Breast Cancer Diagnosis
Accurate diagnosis of breast cancer is derived from gathering information
from a physical exam, biopsy, x-ray scans and lab tests. This information
gathering process is generally referred to as a "workup".
It is important that patients take an active role in understanding
the procedures performed and the results obtained by these procedures.
Ultrasound scanning
This procedure is generally not part of routine screening for breast
cancer, although it can be helpful in determining the difference
between a cyst and a solid tumor. It uses high-frequency sound waves
to image the breast tissue. Other imaging techniques may include
a bone scan. MRI (magnetic reonance imaging), mammography and computed
topography (CT). Mammography and ultrasound are used to more accurately
view what is happening inside the breast itself, while a bone scan,
MRI or CT can reveal if cancer has spread to other areas of the
body.
Fine needle aspiration
A thin needle is inserted into the lump and a sample is withdrawn.
This test helps to determine if the lump is fluid-filled (a cyst,
usually not cancerous) or a solid tumor. It can be performed in
a doctors office with local anesthesia. The sample, regardless if
it is fluid or solid, is sent to the laboratory for further analysis.
Core biopsy
A larger needle is inserted into a lump or an area of abnormality
seen on a mammogram, and a sample of tissue is removed. The sample
is analyzed for cancer cells. This procedure is usually performed
at a hospital with local anesthesia.
Surgical biopsy
The lump and surrounding tissue is removed surgically before being
sent to a laboratory for analysis. This procedure needs to be done
in a hospital with either a local or general anesthetic.
Once a lump is found to be cancerous, further tests are performed
to analyze the tumor itself. The tumor can be examined to find out
how fast it is growing, and what kinds of treatment might work best.
A number of tests are used to help doctors collect information
from the tissue removed during biopsy. These tests help identify
the type of cancer and the best treatment options. The surgical
margins of the tissue are examined for the presence of cancer cells.
If there are no cancer cells at the outer edges of the tissue (clear
margins), there is a good chance all the cancerous tissue was removed
during the biopsy. If cancer cells occur in the margins, more tissue
may need to be removed, and radiation therapy may be used to help
destroy the remaining cancer cells.
The grade (ranging from 1 to 3) of the tumor is also assessed. Grades
1,2 and 3 are referred to as well differentiated, moderately differentiated
and poorly differentiated. Grade 1 cancers tend to grow more slowly
than grade 3. Ploidy is also a characteristic that can be measured
to help predict the aggressiveness of cancer. Diploid cells have
normal amounts of DNA. Aneuploid cells have abnormal amounts of
DNA. Diploid tumors tend to be less aggressive. Most breast cancer
tumors are aneuploid.
S-phase is the stage of cell division where DNA is copied for distribution
to new cells. When testing reveals a high number of cells in the
S-phase, the tissue is growing rapidly, indicating a more aggressive
cancer.
Molecular testing can also provide additional information about
cancer type, and help identify appropriate treatment options. Tests
can be performed to determine if estrogen or progesterone receptors
(proteins on the cell surface that signal it to divide) are present
on the surface of the breast cancer cells. Tumors that are ER or
PR positive typically respond to medications that block hormone
activity: antiestrogen drugs are most common.
Molecular testing will also provide information on breast cancer
HER-2 status. An overabundance of HER-2 on the cell surface, caused
by extra copies of the HER-2 gene inside the cell, is known as HER-2
positive breast cancer. HER-2 positive breast cancer can be more
aggressive than other types of breast cancer; however, a biologic
therapy treatment option is available (see Herceptin®). One
type of test for HER-2 assessment is PathVysion. PathVysion identifies
the number of copies of the HER-2 gene inside the cells. PathVysion
is the only HER-2 testing product available that is FDA approved
for three claims: prognosis; response to cyclophosphamide, doxorubucin
and 5-flourouracil (CAF) chemotherapy, and selection of patients
for whom monoclonal antibody therapy(Herceptin®) is being considered.
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