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Precision Medicine: Biomarker Testing


Welcome to this quick quide
on Biomarker Testing. What is Biomarker Testing? Biomarker testing helps your
doctor understand what is unique about you and your
cancer on a molecular level. It is also called genomic,
molecular, mutation or just tumor marker testing. A biomarker is a molecule in
your body that your doctors can measure to tell
them something specific about you and your cancer. Biomarkers can let doctors
know if your tumor has a good chance of responding
to a certain treatment. Cancer biomarkers can be
proteins or genes (also called DNA). The first step in checking
your cancer biomarkers is for a doctor to collect a sample
from your body and send it to a lab. Your doctor may collect a
sample of your tumor by surgery or biopsy. Samples can also be
collected from your urine, stool, blood, or other bodily
fluids. This process of measuring
biomarkers is called “biomarker testing. How does biomarker testing
help your doctor treat your cancer? Your doctor may be able to
use the results of your biomarker test to match you
with a “targeted” therapy. Targeted therapies are like
puzzle pieces that fit together with their molecular targets
inside your body. This allows the therapy to
stop specific molecules that your cancer needs to grow
and spread. To learn more about targeted
therapies, watch our Precision Medicine: Targeted
Therapy quick guide. For some targeted therapies,
biomarker testing is needed before you can start
the treatment. In these cases, the
biomarker test is called a “companion diagnostic”. For other targeted therapies,
biomarker testing is not required. This is because there are
some biomarkers that are known to always be present
in certain types of cancer. For example, a protein called
BCR-ABL exists in chronic myeloid leukemia (also known as CML) but not in
normal tissue. And a protein called CD30 is
found in most of classical Hodgkin Lymphomas, but is
rarely found in normal tissues. Doctors do not need
biomarker tests to know that CML patients will likely
respond to therapies that target BCR-ABL or that
Hodgkin Lymphoma patients will likely respond to
therapies that target CD-30. Studies have shown that
certain drugs are more likely to work if specific biomarkers
are present. However, it’s important to
know that even when a cancer biomarker is present,
there is no guarantee that the targeted therapy will work
against your cancer. One reason for this is that
the molecular makeup of cancer can change over
time. This means that the target
molecule-or biomarker- can change. The tumor can also find ways
to grow and spread without that molecule. Biomarker testing can be
expensive. Your insurance company
may cover the cost if a targeted therapy is an
option for your type of cancer, and biomarker
testing will help your doctor understand if you are likely to
benefit from that therapy. It is also possible that your
insurance company may not cover the cost of biomarker
testing. You should check with your
insurance company in advance, to find out which
costs will be covered. Some clinical trials will test
your biomarkers at no cost to you. To learn more about clinical
trials, see the Cancer Support
Community clinical trials page at www.CancerSupportCommu
nity.org/ClinicalTrials Other ways that doctors use
biomarker testing in cancer care are: -To make a prediction
about your risk of developing cancer. -To understand the molecular
makeup of your cancer, and how it changes over time. -To judge how likely your
body would respond to treatment. -To look for early signs of
how well your body responds to treatment. -To get a sense of how
quickly your cancer might grow or spread. Biomarker testing alone
cannot be used to diagnose cancer. But it can point to the need
for other tests (such as a biopsy) for this purpose. To learn more, ask your
doctor about biomarker testing and how it can be
used to treat your cancer. Let’s watch a quick scenario
about how this conversation might go. Your job is to help this
patient with acute myeloid leukemia ask her
doctor the best questions about using
biomarker testing. Doctor: That concludes our
exam for today. Did you have any questions
for me? Patient: How can I get a
sample of my cancer tested for biomarkers, to
learn if there are any targeted therapies that might
be right for me? Doctor: If the chemotherapy
regime you are on now works as we hope, that won’t be
necessary. But if there’s a reason to
think about other treatments after that, we can send a
sample of your cancer for biomarker testing then. Patient: Will my insurance
pay for biomarker testing? Doctor: Good question. I
don’t know the answer to that, but I can connect you
with a social worker that would be able to help you
talk to your insurance company and find out. Patient: What would be the
first step, in testing for my cancer biomarkers? Doctor: There’s a blood test
we can do. There’s also a clinical trial
that you might be interested in learning more about. Some clinical trials do this
for free. I’d be happy to give you
some information now, so you can begin learning about
both options. Other questions you could
ask your doctor about biomarker testing are: -Where do I fall on the range
for this biomarker test result? -How close is that to the cut-
off for “positive” versus “negative”? -Are there any other tests
that can measure these same biomarkers? -If I tried one of those other
tests, do you think I might get a different result? -Could the results of my
biomarker test affect my ability to get life insurance? For a list of tumor biomarkers
that are currently in common use, see the Cancer.gov Tumor Markers website in
the Resources section.

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