Blood Test and Cancer
Telomerase
Blood Testing for Lung Cancer
Jo
writes:
"My
husband is having difficulty breathing. He has smoked 3
packs a day, for many years, but quit smoking 8 months ago.
He is spitting up heavy mucus with a light pink tint. He
is seeing a doctor for stomach problems, as well. Although
Kaiser is doing blood tests, the results have come back
normal. Would the blood tests show if there are any cancer
cells present, without the doctor requesting it? Any advice
you can give me would be greatly appreciated."
Dear
Jo:
Blood
is drawn and evaluated to see if the different types of
blood cells are normal in number and appearance, and to
check the levels of certain chemicals and hormones in your
blood. The results show how well your organs are working
and may suggest that cancer is present.
However,
only those blood tests that the doctor orders will be performed
by the laboratory.the doctor must request which blood tests
he wants performed If the blood tests indicate cancer may
be present, a biopsy is usually necessary to make a definite
diagnosis.
Physicians
at the Greenebaum Cancer Center at the University of Maryland
developed a simple blood test that can detect the presence
of telomerase, which may enable the diagnosis of early-stage
lung cancer when it is most curable.
The
team tested 20 lung cancer patients and found that all six
patients who had excess telomerase also had active, advancing
lung disease, while 13 of the 14 who had no detected blood
telomerase activity were in remission.
Cancer
cells often have abnormal telomerase activity. Telomerase
is an enzyme that is responsible for lengthening genetic
sequences called telomeres (telomeres are the specialized
regions on the ends of chromosomes). Telomerase enables
cells to reproduce infinitely.
In
normal cell division (during DNA replication), the telomeres
are shortened (i.e. a portion of the telomere is lost).
When telomeres are shortened to the point that they cannot
form t-loops, the cell remains in an un-dividing state and
eventually dies. This is the natural process that occurs
when disease is not present.
However,
when telomerase is in excess, the normal shortening process
of telomere sequences is restricted (i.e. they never get
to the un-dividing state), which ultimately prevents the
natural process of cell death from occurring. When cellular
death is prevented, the cell continues to divide infinitely.
The result is a malignant (cancer) or benign tumor.
"Our
research shows that when tumors are in remission, telomerase
levels in the blood decline, and when telomerase rises,
the cancer may be growing or spreading," says Austin
Doyle, M.D., University of Maryland Greenebaum Cancer Center
lung cancer specialist and professor of medicine at the
University of Maryland School of Medicine.
Judith
Stamberg, Ph.D., professor of genetics and pathology at
the University of Maryland School of Medicine states, "This
is the first report that telomerase activity in cancer patients
can be detected in blood, and it opens the way for the use
of telomerase as a simple, minimally invasive blood test
for lung cancer.”
Scientists
believe that this blood test is a good screening device
for detecting lung cancer, and could potentially be used
for other cancers, as well. Dr. Stamberg states, “…the blood
test could potentially detect 90 percent to 95 percent of
tumors.” He also points out that since the test will be
inexpensive and easily accessible, thousands of lives could
be saved each year.
Sources:
CancerConsultants.com, University of Maryland Medical Center,
and infoaging.org
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The information on this page has been extracted from http://lungdiseases.about.com/od/lungcancer/
a/telomerase_test.htm.
