Tests for Prostate Cancer: Effective or Not?

Although prostate cancer is the second leading cause of cancer death in men (lung cancer being number one) it's not clear if the benefits of screening outweigh the risks of treating what is generally a slow-growing and treatable (in the early stages) cancer.

According to the American Cancer Society, there were 217,730 new cases of prostate cancer in 2010, resulting in 32,050 deaths. The prostate--located below the bladder and in front of the rectum--contains cells that make some of the fluid in semen. Prostate-specific antigen (PSA) is an enzyme that keeps the semen in liquid form. In younger men, the prostate gland is about the size of a walnut. However, enlargement can be a normal consequence of aging.

There are two tests to detect prostate cancer-a Digital Rectal Exam (DRE) and a PSA blood test. When performing a DRE, the doctor feels for prostate-gland irregularities through the rectum. PSA levels are analyzed by taking a blood sample. A normal PSA level is less than four nanograms per milliliter (ng/mL); a PSA above ten indicates a high risk of cancer. But there are many exceptions, also called false positives. A high PSA reading could be an indication of some other kind of prostate condition such as enlargement (also known as BPH, benign prostatic hyperplasia) or inflammation (prostatitis).

If detected early, prostate cancer is treatable but recommendations for screening vary due to what some medical experts consider limitations of the PSA screening test.

The PSA Test Controversy

Medicare currently provides coverage for an annual PSA test for all men age 50 and older. The American Urological Association (AUA) recommends a first-time PSA blood test at age 40. Without question, the PSA test helps spot prostate cancer early on but it doesn't tell a doctor if the cancer is dangerous. Only a biopsy can predict an aggressive form of prostate cancer.

Most prostate cancers are slow-growing and may exist for decades before they cause symptoms, which include a weak or interrupted urinary stream; blood in the urine, and impotence. Subsequent PSA tests may indicate a problem before the disease progresses significantly. According to the American Cancer Society, only 25 to 35 percent of men who have a biopsy due to an elevated PSA level actually have prostate cancer-but most do not.

Unnecessary Biopsies: A Cause for Concern

Unnecessary biopsies, undue financial burden, and patient anxiety are among the reasons that compelled researchers from Memorial Sloan-Kettering Cancer Center in New York City to look at data on 5,519 males from the Prostate Cancer Prevention Trial. The patients were all aged 55 years or older and had no previous prostate cancer diagnosis. In addition, all had normal digital rectal exams and a baseline PSA of no more than 3.0 ng/mL. Some of the men were selected to take finasteride, a medication used for patients with BPH, or a placebo for a seven-year period.


After adjusting for age, race (African-American men are prone to prostate cancer) and PSA levels, the scientists found no significant link between rapidly rising PSA levels and biopsy outcomes. It was not the rate of rise that predicted cancer likelihood, but rather the actual PSA level itself. So, a man with a steady PSA level of 5ng/mL was more likely to have prostate cancer than one whose level rose from 2.5 to 3.4ng/mL.

Researchers concluded that PSA velocity (levels that rise rapidly) is a poor predictor of prostate cancer and often leads to unnecessary procedures and worry. According to the Journal of the National Cancer Institute, researchers stated that men should not have a biopsy if their clinical exam is normal.

The UAU guidelines advise a surgical biopsy for men found to have a high PSA velocity even if the doctor finds no other indicators pointing to cancer.

As the debate continues regarding who should get treatment and who should be closely monitored but not treated, studies are ongoing to determine if early tests for prostate cancer in large groups of men will lower the prostate cancer death rate and help men live longer. Until there is more clarity, experts generally agree that it's best to make an informed decision about the potential risks and benefits of PSA screening before being tested.

 


 

Sources:

National Cancer Institute
http://www.cancer.gov

National Institutes of Health
http://www.NIH.gov

American Urological Association Foundation
http://www.Urologyhealth.org