Two new tests may soon predict prostate cancer risk: body fluids contain valuable biomarkers that could predict cancer risk with up to 90 percent accuracy
Research conducted at the university of Michigan and Wake Forest school of Medicine has produced non-invasive techniques that could predict the likelihood of future prostate cancer with accuracy as high as 90 percent.
URINE TEST AT MICHIGAN. At Michigan, researchers say a simple urine test that detects the presence of four DNA molecules identified 80 percent of patients who later developed prostate cancer. The test was also 61 percent effective in ruling out the disease in other subjects. This means that among those who had fewer than four DNA molecules, six out of 10 would not test positively for prostate cancer. The results of the study were published in the Feb. 1 issue of Cancer Research.
“Relative to what is out there now, this is the best test so far,” says Arul Chinnaiyan, MD, PhD, director of the Michigan Center for Translational Pathology. “We want to develop a test that allows physicians to predict prostate cancer so accurately that a biopsy won’t be needed to rule out cancer.”
Dr. Chinnaiyan believes that any new screening tests for prostate cancer would first be used to supplement the results of the prostate-specific antigen test (PSA). PSA tests are widely used as a screening technique, but the results are not always accurate in predicting future cancer.
BLOOD, SALIVA TEST AT WAKE FOREST. At Wake Forest, a test to identify men at high risk of prostate cancer has been developed based on the results of a study of 4,674 men. The test analyzes DNA in samples of blood or saliva. A research team found that 90 percent of the men (average age 65) had at least one gene variation who participated in the study that, when combined with other gene variations, could predict the future development of prostate cancer. Men with four or five biomarkers had a risk of prostate cancer 4.5 times higher than those with no markers. The risk increased nearly 10 times when a family history of the disease accompanied four to five gene variants. However, less than one percent of the men studied had all of the gene variations plus a family history of the disease.
“This is significant and could affect clinical care,” says Wake Forest senior researcher Jianfeng Xu, MD, DrPH. “The information could substantially improve physicians’ ability to assess risk and determine the need for more aggressive screening or even a biopsy. our finding provides an opportunity to supplement well-established risk factors by looking at how many of the gene variants a man has inherited.”
WHAT THE TESTS MEAN TO MEN. The new test, reported in the Feb. 28 issue of the New England Journal of Medicine, means that men may want to begin testing earlier than the age of 50, which is when men are normally advised to get a PSA test. However, early testing could make the potential side effects of unnecessary treatment (pain, urinary incontinence, impotence following radiation) even worse. Most prostate cancers grow very slowly and some require no treatment at all, but there isn’t a way to differentiate between slow- and fast-growing tumors. Most physicians treat all of them as if they are likely to spread rapidly unless the patient is an older adult. The test will cost $300 and should be available later this year.
THE VIEW FROM DUKE
Andrew J. Armstrong, MD SCM, Assistant Professor of Medicine & surgery, Duke Comprehensive Cancer Center, Departments of Medicine & surgery, Divisions of Medical oncology & urology, DUMC
Reducing Patient-Specific Anxiety
“The goal of prostate cancer screening is to detect potentially fatal disease early so that it may be cured, while sparing the unnecessary harms of further diagnostic tests and treatment of those without fatal disease. These two studies bring us a bit closer to that goal. The Michigan urine biomarker study provides some preliminary evidence for improved accuracy over PSA testing from a relatively small sample of men undergoing biopsy, but the biomarker still suffers from a high false positive and negative rate. This test also does not distinguish fatal from indolent tumors. The Wake Forest study provides evidence that subtle changes in our genetic code may be evaluated in a blood or saliva test to select men for more aggressive screening programs. However, this study was also not able to distinguish fatal from indolent tumors, illustrating the need for more research. These two studies may eventually reduce the number of unnecessary biopsies in men undergoing PSA screening, but this remains to be demonstrated.”
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