Hair-Loss Medication Can Affect Prostate Cancer Test

< Dec. 06, 2006 > -- Propecia®, a popular medication used to treat hair loss in men, can change the results of a common test used to screen for prostate cancer, leading to skewed readings that might obscure the presence of disease, a new study finds.

The study was published this week in the medical journal Lancet Oncology, and was funded by Merck & Co., the maker of Propecia.

Propecia can affect the results of a prostate-specific antigen, or PSA, blood test. This test is recommended for men in their 40's and 50's as part of a screening regimen to detect signs of prostate cancer.

Men using Propecia "should be aware that their PSA will be falsely lowered" and that small changes upward could be signs of trouble, says study lead author Dr. Anthony D'Amico, chief of genitourinary radiation oncology at Brigham and Women's Hospital in Boston.

PSA is a substance produced by the prostate gland, which may be found in higher amounts in men who have prostate cancer. The PSA test is usually done annually for men over the age of 50.

Men in high-risk groups, such as African Americans, or those with a strong family history of prostate cancer, should consult their physicians about being tested at a younger age or more often.

Medication Lowers PSA

Propecia's active ingredient, the medication finasteride, was first developed to treat enlarged prostates by targeting an enzyme that plays a role in causing the prostate to grow.

Hair growth was found to be a side effect and finasteride later became a treatment for baldness. About one million American men now take the drug to stave off hair loss.

In a large study released in 2003, the finasteride formulation aimed at treating enlarged prostate, Proscar®, was linked to lowered rates of prostate cancer. According to Dr. D'Amico, doctors have also known for several years that Proscar can change PSA levels in men.

Experts have not known whether Propecia might have similar effects, however, since it contains just one-fifth of the amount of finasteride as Proscar.

In the new study, researchers gave either Propecia or a placebo to 355 men between 40 and 60 years of age with male pattern baldness. Then they studied changes in the men's PSA levels.

The researchers found that within 48 weeks, PSA levels dropped by 40 percent in men aged 40 to 49 who took Propecia and by 50 percent in those aged 50 to 60.

By contrast, PSA levels increased an average of 13 percent in those men who took a placebo.

PSA Test Interpretation Affected

The findings suggest that doctors should adjust their interpretation of PSA tests for men who are taking Propecia long-term, in much the same way they now adjust for Proscar, the study authors say. But the keyword is careful observation.

"You can start by multiplying it [PSA readings] by two, but that is not the [full] answer," Dr. D'Amico says. "You have to look at the level each year. If it goes up three-tenths of a point, you should be talking about a referral for a prostate biopsy."

Why does Propecia disrupt PSA levels in the first place? "By blocking the ability of testosterone to act on the prostate gland, you shut off the enlargement of the gland," Dr. D'Amico says. "If you don't make benign prostate tissue, you don't make the PSA that's associated with it. And that takes PSA levels down."

Always consult your physician for more information.

More About the Prostate

The prostate gland is about the size of a walnut and surrounds the neck of a man’s bladder and urethra - the tube that carries urine from the bladder. It is partly muscular and partly glandular, with ducts opening into the prostatic portion of the urethra. It is made up of three lobes: a center lobe with one lobe on each side.

As part of the male reproductive system, the prostate gland’s primary function is to secrete a slightly alkaline fluid that forms part of the seminal fluid, a fluid that carries sperm. During male climax (orgasm), the muscular glands of the prostate help to propel the prostate fluid, in addition to sperm that was produced in the testicles, into the urethra. The semen then leaves the body out through the tip of the penis during ejaculation.

It is common for the prostate gland to become enlarged as a man ages, and it is likely that a man may encounter some type of prostate problem in his lifetime.

Many clinical problems associated with the prostate gland, which are quite common, and may happen to men of all ages, include prostatism, prostatitis, benign prostatic hyperplasia (BPH), impotence, and urinary incontinence.

Cancer of the prostate is a common and serious health concern. In 2006, according to the American Cancer Society, 234,460 men in the US will be diagnosed with prostate cancer. It is the most common form of cancer of men over age 50, and the third leading cause of death from cancer.

All men are at risk for prostate cancer. The risk increases with age, and family history also increases the risk.

African-American men have about a 60 percent higher incidence rate of prostate cancer than Caucasian men, and nearly a two-fold higher mortality rate than Caucasian men.

The best way for a man to protect himself from prostate cancer is to catch prostate problems early when there is a better chance of successful treatment. Be sure to have prostate screening examinations annually at the appropriate ages.

Always consult your physician for more information.