The most widely used staging system is the TNM classification. TNM stands for Tumor,
Nodes, and Metastasis. TNM takes into account the size of the tumor, the number of cancer
nodes and whether the cancer has spread to other areas of the body, or metastasized.
The stages of breast cancer can range from zero to four, and depend on the combination
of TNM categories. For example, a cancer with a T1 tumor, a tunor that is less than 2cm,
has no cancerous nodes, designated N0, and no distant metastasis designated M0, is classified
as Stage 1.
In general, the higher the stage of the cancer, the worse the chances are for survival. The
highest stage, Stage 4, is any cancer with distant metastasis, designated M1, regardless
of the size of the tumor or status of the lymph nodes.
Now let's go back to the other prognostic factors that are important.
By looking under a microscope at the biopsy tissue, the pathologist determines how closely
the cancer cells resemble normal tissue.
Although lymph node status is still the most important predictive factor, tumor grade is
helpful in further differentiating tumors of the same stage.
There are a number of different types of breast cancer. The type of breast cancer that you
have can affect your choice of treatment.
The most important distinction is between in situ and invasive breast cancer.
In situ means in place. These cancers are contained in milk ducts and lobules of the
breast and have not spread to surrounding breast tissue, as happens with invasive breast
cancer.
Invasive cancers have a worse prognosis than in situ cancers because once the cancer has
spread to surrounding breast tissue it can spread to lymph nodes and other parts of the
body.
The pathologist determines whether a cancer is invasive or in situ.
Ductal Carcinoma In Situ, or DCIS, occurs when cells originate in milk ducts.
Lobular Cancer In Situ occurs when cells originate in the lobules of the breast.
These are precancerous conditions and the prognosis is excellent.
There are numerous types of invasive cancer.
The pathologist looks at the characteristics of the breast cancer cells and classifies
the cancer into a particular type. 70% of breast cancer is infiltrating ductal. The
next most common type is infiltrating lobular. It has a prognosis similar to infiltrating
ductal cancer. Those with the best prognosis include mucinous, or colloid carcinoma, tubular
carcinoma, and medullary and papillary carcinoma.
Another prognostic factor is the presence or absence of estrogen and progresterone receptors
on the tumor.
The body produces estrogen and progesterone, and some breast cancers have receptors that
bind these hormones. The presence of estrogen or progesterone receptors
in the tumor will determine if your tumor will respond to hormonal treatment, as well
as how the treatment will affect your prognosis.
Tumors that have many sites to which estrogen and progesterone attach are known as hormone
receptor positive tumors.
This is determined by a special stain done on the tumor cells by the pathologist.
A receptor positive tumor often needs hormones to grow. Blocking hormones from the tumor
slows its growth. The drugs most often used are tamoxifen or an aromatase inhibitor.
In women who are estrogen and progesterone receptor negative, these drugs are not effective
because the cancer does not need hormones to grow.
Hormone receptor positive tumors have less chance of a recurrence than hormone negative
tumors.
How fast a tumor is growing is known as its proliferation rate. Tumors that are fast growing
are more likely to spread to other parts of the body. There are two common tests that
are used to determine the proliferation rate.
When cells are dividing, or proliferating, they express a protein in their nuclei called
a proliferation antigen. By counting the number of cells expressing this antigen, a tumor's
proliferation rate can be determined. Cells expressing the proliferation antigen can be
identified using the Ki-67 antibody, which attaches itself to the antigen. If the Ki67
antibody attaches to numerous cells in a tissue sample, the tumor cells are probably going
to divide rapidly.
Sphase Function is less reliable than the use of the Ki-67 antibody. The Sphase is the
point of cell division where DNA is reproduced just before the cell splits in two. A tumor
with many cells in Sphase can indicate a fast growing tumor.
Her-2/Neu is a protein that appears in high numbers on the outside of the breast cancer
cells of some patients. High levels of Her-2/Neu may be associated with a higher risk of breast
cancer recurrence.
The most accurate test for Her-2/Neu overexpression is the FISH test (Fluorescent in situ Hybridisation).
Breast cancer cells that are Her-2/Neu positive do not respond as well to certain chemotherapy
drugs. However, the good news is that breast cancer cells that are Her-2/Neu postive respond
to Herceptin.
Herceptin is an antibody that attaches to the Her-2/Neu protein on the surface of the
cancer cell slowing its growth.
The major side effect of Herceptin is congestive heart failure in 3-4% of women. Your heart
function will be followed carefully if you receive Herceptin.
After you've had your surgery, you will meet with your doctor to discuss the pathologist’s
report. You will find out the type of breast cancer, its size and grade, and type of growth.
You will also discuss whether the nodes are involved, the stage of the disease, the hormone
receptor and Her-2/Neu status.
It is important that you understand what these factors are. You may want to bring a friend
to the meeting and tape record the discussion so you can go over it later.
Depending on the stage of your cancer, your physician may want to get additional tests
such as a bone scan, CT scan, and PET scan of your body to see if your cancer has spread.
A bone scan is a test where tiny amounts of a radioactive substance are injected into
the vein. Two to three house later, the entire body is scanned. Areas that are intensely
black indicate where cancer is growing in the bones.
CT scans create an image of internal organs of the body. They are not capable of showing
very small areas of tumor involvement.
PET scanning is becoming increasingly popular for staging breast cancer. It involves injecting
a radionuclide combined with a sugar into a vein. Because malignant tumors are growing
at such a fast rate compared to healthy tissue, the tumor cells will use up more of the sugar
which has the radionuclide attached to it. The computer measures the amount of glucose
consumed by the cancer cells to produce a color-coded picture. These tests may be negative
but that does not mean there's no cancer present.
These factors are used by your physician to determine your chances of being cured and
whether these chances can be improved by the use of chemotherapy or hormonal therapy, or
both, referred to as adjunctive systemic therapy.
As mentioned earlier, the goal of systemic treatment in early stage breast cancer is
to eliminate any cancer cells, called micro metastases, that may have spread from the
breast tissue to other parts of the body. It is called systemic treatment because the
entire system of the body is treated.