Researchers have taken a major step towards developing a
test, which can predict who is predisposed to get prostate cancer, a study
released Wednesday revealed.
In the online edition of the New England Journal of
Medicine, an international research team identified a panel of five genetic
markers, which increase the risk of prostate cancer in Swedish men. The
researchers concluded that men with at least four of the markers were 4.5 times
more likely to develop prostate cancer than men who do not have the markers at
all. Furthermore, those having all five markers and a family history of the
disease were 9.5 times more predisposed to develop the disease. Currently, age,
race and family history are the three risk factors associated with increased
risk of prostate cancer.
The team at Wake Forest University
in North Carolina and Johns
Hopkins University
in Maryland took blood samples from 2,893 men
with prostate cancer and 1,781 men without disease in Sweden.
The discovered 16 small changes in the genetic code that
were more common to men with prostate cancer than those without the disease.
Basing on this discovery, they created a test using the most common of these
changes, called nucleotide polymorphisms or SNPs (pronounced “snips”).
“Our finding provides an opportunity to supplement the
well-established risk factors by looking at how many of these variants a man
has inherited. It may provide a much better weapon to guide clinicians,” Wake Forest’s
Dr. Jianfeng Xu said in a statement.
Doctors currently use a blood test for prostate-specific
antigen or PSA, as well as physical exams to screen for prostate cancer, but
both methods are far from being perfect.
"A subset of men deemed to have a low risk of prostate cancer based on
their PSA levels may in fact be at significantly elevated risk due to
inheriting one or more of the genetic variants," said Dr. Lilly Zheng,
also of Wake Forest, which along with Johns Hopkins
School of Medicine has patented the test.
Xu and his colleagues formed a private company, ProActive Genetics, which
will sell a genetic prostate cancer test for $300 or less this spring, he said.
William B. Isaacs, a professor of urology and oncology at Johns Hopkins and an
author of the new report, said that if the results of the study would be
validated by more study, men might want to get the new genetics test once in
their lifetime, when they are 35.
“The test can provide better information about risk compared
to family history alone. We plan to offer the test now because we believe that
some men and their physicians will want to take advantage of these findings --
knowing that the test will be refined over time,” Xu said.
Some doctors welcomed the initiative with doubt. “If you develop a test and
tell a man you have five times the risk of developing prostate cancer as other
men, what do you do with that?" said Dr. Durado Brooks, director of
prostate and colorectal cancer at the American Cancer Society. He also added
that these genetic variants did not indicate if the disease was aggressive and
needed aggressive treatment or if the disease was a slow-growing cancer that
might not need immediate treatment.
“We still need to fond markers of disease aggressiveness. We still need
better treatments,” he said.
The study also revealed that 90 percent of Swedish men have
at least one of the five telltale genes and prostate cancer death rates tend to
be 10 or 20 percent higher there than among U.S.
whites, according to Henrik Gronberg of the Karolinska Institute in Sweden,
who also worked on the study.
Nearly 220,000 men were diagnosed with the disease in 2007, which
transforms it in the most common malignancy in the U.S. About 27,000 died from it,
according to the American Cancer Society. Prostate cancer was the fifth most
deadly tumor, after lung, breast, colon and pancreatic cancers.