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January 17,
2008
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By Gina Kolata,
New York Times
New DNA test evaluates risk of prostate cancer
A combination of common and minor
variations in five regions of DNA can help predict a man's risk of
getting prostate cancer, researchers reported.
A company, ProActive Genetics,
formed by researchers at Wake Forest University School of Medicine,
expects to offer the test, which will analyze DNA in blood or saliva
samples. It should be available in a few months for less than $300, said
Karen Richardson, a Wake Forest spokeswoman. Read More.
This is, some medical experts say,
a first taste of what is expected to be a revolution in medical
prognostication. The results, they agree, are clear; the question is
what happens next. Because the new test cannot predict which men will
get aggressive cancers, it could lead to more screening and unnecessary
surgery and complications. But, proponents say, it also could help men
decide whether they want more screening in the first place.
The researchers found that about
90 percent of the men in the study had at least one of the gene variants
and that more than half had at least two. The cancer risk increased as
the number of variants rose and increased substantially when men had
four or five of the variants.
Men with four or five variants,
making up 2 percent of the study population, had a risk of prostate
cancer 4 1/2 times that of men who had none of the variants. If the men
also had a family history of prostate cancer, their risk was nearly 10
times as high as that of men with none of those risk factors. Less than
1
percent of
the population had all the variants and a family history.
The researchers report that nearly
half the cases of prostate cancer among the roughly 5,000 men in the
study could be attributed to the five gene regions and a family history.
Prostate cancer becomes more
common as men age; autopsies of elderly men find that most had prostate
cancer, whether they knew it or not. But the men in this study had an
average age of about 65, when the disease is less common and when it has
more time to spread and kill.
William Isaacs, a professor of
urology and oncology at Johns Hopkins University and an author of the
new report, said that if research validates what has been found, men may
want to get the new genetic test when they are young - 35, say. Those at
high risk because of their genetics might then choose to start
prostate-cancer screening earlier than the usual age of about 50, using
a blood test that looks for proteins secreted by prostate tumors.
"I think that makes sense," said
Dr. Howard Sandler, a professor of radiation oncology at the University
of Michigan and a spokesman for the American Society of Clinical
Oncology.
But others worry that more
frequent testing could exacerbate what already is a major problem: side
effects of unnecessary treatment. Most prostate cancers grow so slowly
that they would be harmless if left alone, but because doctors cannot
tell which are dangerous they treat nearly all that they find. Treatment
has serious side effects, including, often, impotence and incontinence.
Nonetheless, researchers say, the test is a harbinger of things to come.
"It's the boutique medicine of the
future," said Dr. Peter Albertsen, a surgery professor and prostate
cancer specialist at the University of Connecticut. "We can know what
diseases we will have to face in the rest of our lives."
That worries him, as it does Dr.
Edward Gelmann, deputy director of the Comprehensive Cancer Center at
Columbia University. "Technology today enables us to find out a huge
amount of information," Gelmann said. "But how does the public deal with
this information? How does it help them make decisions? And if they make
a decision, does that lead to a day, a week, a month, of life saved?"
The study, by scientists at Wake
Forest University School of Medicine, the Karolinska Institute in
Sweden, the Harvard School of Public Health and Johns Hopkins Medical
Institutions, will appear in the Jan. 31 issue of the New England
Journal of Medicine. It has already been released online, a journal
spokeswoman said, because "it
is a very active area of research with a lot of competition." |
