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In 1940, the lifetime risk (to age 85) of a woman developing breast cancer in
1940 was 5%, or 1 in 20. Today, nearly 65 years later, the risk is 12.6%, or 1
in 8. In women 40 to 49 years of age, there is a 1 in 66 risk of developing
breast cancer compared with a 1 in 40 risk among women in the 50- to 59-year age
group. While these facts may sound disheartening, innovations in the diagnosis
and treatment of breast cancer offer hope for those affected by this disease.
What are some advances in the diagnosis of breast cancer?
While mammography is still the primary method for diagnosing breast cancer,
technologies such as magnetic resonance imaging (MRI) and positron emission
tomography (PET) scans are finding some cancers missed by mammograms. In
addition, microcrarray technology shows promise for predicting the growth
potential of cancerous tumors.
What is magnetic resonance imaging?
Magnetic resonance imaging (MRI) is a test that produces very clear
pictures, or images, of the human body without the use of X-rays. MRI uses a
large magnet, radio waves and a computer to produce these images.
How is MRI used in diagnosing breast cancer?
MRI may be used to distinguish between benign (non-cancerous) and malignant
lesions, which can reduce the need for breast biopsies. Although MRI can detect
tumors in dense breast tissue, it can’t detect microcalcifications (tiny specs
of calcium), which account for one-half of the cancers detected by mammography.
What is a PET scan?
A positron emission tomography (PET) scan is a unique type of imaging test
that helps doctors see how the organs and tissues inside your body are actually
functioning.
The test involves injecting a very small dose of a radioactive chemical,
called a radiotracer, into the vein of your arm. The tracer travels through the
body and is absorbed by the organs and tissues being studied. Next, you will be
asked to lie down on a flat examination table that is moved into the center of a
PET scanner. This machine detects and records the energy given off by the tracer
substance. With the aid of a computer, this energy is converted into
three-dimensional pictures. A physician can then look at cross-sectional images
of the body organ from any angle in order to detect any functional problems.
How does a PET scan detect breast cancer?
Because of their high rate of metabolism, cancer cells absorb high amounts of
the radioactive tracer. After the tracer is absorbed, PET scans create an image
of the breast, and the scan computes the rate at which the tumor is using the
tracer.
How is a PET scan different from an MRI scan?
One of the main differences between PET scans and other imaging tests like
MRI scans is that the PET scan reveals the cellular level metabolic changes
occurring in an organ or tissue. This is important and unique because disease
processes often begin with functional changes at the cellular level. A PET scan
can often detect these very early changes whereas an MRI detects changes a
little later—as the disease begins to cause changes in the structure of organs
or tissues.
What is microarray technology?
Microarray technology is a way of studying how thousands of genes interact
with each other and how a cell’s regulatory networks control these genes at
one time. The proper expression of genes is vital for maintaining health, as
well as for normal growth and development. Disruptions or changes in gene
expression are responsible for many diseases.
What is "gene expression?"
The term "gene expression" describes the how information contained
within a person’s DNA is copied into messenger RNA molecules. These molecules
are then translated into the proteins that perform critical cell functions.
How does microarray technology assist in diagnosing cancer?
Although this technology is still in its infancy, studies have shown that
microarray technology can be used to measure the activity of many tumor genes
simultaneously. Based on the activity of these genes, the test can predict the
aggressiveness of tumors and also aid physicians in determining which patients
may need follow-up chemotherapy, and which do not.
What are some new treatment options for breast cancer?
Herceptin® (generic name: trastuzumab), is a monoclonal antibody designed
to attack specific cancer cells.
Herceptin targets cancer cells that "overexpress," or make too much
of a protein called HER–2 or erb B2, which is found on the surface of cancer
cells. Herceptin slows or stops the growth of these cells. Herceptin is used
only to treat cancers that overexpress HER–2 protein.
This protein acts as a receptor on the outer walls of cells. When stimulated
by growth factors, an excess of HER-2 receptors can cause the cells to
replicate, divide and grow uncontrollably.
Approximately 25 to 30 percent of breast cancers overexpress HER–2. These
tumors tend to grow faster and are generally more likely to recur than tumors
that do not overproduce HER–2.
How is this drug given?
Herceptin is injected directly into your vein through an IV (intravenously)
and must be administered by a health care provider. For the first treatment, the
dose you receive will be twice the normal dose and will be infused slowly for
about 90 minutes.
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