back slightly high. What does this mean?
A: Prostate cancer is very common, with about 250,000 new diagnoses in the U.S. each year; one in every eight men is diagnosed with it in their lifetime. Prostate cancer is the third leading cause of cancer death in American men, killing almost 30,000 each year. These are just the diagnosed cases; the disease is actually much more prevalent as shown by autopsy series which identify it in over one third of all men in their 50s and in 75 percent of men over 80. In fact, it may be that every man will eventually develop prostate cancer if he lives long enough.
Prostate specific antigen (PSA) is made by cells of the prostate gland, so a baseline level in the blood is normal. If there is increased production the blood level may be higher, and this is how PSA is used to screen for cancer.
Many things can increase PSA production. Essentially all types of prostate cancer do this, as well as inflammation of the prostate (for example from a bacterial infection), benign prostate enlargement (a non-cancerous condition) and trauma (from a prostate biopsy, a digital rectal exam (DRE) and even from certain exercises such as vigorous bicycle riding). Certain medications can affect the PSA level.
Therefore an elevated PSA does not always mean the patient has prostate cancer. In fact only about 25 percent of patients with an elevated PSA are found to have prostate cancer on biopsy when 4 mg/dl is used as the cut off for normal. In addition, some men with prostate cancer have non-elevated levels of PSA.
The natural course of many (but not all) cases of prostate cancer is indolent, growing very slowly and not causing any problems for many years, so these patients may get little or no benefit from being diagnosed. Furthermore, patients with extremely aggressive cancer may already have widely disseminated disease despite screenings, and once again the benefit from screening may be limited.
Finally, treatment complications can cause death, statistically counteracting the overall population benefit from identifying disease. About one in 200 men undergoing radical prostatectomy and radiation treatment die from complications of their treatments; this number doubles to one in 100 for men over age 75. In addition to this very significant mortality, there is very significant morbidity from many prostate cancer treatments; radical prostatectomy causes sexual dysfunction and/or urine problems in 25 to 50 percent or more of treated men.
Therefore, the overall survival benefit from PSA screening may be limited. In fact, the very large PLCO Cancer Screening Trial failed to demonstrate any decrease in mortality for patients getting PSA screening; although more cancers were discovered in the screening group, this did not translate to an overall survival benefit. This is a “statistical” answer; the individual man who is diagnosed early and successfully treated may have his life saved.
Page 2 of 2 - Ways to improve prostate cancer screening to change the overall risk/benefit analysis are being researched. Unfortunately, adding a DRE to PSA screening or modifying the PSA test itself (for example, looking at changes of the PSA value over time rather than one number, normalizing the PSA level to the size of the prostate, or using newer types of PSA testing such as “free” PSA) has not yet been shown to significantly improve the situation.
Therefore, PSA screening recommendations have become much more reserved. In fact, the United States Preventive Services Task Force and several other authoritative organizations recommend against PSA screening in asymptomatic patients, whereas the American Cancer Society and several other authoritative groups recommend discussing the pluses and minuses with the patient and allowing the patient to make the final decision.
So, if someone has decided to get a PSA screening, what should be done if the value is elevated? The first thing is to wait six weeks and have it repeated, since other causes of elevated PSA (as noted above) may have calmed down in that time. If it is still elevated a biopsy may be recommended, and then treatment options discussed with the patient depending on the biopsy and other disease evaluation results (such as imaging tests to evaluate the extent of the disease).
Note the above discussion is for screening of asymptomatic patients. Patients with symptoms, or use of PSA levels to follow up for recurrent disease after treatment, is a different topic with a different risk/benefit analysis.
Jeff Hersh, Ph.D., M.D., can be reached at DrHersh@juno.com.