The body is made up of various kinds of cells, which normally divide in an orderly way to produce more cells only when they are needed. Cancer is a group of diseases — more than 100 types — that occur when cells become abnormal and divide without control or order.
When cells divide when new cells are not needed, too much tissue is formed. This mass of extra tissue, called a tumor, can be benign or malignant.
Are not cancer
Can usually be removed
Are rarely a threat to life
Do not come back in most cases
Do not spread to other parts of the body and the cells do not invade other tissues
May be a threat to life
Often can be removed, but sometimes grow back
Can invade and damage nearby tissues and organs
Metastasize. Cancer cells can break away from a malignant tumor and enter the bloodstream or lymphatic system to form tumors in other parts of the body.
There are several types of breast cancer, including:
Ductal carcinoma. This is the most common type and it begins in the lining of the ducts.
Lobular carcinoma. This is another common type and it occurs in the lobules (milk-producing glands).
Paget disease. This is a rare form of breast cancer that begins in the glands in or under the skin. It is often characterized by inflamed, red patches on the skin. Because Paget disease often originates from breast duct cancer, the eczema-like cancer usually appears around the nipple.
Inflammatory breast cancer. This is a rare form of invasive breast cancer. Usually there is no lump or tumor; rather this cancer makes the skin of the breast look red and feel warm. The breast skin also looks thick and pitted, much like an orange peel.
Triple negative breast cancers. These are breast cancers (most often invasive ductal carcinomas) that do not have estrogen receptors and progesterone receptors, and do not have an excess of the HER2 protein on the cancer cell surfaces. These breast cancers tend to occur more often in younger women and in African-American women. They tend to grow and spread faster than most other types of breast cancer.
When breast cancer metastasizes, or spreads outside the breast, cancer cells are often found in the lymph nodes under the arm. If the cancer has reached these nodes, it may mean that cancer cells have spread to other parts of the body.
Cancer that spreads is the same disease and has the same name as the original, or primary cancer. When breast cancer spreads, it is called metastatic breast cancer, even though the secondary tumor is in another organ. This may also be called distant disease.
Types of breast cancer, in alphabetical order, are:
Adenocarcinoma (adenocystic carcinoma)
Ductal carcinoma in situ (DCIS)
Infiltrating (or invasive) ductal carcinoma (IDC)
Infiltrating (or invasive) lobular carcinoma (ILC)
Inflammatory breast cancer
Lobular carcinoma in situ (LCIS) (also called lobular neoplasia)
Paget disease of the nipple
Phyllodes tumor (also spelled phylloides)
Triple-negative breast cancer