Not all breast cancers are the same. Breast cancers are further described by the stage and grade of the tumor, whether or not lymph nodes are involved, and whether or not the tumor cells are receptive to hormones.
These characteristics are very important because they help to determine what type of therapy your cancer is most likely to respond to, and what type of treatment is best for you. Some can also indicate how likely it is that the cancer will spread to other parts of the body. They are explored through laboratory tests on the tissue removed during a biopsy, with scans on the patient, or both. The results are written in a pathology or radiology report, which is sent to your doctors. You should also request copies for your files.
You may want to get a second opinion on your tumor's characteristics, by asking another pathologist to review the slides made of your tissues.
Types of Cancer
There are several different types of precancerous breast conditions and breast cancers. Sometimes, one sees a mixture of cancer types in a patient's specimen. Most breast tumors arise from cells that line the lobules or the ducts: they are classified according to where they began (lobular or ductal) and whether or not they have grown beyond the site of origin. An in situ tumor is one that is still confined to the site where it began, while an invasive or infiltrating tumor is one that has pushed through the wall of the lobule or duct and is growing into nearby tissues. Some tumors will take years to grow to a detectable size.
Lobular Hyperplasia
Lobular hyperplasia is an overproduction of cells in the lobules of the breast. It is not considered cancerous.
Ductal Hyperplasia
Ductal hyperplasia is an overproduction of cells in the breast duct. It is not considered cancerous.
Lobular Carcinoma in situ (LCIS)
Lobular carcinoma in situ (LCIS) refers to an extensive overproduction of cells in the lobules (more extensive than is found with lobular hyperplasia). The cluster of extra cells has not moved through the walls of the lobule to nearby tissues. LCIS is a condition that alerts the doctor that the patient is at increased risk for eventually developing breast cancer. Women who have this condition are considered at higher risk for eventually developing cancer in either or both breasts.
Ductal Carcinoma in situ (DCIS)
Ductal carcinoma in situ (DCIS) is the earliest stage of breast cancer. DCIS is an overgrowth of cells that began in the breast duct and has not yet moved through the walls of the duct. It is the most common type of non-invasive breast cancer.
Invasive or Infiltrating Ductal Carcinoma (IDC)
Invasive or infiltrating ductal carcinoma (IDC)is a cancerous tumor that began in a duct and has broken through the duct wall to invade other tissues of the breast. It is the most common type of breast cancer, accounting for about 80 percent of all cases.
Invasive or Infiltrating Lobular Carcinoma (ILC)
Invasive or infiltrating lobular carcinoma (ILC) occurs when the abnormal cells break through the walls of the lobule to invade other tissues of the breast. About 10 to 15 percent of all breast cancers are this type.
Inflammatory Breast Cancer
Inflammatory breast cancer may be diagnosed when the cancer cells have spread to the lymphatic channels of the skin. The skin may look red, have the consistency of an orange peel (peau d'orange), or feel warm to the touch.
Other less common types of breast cancer are:
- medullary carcinoma,
- colloid (mucinous) carcinoma,
- tubular carcinoma.
Some other common terms used to describe the status of the cancer are:
- Local spread: a tumor has grown beyond the site of origin and invaded nearby muscles
- Regional spread: cancerous cells have spread to nearby lymph nodes (also called lymph node metastasis), and
- Distant spread or distant metastasis: cancerous cells have traveled to other parts of the body and have begun forming new tumors (called metastases) at those sites. This may also be referred to as metastatic breast cancer.
Stages of Cancer
A tumor's stage is an indication of how far it has spread, both within the breast and to other parts of the body.
Three systems - T, N, and M -- are used to stage a tumor. You may see reference to these three systems on a pathology report. When your doctor discusses it with you, he or she may use a system that combines all three into one, which is described below. T refers to the size of the primary tumor. N refers to whether or not the cancer cells were found in lymph nodes. The term node positive is commonly used to describe tumors that have spread to the lymph nodes, while node negative describes those tumors that have not spread to the lymph nodes. The pathology report may also indicate exactly how many lymph nodes are involved and their sizes. M refers to whether or not the cancer has metastasized, or spread beyond the breast.
When all three systems, T, N, and M, are combined, they are expressed as Stage 0 (defined in table below —DCIS/node negative) through Stage IV. The combination of factors found in each stage is listed below.
| Stage |
Tumor Size |
Lymph nodes |
|
Stage 0 |
DCIS |
Negative |
|
Stage I |
2 cm or less |
Negative |
| Stage IIA |
2 cm or less |
Positive |
| 2-5 cm |
Negative |
| Stage IIB |
5 cm or less |
Positive in the axilla |
| Larger than 5 cm |
Negative |
| Stage IIIA |
Any size |
Positive nodes clumped in the axilla |
| Any size |
Positive nodes in the area under the breastbone (sternum) without positive nodes in the axilla |
| Larger than 5 cm |
Positive in the axilla |
| Stage IIIB |
Any size |
Positive nodes in the area under the breast bone (sternum) with positive nodes in the axilla |
| Any size |
Positive nodes above or below the clavicle |
| Involves the chest wall or the skin of the breast |
Positive or negative |
| Stage IV |
|
Cancer has spread to another organ outside the breast |
Tumor Grade
A tumor's grade is an evaluation of how aggressive or abnormal the cells appear to be when examined under a microscope. It indicates how likely the tumor is to grow quickly and spread to other parts of the body (metastasize). Two different grading scales are used: the nuclear grade and the histologic tumor grade.
The nuclear grade refers to the appearance of the nuclei of the cancer cells. The nucleus of each cell contains the genetic material necessary for the cell to function and grow. A Grade 1 or low grade tumor looks most like normal noncancerous cells and a Grade 3 or high grade tumor looks the most unlike normal cells. Grade 1 tumors are said to be less aggressive, or less likely to grow quickly. Grade 3 tumors are more aggressive, and more likely to grow quickly.
The histologic tumor grade describes how the cells of the tumor look as a structured group. Grade 1 tumors have cells that form glands and look closest to normal, while Grade 3 tumors are more aberrant and disorganized appearing and are likely to be more aggressive in spreading. Grade 1 tumors may also be described as well-differentiated, Grade 2 tumors as moderately-differentiated, and Grade 3 tumors as poorly-differentiated.
In both systems, a lower grade means a less aggressive tumor and a better prognosis.
Characterizing the Cancer
Blood Vessel/Lymphatic Invasion
Sometimes tumor cells will invade the blood vessels or lymph channels within the breast tissue, a condition that can be detected when the pathologist looks at tissue under the microscope. Tumors that exhibit this condition may be more aggressive and more likely to metastasize.
Hormone Receptor Status
On the surface of cancer cells (and normal cells) are numerous receptors, or specialized areas of the cell to which outside substances can bind. Once a substance binds to one of these receptors, it "turns the cell on" in a sense, spurring some sort of action in the cell, such as cell growth and division. Most receptors on cells accept only specific outside substances, much like a lock will accept only a certain key.
Breast cancer cells are described in terms of whether or not they have hormone receptors that accept the hormones estrogen and progesterone. If a cell has such receptors, it is called estrogen receptor positive (ER-positive) or progesterone receptor positive (PR-positive). If these receptors are not present, the cell is said to be estrogen receptor negative (ER-negative) or progesterone receptor negative (PR-negative).
Tumors that are receptor positive are likely to be stimulated to grow by the presence of those hormones. They are also more likely to respond to therapy with hormones or hormone-like substances that can take advantage of that relationship. The drug tamoxifen, for example, acts by blocking a cell's estrogen receptors.
HER-2/neu Oncogene
HER-2/neu is a gene that, when activated, helps tumors to grow by producing a specific growth-stimulating protein. It is found in larger than normal amounts in some breast tumors; those tumors tend to be more aggressive.
A test for the HER-2/neu gene is helpful to determine which women might benefit from the new drug, trastuzumab (Herceptin), which blocks the growth of tumors activated by the gene.
Tests for Metastatic Cancer
The most common sites to which breast cancer spreads are the bones, lungs, pleura, liver, and skin. Less commonly it spreads to the brain, adrenal glands, pericardium, ovary, and leptomeninges. Several tests may be done to determine if a breast tumor has spread.
A chest x-ray may be used to see if cancer has spread to the lungs.
A nuclear bone scan reveals whether cancer is in the bones. In this test, a small amount of a radioactive substance is injected into the bloodstream. The substance then concentrates in abnormal areas of the bone, indicating cancer, arthritis, or a fracture.
A computed tomography scan (CT scan) may be used to see whether the cancer has spread to abdominal structures such as the liver, lymph nodes, or adrenal glands. A CT scan is essentially an x-ray, but rather than taking just one picture of the region, a special x-ray machine rotates around the patient and takes images from many different angles. The images are combined in a computer to create a 3-dimensional picture.
A magnetic resonance image (MRI) uses a very large magnet and radio waves to detect differences in tissues and produce an image of the tissues. Sometimes a dye is injected into the bloodstream to enhance the images. An MRI may be taken to determine if the cancer has spread to internal organs.
A nuclear heart scan (MUGA) may be done to evaluate your heart function before you start treatment. It is not a test for cancer; rather, it is a test to establish baseline heart function before beginning treatment with a drug or drugs that can affect the heart.
Blood tests may also be done to evaluate your organs. A complete blood count (CBC), measures the levels of various types of blood cells. Abnormalities in this test might indicate that the cancer has spread to the bone marrow. A comprehensive panel, which includes liver function tests, helps evaluate liver, bone, and kidney function. Tumor markers, such as CEA, CA15-3, and CA2729, are proteins that may be produced by the cancer cells if they have spread to other organs. They can be detected in the blood, and are used by some doctors to monitor the patient's status.
A PET Scan detects chemical and metabolic activity in tissues, revealing those tissues that are more active than others, such as cancerous tumors. The utility of PET scans in the management of breast cancer patients has yet to be determined, but they may help detect places where the cancer has spread.
