Breast Cancer: Introduction
What is cancer?
Cancer is when cells in the body change and grow out of control. Your body is made
up of tiny building blocks called cells. Normal cells grow when your body needs them,
and die when your body does not need them any longer. Cancer is made up of abnormal
cells that grow even though your body doesn’t need them. In most types of cancer,
the abnormal cells grow to form a lump or mass called a tumor.
Understanding the breast
The breast is made up of lobules and ducts. The lobules are the glands that can make
milk. The ducts are thin tubes that carry the milk from the lobules to the nipple.
The breast is also made of fat, connective tissue, lymph nodes, and blood vessels.
What is breast cancer?
Breast cancer is cancer that starts in the breast. It occurs when cells in the breast
are changed and start to grow out of control. The ducts and the lobules are the two
parts of the breast where cancer is most likely to occur.
Breast cancer is one of the most common types of cancer in women in the U.S. Doctors
don't yet know exactly what causes it. Once breast cancer occurs, cancer cells can
spread to other parts of the body, making it life-threatening. The good news is that
breast cancer is often found early, before it has spread.
Types of breast cancer
There are several types of breast cancer, including these more common types:
Ductal carcinoma. This is the most common type and it begins in the lining of the ducts. When breast
cancer has not spread outside of the ducts, it's called ductal carcinoma in situ (DCIS)
or intraductal carcinoma. This is the most common type of noninvasive breast cancer.
Invasive ductal carcinoma is breast cancer that has spread beyond the walls of the
breast ducts. It's the most common type of invasive breast cancer.
Invasive Lobular carcinoma. This type starts in the milk-producing glands (lobules) and spreads outside the lobules.
Paget disease. This is a rare form of breast cancer that begins in the glands in or under the skin. It
grows slowly and often doesn’t get diagnosed and treated until it is advanced. It
occurs in only one nipple, and causes symptoms that are like a skin infection, such
as inflammation, redness, oozing, crusting, itching, and burning.
Inflammatory breast cancer. This is a rare form of invasive breast cancer. Usually there is no lump or tumor.
Instead, this cancer makes the skin of the breast look red and feel warm. The breast
skin also looks thick and pitted, like an orange peel. In its early stages, inflammatory
breast cancer is often mistaken for a breast infection called mastitis.
Triple negative breast cancer. This is a type of breast cancer that doesn’t have estrogen receptors and progesterone
receptors, and doesn’t have an excess of the HER2 protein on the cancer cell surfaces.
This type of breast cancer tends to occur more often in younger women and in African-American
women. It tends to grow and spread faster than most other types of breast cancer.
The most common kind is invasive ductal carcinoma.
How breast cancer spreads
Breast cancer can spread by growing into nearby tissues in the breast or when the
cancer cells get into and travel through the blood or lymph systems. When this happens,
cancer cells may be found in the lymph nodes in the armpit. These lymph nodes are
called axillary lymph nodes. They are often checked for cancer as part of the diagnosis
process. If the cancer reaches these nodes, it may have spread to other parts of the
Breast cancer that has spread to other organs of the body is called metastatic breast
cancer. When breast cancer spreads to other parts of the body, it most often goes
to the brain, bones, liver, or lungs.
The most important factor in evaluating breast cancer is determining which of these
Noninvasive (in situ) cancer. This occurs only in the ducts or lobules and doesn’t spread to nearby areas. If not
treated, it can later grow into a more serious, invasive type of cancer. If you are
diagnosed with noninvasive carcinoma, your chances of surviving are very high if you
don’t wait to treat it. If you do wait, you’re at risk of the cancer becoming invasive.
Invasive cancer is harder to treat.
Invasive (infiltrating) cancer. This kind of cancer has started to spread to nearby areas. This type is much more
serious than noninvasive cancer. It often invades nearby lymph nodes first. It can
then spread to other parts of your body through your bloodstream and lymphatic system.
Treatment for invasive cancer is usually a more difficult, long-term process.
Talking with your healthcare provider
If you have questions about breast cancer, talk with your healthcare provider. Your
healthcare provider can help you understand more about this cancer.