Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Researcher declares ’PSA era is over’ in predicting prostate cancer risk

13.09.2004


The PSA test, commonly used as a screening tool for detecting prostate cancer, is now all but useless for predicting prostate cancer risk, according to Stanford University School of Medicine researchers. A study of prostate tissues collected over 20 years - from the time it first became standard to remove prostates in response to high PSA levels to the present - reveals that as a screen, the test now indicates nothing more than the size of the prostate gland.



"The PSA era is over in the United States," said Thomas Stamey, MD, professor of urology and lead author of the study published in the October issue of the Journal of Urology. "Our study raises a very serious question of whether a man should even use the PSA test for prostate cancer screening any more."

The PSA test measures prostate specific antigen, a protein normally produced by the prostate gland. Stamey published the original findings in 1987 in the New England Journal of Medicine showing that increased blood PSA levels could be used to indicate prostate cancer. However, through the years, Stamey has come to believe that the PSA test is actually not a useful predictor of the amount or severity of prostate cancer. He said elevated levels of that protein actually reflect a condition called benign prostatic hyperplasia, a harmless increase in prostate size.


Stamey explained the change in correlation over the years by noting that the tumors encountered 20 years ago were generally so large they generated PSA levels high enough to provide a reasonably good measure of cancer severity. Now that screening is more commonplace in this country, many cancers are being caught earlier and are usually smaller - not generating enough PSA to be a good indicator of severity.

Prostate cancer is the most common cancer in men. Stamey cited a 1996 study in which researchers examined the prostates of healthy men who died from trauma, finding that 8 percent of those in their 20s already had prostate cancer. The American Cancer Society estimates that nearly a quarter of a million cases of prostate cancer will be diagnosed in the United States this year alone, and one in six men will be diagnosed with the disease at some point in their lives. Stamey said prostate cancer is a disease "all men get if we live long enough. All you need is an excuse to biopsy the prostate and you are going to find cancer."

However, the risk of dying from prostate cancer is very low compared with lung cancer, which is the leading cause of cancer-related death in men, he said. "Almost every man diagnosed with lung cancer dies of lung cancer, but only 226 out of every 100,000 men over the age of 65 dies of prostate cancer, which is a rate of .003 percent," he said, referring to National Cancer Institute statistics.

Stamey explained the basic dilemma as such: men whose PSA levels are above 2 ng/ml frequently undergo biopsy, which will almost always find cancer, but this does not necessarily mean that prostate removal or radiation treatment is required. "What we didn’t know in the early years is that benign growth of the prostate is the most common cause of a PSA level between 1 and 10 ng/ml," he said.

To figure out the PSA test’s usefulness in determining which cancers warrant radiation or surgery, Stamey and his team from Stanford’s Department of Urology set out to document what was actually found following prostate removal, such as the volume and the grade of the cancer - two indications of the cancer’s severity. They then compared those findings to aspects that could be determined prior to surgery, such as how many of the cancers could be felt by rectal examination and the patient’s blood PSA level.

For the study, they used prostate tissue samples collected by professor John McNeal, MD, who has examined more than 1,300 prostates removed by different urologists at Stanford in the last 20 years. The researchers divided McNeal’s data into four five-year periods between 1983 and 2004 and looked at the characteristics of each cancer. They found that over time, there was a substantial decrease in the correlation between PSA levels and the amount of prostate cancer - from 43 percent predictive ability in the first five-year group down to 2 percent in the most recent one.

However, the Stanford researchers concluded that the PSA test is quite accurate at indicating the size of the prostate gland, meaning that it is a direct measure of benign prostatic hyperplasia. And Stamey pointed out that it is still very useful for monitoring patients following prostate removal as an indicator of residual prostate cancer that has spread to other parts of the body. "Our job now is to stop removing every man’s prostate who has prostate cancer," said Stamey. "We originally thought we were doing the right thing, but we are now figuring out how we went wrong. Some men need prostate treatment but certainly not all of them."

If the PSA test is no longer useful, the question remains as to the best course for detecting prostate cancer. Stamey recommends a yearly digital rectal exam for all men over 50. "If a cancer is felt in the prostate during a rectal examination, it is always a significant cancer and certainly needs treatment," he said.

Unfortunately, he added, even large cancers often cannot be felt during rectal examination. His group is currently working on finding a blood marker that could indicate more aggressive forms of the cancer that can invade the body.

Other researchers who contributed to this work are Mitchell Caldwell, Rosalie Nolley, Marci Hemenez and Joshua Downs. The study was funded by donations to Stamey’s Prostate Cancer Research Fund at Stanford.

M.A. Malone | EurekAlert!
Further information:
http://www.stanford.edu

More articles from Health and Medicine:

nachricht PET imaging tracks Zika virus infection, disease progression in mouse model
20.09.2017 | US Army Medical Research Institute of Infectious Diseases

nachricht 'Exciting' discovery on path to develop new type of vaccine to treat global viruses
18.09.2017 | University of Southampton

All articles from Health and Medicine >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Tiny lasers from a gallery of whispers

New technique promises tunable laser devices

Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...

Im Focus: Ultrafast snapshots of relaxing electrons in solids

Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!

When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...

Im Focus: Quantum Sensors Decipher Magnetic Ordering in a New Semiconducting Material

For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.

Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...

Im Focus: Fast, convenient & standardized: New lab innovation for automated tissue engineering & drug

MBM ScienceBridge GmbH successfully negotiated a license agreement between University Medical Center Göttingen (UMG) and the biotech company Tissue Systems Holding GmbH about commercial use of a multi-well tissue plate for automated and reliable tissue engineering & drug testing.

MBM ScienceBridge GmbH successfully negotiated a license agreement between University Medical Center Göttingen (UMG) and the biotech company Tissue Systems...

Im Focus: Silencing bacteria

HZI researchers pave the way for new agents that render hospital pathogens mute

Pathogenic bacteria are becoming resistant to common antibiotics to an ever increasing degree. One of the most difficult germs is Pseudomonas aeruginosa, a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

“Lasers in Composites Symposium” in Aachen – from Science to Application

19.09.2017 | Event News

I-ESA 2018 – Call for Papers

12.09.2017 | Event News

EMBO at Basel Life, a new conference on current and emerging life science research

06.09.2017 | Event News

 
Latest News

Molecular Force Sensors

20.09.2017 | Life Sciences

Producing electricity during flight

20.09.2017 | Power and Electrical Engineering

Tiny lasers from a gallery of whispers

20.09.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>