PSA Test Guidelines for Prostate Cancer Inadequate
July 7, 2005
A major study has found that the prostate-specific antigen (PSA) test is a less reliable treatment indicator for prostate cancer than previously believed.
Standard practice maintains that a tissue-sample biopsy was required for further testing only in men with PSA readings >4.0 milligrams per milliliter of blood. However, the new study, published in July 6 issue of the Journal of the American Medical Association (JAMA), revealed no correlation between a specific PSA reading and accurate prediction of prostate cancer.
"It used to be thought of as a dichotomy -- plus or minus, positive or negative. But PSA is now more complex than that," said study leader Dr. Ian M. Thompson, Chairman of the Department of Urology at the University of Texas Health Science Center at San Antonio, as reported by HealthDay News on Tuesday, 5 July. "There is a continuum of risk."
Screening for Prostate Cancer
Screening tests such as the PSA test are judged by their accuracy in two areas: "specificity" - the test's ability to detect a disease, and "sensitivity" - the test's ability to exclude false-positive results.
The JAMA study results showed that existing guidelines for PSA tests are inadequate. In the study, biopsies of men who had a PSA reading of 4.1 detected only 20.5% of existing cancers, while also mistakenly diagnosing cancer (i.e., giving a false positive) in 6.2% of men studied. Moreover, similarly inaccurate readings occurred in men with other PSA levels.
"There is no cutpoint of PSA with simultaneous high sensitivity and high specificity for monitoring healthy men for prostate cancer," concluded the researchers, "but rather a continuum of prostate cancer risk at all values of PSA."
The researchers also pointed out that the study results do not mean that PSA testing has no value, but that it must be taken into consideration along with other important factors, such as a family history of prostate cancer. Moreover, the study results clearly showed that, in men whose PSA levels rose over time, the prostate cancer risk also rose.
"A clear-cut decision rule for prostate biopsy based on PSA value [alone] would be challenging to derive from these data," concluded the researchers. "...There is no single cutoff that would simultaneously yield both high sensitivity and high specificity."
Incidence and Treatment
Prostate cancer is the most commonly diagnosed non-skin cancer in the United States, and one in six American men will develop prostate cancer during his lifetime, according to statistics from the Prostate Cancer Foundation.
The wide variety of available treatments for prostate cancer includes:
- Surgery
- Radiation
- Chemotherapy
- Dietary Changes
- LHRH Agonist Therapy Eligard (leuprolide acetate for injectable suspension), Lupron Depot (leuprolide acetate for depot suspension), Viadur (leuprolide acetate implant) and Zoladex (goserelin acetate implant)
- Androgen Blockers Casodex (bicalutamide), Eulexin (flutamide) and Nilandron (nilutamide)
- Estrogen Therapy DES (diethylstilbestrol), Premarin (conjugated estrogens tablets) and Estradiol (ethinyl estadiol).
More information
To learn more about Prostate Cancer, please click here.
Sources:
Journal of the American Medical Association, Vol. 294, pp.
66-70, 2005.
PSA Testing
for Prostate Cancer Is Tricky, HealthDay News
Pharma Industry News Archive
2007: Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec
2006: Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec
2005: Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec
2004: Jan | Feb | Mar | Apr | May | Jul | Aug | Sep | Oct | Nov | Dec
2003: Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec
2002: Jan | Apr | May | Jun | Aug | Sep | Oct | Nov | Dec
