New Prostate Test Seeks to Replace Suspect PSA

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Screen Shot 2015-11-10 at 1.07.23 PMThe prostate specific antigen (PSA) test, formerly the gold standard for detecting prostate cancer, has come under much scrutiny in the past few years. So much so, it's now regarded as useless, even harmful, by many urologists. This is because it detects changes in the prostate that may or may not be relevant, and it cannot distinguish between the two broad forms of prostate cancer.

The benign form of the disease is sometimes called "pussycat," and the deadly form, "tiger." The expression "men die with prostate cancer, not from it" refers to the pussycat form, while the opposite is true for tiger. Tiger spreads to the bone, which results in a sure and painful death.

This is the killer, so early detection is key. When the cancer is either slow growing, or removed before it spreads, survival rates are high. But this is not so easy to detect.

There is test called the Gleason score, which is used to determine the likelihood of metastasis. But it involves a biopsy and microscopic examination of the cells.

Scientists at the Karolinska Institute in Stockholm, Sweden may have made a big stride in detection, predicting the presence and type of the cancer, using biomarkers from a blood test. In a new Lancet Oncology paper principal investigator Dr. Henrik Grönberg, Professor of Cancer Epidemiology at Karolinska, describes a very different way to detect and evaluate the cancer.

"PSA can't distinguish between aggressive and benign cancer," Dr. Grönberg explains. "Today, men who don't have cancer, or who have a form of cancer that doesn't need treating, must go through an unnecessary, painful and sometimes dangerous course of treatment. On top of this, PSA misses many aggressive cancers. We therefore decided to develop a more precise test that could potentially replace PSA."

That test (called STHLM3) was performed between 2012 and 2014 on more than 58,000 men between the ages of 50 and 69. They had high Gleason scores (seven or greater), but did not have prostate cancer. All had the PSA test during the study.

STHLM3 involves looking for the presence of protein biomarkers, as well as a marker for a gene variant that is thought to play a part in the disease. Better still, the test was designed to do this by a blood test, rather than using a highly-invasive biopsy.

The results showed real promise, but there is no magic bullet yet. Use of the test reduced the number of biopsies by 30 percent during the study time.

But, more importantly, it detected the aggressive forms of the cancer in men who had low PSA values. These cancers would likely have not been undetected until it is too late. This test will save lives.

This is another example perhaps even the most important of the exploding field of personalized medicine. Data from the American Cancer Society bear this out. In a given year, more than 27,000 men will die from prostate cancer, making it the second leading cause of cancer death in that gender.

With tools to detect and manage prostate cancer that are crude and often inaccurate, this improved test would be an enormous advance.