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Genetic
Markers Predict
Colon Cancer Survival
NEW
YORK (Reuters Health) - Specific genetic changes that occur in
colon tumors can help doctors predict which patients will benefit
the most from chemotherapy after surgery, new study findings suggest.
While chemotherapy
is often given to these patients in an attempt to wipe out any
cancerous cells that surgery failed to remove, it does not benefit
all patients.
``Identifying
tumors that are not going to be sensitive to chemotherapy...will
allow patients to not waste their time going through courses of
chemotherapy,'' which can have serious and debilitating side effects,
Dr. Stanley R. Hamilton of University of Texas MD Anderson Cancer
Center in Houston, and the study's senior author, told Reuters
Health.
Hamilton and
his colleagues analyzed tumor tissue from 460 patients with colon
cancer who were treated with standard chemotherapy drugs. Their
findings appear in the April 19th issue of The New England Journal
of Medicine.
Patients who
had lost a chunk of chromosome 18 were less likely to survive
five years after surgery compared with other patients. Those with
two other markers--microsatellite instability and a mutation in
a certain gene--were more likely to survive.
Microsatellite
instability (MSI) occurs when a defective DNA repair mechanism
leads to abnormalities in a tumor cell's genetic code.
But further
research is needed to investigate whether these molecular markers
apply to chemotherapy regimens based on newer drugs, such as irinotecan
and oxaliplatin, Hamilton said.
Loss of material
from chromosome 18 occurred in 49% of tumors, high levels of MSI
were found in 21% of tumors, and the gene mutation occurred in
61% of tumors. ``Markers that reliably predict survival are needed,''
the study authors write. ''Our study is a first step toward the
goal of individualized cancer treatment based on the molecular
characteristics of the tumor.''
SOURCE:
The New England Journal of Medicine 2001;344:1196-1206.
Reference
Source 89
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