Cancer therapy based on anatomical location may soon be obsolete
- From: J <analyse@invalid>
- Date: Sat, 22 Apr 2006 05:02:16 -0400
This was posted to the prostate cancer newsgroup. i don't get it.
Therapies are supposed to be aimed at result of pathology...
Steph,, what's this saying please. Better pathology testing or testing of
more locations (when mets are present ) or ???
J
http://www.eurekalert.org/pub_releases/2006-04/wuso-ctb041906.php
Public release date: 19-Apr-2006
Contact: [snip]
Washington University School of Medicine
Cancer therapy based on anatomical location may soon be obsolete
The results of a new study at Washington University School of Medicine in
St. Louis could eventually have oncologists removing their specialties
from their shingles by making therapy based on a tumor's anatomical
location obsolete.
When the researchers compared eight different kinds of cancerous tumors,
they saw that whether the tumor was, for instance, a breast tumor, lung
tumor or colon tumor didn't correlate to how the cancers interacted with a
standard anticancer drug.
Their findings suggest that traditional cancer treatments -- which have
established different drug regimens for brain, prostate or ovarian cancer,
for example -- should eventually be replaced with therapies that use drugs
deemed to be of highest benefit based on the tumor's pharmacologic
profile. Treatment choice would be determined by how each patient's tumor
reacts to anticancer drugs, regardless of the tumor's anatomical origin.
"This study is the first time the pathway for a drug's effect has been
analyzed in tumors from different anatomical locations," says Howard
McLeod, Pharm.D., director of the pharmacology core at the Siteman Cancer
Center and a member of the National Institutes of Health (NIH)
Pharmacogenetics Research Network. "We've shown that drug effect is
independent of where the tumor came from in the body. If further studies
confirm that a tumor-specific approach is better than the current
anatomical emphasis, oncologists may have to stop thinking of themselves
as colon cancer or breast cancer specialists and let the cancer tell them
which drugs to use for each specific patient."
The research team analyzed 255 samples of eight different cancers --
colon, breast, prostate, ovary, lung, brain, melanoma and lymphoma -- and
measured the amounts of specific proteins known to influence the effect of
irinotecan, a commonly used anticancer agent. Their study will appear in
an upcoming issue of the Journal of Pathology.
The protein levels that determine irinotecan's effectiveness were found to
be independent of the anatomical origin of the tumor. So, for instance,
the colon tumors studied varied widely in the levels of these proteins.
The same variation in protein levels held true for all of the tumor types
the researchers examined.
"This study provides evidence that the pharmacological pathway of a drug
is important, with significant treatment implications," says Rochelle M.
Long, Ph.D., of the National Institute of General Medical Sciences and
program director for the NIH Pharmacogenetics Research Network. "This work
is in keeping with an overarching Network theme of selecting therapies
tailored for individual patients instead of a one-size-fits-all approach."
The researchers found that, independent of anatomical origin, some tumors
had high amounts of irinotecan's cellular target, a protein labeled TOP1,
while other tumors had very little. Irinotecan would likely be ineffective
in tumors with low TOP1 levels. They also found that tumors varied greatly
in the amounts of proteins that transport irinotecan into and out of their
cells and in the amounts of proteins that break down irinotecan. These
variations determine how well irinotecan will work in a particular tumor.
"Because tumor response can't be predicted from anatomical location, we
should start selecting treatments based on what genes and proteins can
tell us about how the tumor will respond to a drug," says McLeod,
professor of medicine, of genetics, and of molecular biology and
pharmacology. "If we rely just on what has clinically been shown to work
in some cases for a particular anatomically defined cancer, we may not
initially choose the best therapy for the individual patient. And with
advanced cancer, a patient may get only one shot at the right therapy --
making the wrong choice could be deadly."
According to McLeod, under current treatment selection methods virtually
no chemotherapeutic drug has been successful in more than 50 percent of
patients with advanced cancer. But instead of considering a drug that
works only ten percent of the time a failure, he feels it would be better
to consider such a drug effective for one in ten tumors and to search for
the agents among the current arsenal of chemotherapeutic drugs that will
work for the rest.
"We have more than 70 FDA-approved drugs that potentially could be useful
for a particular tumor," McLeod says. "We are now working on methods that
can be used to identify those drugs that will work for each patient's
tumor."
Having a good tumor-drug match not only would improve survival rates, it
would be cost-effective, according to McLeod.
"Since modern cancer therapies can be expensive -- sometimes approaching
the cost of a bone marrow transplant -- the high cost reinforces the
necessity of choosing the right therapy the first time," he says.
Zhang W, Shannon WD, Duncan J, Scheffer GL, Scheper RJ, McLeod HL.
Expression of drug pathway proteins is independent of tumor type. Journal
of Pathology, upcoming issue.
Funding from the National Institutes of Health supported this research.
Washington University School of Medicine's full-time and volunteer faculty
physicians also are the medical staff of Barnes-Jewish and St. Louis
Children's hospitals. The School of Medicine is one of the leading medical
research, teaching and patient care institutions in the nation, currently
ranked fourth in the nation by U.S. News & World Report. Through its
affiliations with Barnes-Jewish and St. Louis Children's hospitals, the
School of Medicine is linked to BJC HealthCare.
Siteman Cancer Center is the only NCI-designated Comprehensive Cancer
Center within a 200-mile radius of St. Louis. Siteman Cancer Center is
composed of the combined cancer research and treatment programs of
Barnes-Jewish Hospital and Washington University School of Medicine.
.
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