'Exciting discovery' in cancer research
Finding suggests virus might cause prostate cancer

SAN FRANCISCO, California  -- In a surprising discovery, researchers
say they have found a virus in some prostate cancer patients, a finding
that opens new research avenues in the most common major cancer among
men in the United States.

The virus, closely related to one previously found only in mice, was
found in cancerous prostates removed from men with a certain genetic
defect. The researchers, with the University of California, San
Francisco and the Cleveland Clinic, warn that they have not discovered
any links between the virus and prostate cancer, but they were
nonetheless excited about prospects for future research.

"It is a very exciting discovery," said Dr. Eric Klein of the Cleveland
Clinic, who will present the findings Friday at an American Society of
Clinical Oncology prostate symposium in San Francisco. "There is now a
suggestion that prostate cancer could be caused by an infectious
disease."

Infectious disease-causing viruses are already blamed for causing some
liver cancers and cervical cancer. That has planted nagging suspicions
in the minds of scientists that some diseases may play important roles
alongside genetics, environment and chance in causing breast, stomach
and several other forms of cancer.

Researchers are not sure how the virus infected people, but suspect it
has been passed on genetically for thousands of years.

"This is a class of virus no one would have looked for in prostate
cancer," said UCSF researcher Joe DeRisi, who developed the so-called
"gene chip" that made the discovery. DeRisi's chip contains 20,000
snippets of vital genetic material from every known virus. It is the
same chip that confirmed a previously undiscovered virus in the cold
family that caused the SARS outbreak three years ago.

After hearing of that success, Klein sent samples of 86 cancerous
prostates he removed from patients to DeRisi. DeRisi then placed DNA
from the cancerous tissues on the chip, and DNA from eight of 20
patients with two copies of a mutated gene matched with DNA from the
mouse virus.

The gene is a vital cog in the body's defense system, coding for an
enzyme that helps kill invading viruses. The men with the mutated genes
make fewer such enzymes than those with normal versions of the gene.

The virus was found in just one of the 66 other patients, suggesting
that genetics play a significant role in the virus' connection to
cancer.

The researchers said they will now test hundreds more prostate patients
and are developing a diagnostic tool to test for the virus in the blood.
That way they could test thousands of patients and non-patients alike
and figure out if there is any link between prostate cancer and the
virus, which causes cancer in mice.

The researchers also want to determine how widespread the virus is in
humans and whether it is exclusive to prostate patients. Prostate cancer
is the most frequent cancer and the second leading cause of death among
men older than 50.

Others are expected to look for other potential viral links to prostate
cancer beyond the well-trod investigative areas of environmental, racial
and genetic backgrounds. Prostate cancer, for instance is found more
often as men age, among blacks and the overweight than in the general
populations. There also are hereditary links to prostate cancer.

Now, researchers have another, potential viral suspect to investigate.

"We haven't really been thinking along those lines," said Dr. Anthony
Zietman, a radiation oncologist at Massachusetts General Hospital. "This
is an interesting finding that will takes off in a whole new direction."