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More than 200,000 American men will be diagnosed this year with prostate cancer, more than any other cancer. Today in The New England Journal of Medicine, researchers report on a genetic test that shows which men are at high risk.
As NPR's Richard Knox reports, some experts are not sure they can do anything useful with that information.
RICHARD KNOX: Over the past two years, scientists have identified a bunch of genetic markers - distinctive little stretches of DNA that indicate higher risk of prostate cancer. But a man's risk from having just one of these markers isn't much higher, only 10, 20 or 30 percent. The new study looked at the combined effect of a handful of markers on prostate cancer risk among 4700 Swedish men.
Dr. KARIM KADER (Urologist; Assistant Professor, Wake Forest University): We were able to demonstrate by adding five different markers as well as family history. There's a tremendous additive effect to that.
KNOX: That's Dr. Karim Kader of Wake Forest University, a study coauthor. He says men with all five markers plus a family history of prostate cancer have a much higher risk of the disease.
Dr. KADER: They have tenfold the risk of being diagnosed with prostate cancer.
KNOX: That's a meaningful difference. So, the researchers have applied for a patent and are working on a blood test that would tell a man if he's at high risk of prostate cancer.
William Isaacs of Johns Hopkins University thinks it won't take long to develop such a test.
Dr. WILLIAM ISAACS (Urology and Oncology, Johns Hopkins University): One aspect of it may be to identify individuals at risk for the disease at some earlier stage in their life, in their 20s or 30s. So, you may want to screen those men earlier and more intensively. Others, you may be able to wait until later in life before you begin screening for prostate cancer.
KNOX: But there are problems. Karim Kader of Wake Forest says the known genetic markers don't signal what doctors would most like to know about a man's prostate cancer risk.
Dr. KADER: It's not aggressive or less aggressive. They're predictive of your risk of developing prostate cancer, period.
KNOX: Dr. Howard Sandler of the University of Michigan says that's the same problem doctors have with the current screening test for prostate cancer called prostate-specific antigen, or PSA.
Dr. HOWARD M. SANDLER (Radiation Oncology, University of Michigan): We can find lots of prostate cancer with PSA screening. But what's really important is to identify those patients who need to be treated for their prostate cancer.
KNOX: Uncertainty over that question is leading to unnecessary biopsies, surgery and radiation therapy, what the experts call overtreatment
Dr. SANDLER: Overtreatment is common in prostate cancer population because prostate cancer can grow so slowly it might never interfere with someone's life expectancy.
KNOX: I asked Karim Kader, the Wake Forest urologist, if he thinks the new genetic test will increase overtreatment of indolent tumors that may never cause a man any trouble.
Dr. KADER: Oh, most definitely. But I'm not about to bury my head in the sand and disregard early prostate cancer diagnosis just for fear of diagnosing indolent disease.
KNOX: Dr. Edward Gelmann of Columbia University isn't convinced.
Dr. EDWARD GELMANN (Hematology and Oncology, Columbia University): We are a society of the worried well, people want as much information about their health as they can get and they will pay for it. Interpreting it is another matter. You know, if I had a strong family history of prostate cancer, I would be checking my PSA starting at age 50 anyway. If I did these tests and they indicated that my risk was stronger yet, what would I do differently?
KNOX: It's an example of a growing problem. Scientists are getting more information about genetic risk than doctors know what to do with.
Richard Knox, NPR News.