Utility of PSA values questioned
A new study published in the Journal of American Medical Association (JAMA) questions the utility of PSA testing cut off values for the diagnosis of prostate cancer. The study has found that there is not set cut point above which a diagnosis of prostate cancer can be made. It suggests a continuum of prostate cancer risk with increasing levels of PSA. In other words there is no positive PSA test and negative PSA test, and PSA test and age of the patient and the rate of increase in PSA have to be correlated and risk of having prostate cancer is to be assessed.
For the last several years PSA has been a benchmark-screening test to detect prostate cancer. A PSA score of less than four is considered normal, while a PSA above four is considered abnormal and should lead to a biopsy of the prostate. But a study conducted by researchers at the University of Texas Health Science Center at San Antonio challenged the test's effectiveness, reported KPRC-TV in Houston.
Five thousand men were studied over a seven-year period. PSA tests and biopsies were performed on all of the participants. The researchers found that some men with PSA levels as low as one developed prostate cancer, while others with higher PSAs did not. The findings were published in the July 6 issue of the Journal of the American Medical Association.
So is it a worthwhile test?
Dr. Joan Bull, the head of oncology at the University of Texas Health Science Center Houston, said although the test is not perfect, she believes it's needed. "It is worth a lot more than not having it - that we will have better results in the future," she said.
One clear finding that emerged from the study was the increased rate of prostate cancer in men whose PSA levels rose year after year. "If you have a 1.1 and you get your PSA a year later and it is 1.3 and your PSA six months later is 1.4, then one is concerned," Bull said.
Researchers believe the PSA is accurate in detecting high-grade prostate cancers - those more likely to spread to kill a patient. Doctors still belive that PSA is a very useful test.
However, a new way of thinking is needed about a "magic number" that determines whether a patient should get a biopsy or have prostate cancer, according to doctors. What's more important is the dynamics of how that number changes over time and taking into consideration a patient's risk factors.