In breast cancer, some cells begin growing abnormally. The cells divide more rapidly than healthy cells and may spread through the breast tissue to the lymph nodes or other parts of the body (metastasize). The most common type of breast cancer begins in the milk-producing ducts, but cancer may also occur in the lobules or in other breast tissue.
According to the National Cancer Institute (NCI), breast cancer is the second leading cause of cancer death in American women.
In the United States, it is estimated that 12% of American women will develop the disease and 3.5% will die from it.
The incidence of breast cancer varies with age being very low in the twenties, gradually increasing and reaching a plateau at the age of 45 and then increasing dramatically after fifty. Breast cancer is diagnosed in women over 65 years 50% of the time, indicating the ongoing necessity for women to have yearly screenings.
Although rare, breast cancer may also occur in men. In men, breast cancer can occur at any age, but is most common between the ages of 60 to 70 years. For every 100 cases of breast cancer, less than 1 is found in men.
Breast cancer is considered a heterogeneous disease, meaning that it is a different disease in different women, a different disease in different age groups and has different cell populations within the tumor itself. Generally, breast cancer is a much more aggressive disease in younger women.
There are many different varieties of breast cancer. Some cancer cells are fast growing while others are slow. Some cancer cells are stimulated by the estrogen in the body while others result from an out-of-control oncogene (cancer gene). Treatment is based on the special characteristics of the breast cancer.
Stage 0: Stage 0 is when the cancer has not spread from the breast tissue. Stage 0 may also be known as noninvasive carcinoma or carcinoma in situ. Lobular carcinoma in situ (LCIS) refers to abnormal cells in the lining of a lobule that seldom become invasive cancer. Their presence is a sign that a woman has an increased risk of developing breast cancer, and this risk of cancer is relevant for both breasts.
(DCIS): DCIS refers to abnormal cells in the lining of a duct. DCIS is also called intraductal carcinoma. The abnormal cells have not spread beyond the duct invading the surrounding breast tissue, but women with DCIS remain at an increased risk for invasive breast cancer. The most common type of breast cancer is ductal carcinoma. Both DCIS and LCIS are classified as Stage 0.
Stage I and II: Stage I and stage II are early stages of breast cancer in which the cancer has spread beyond the lobe or duct invading nearby tissue. Stage I means that the tumor is no more than one inch across, and has not spread beyond the breast. Stage II means that the tumor in the breast is less than 1 inch across and the cancer has spread to the lymph nodes under the arm, that the tumor is between 1 and 2 inches across with or without infiltration to lymph nodes under the arm (called Stage IIa), or that the tumor is larger than 2 inches across, but has not spread to the lymph nodes under the arm (called Stage IIb).
Stage III: Stage III is also known as locally advanced cancer. In this stage, the tumor in the breast is smaller or larger than 2 inches and has spread to the lymph nodes under the arm and is extensive in the underarm lymph nodes (called Stage IIIa), or the cancer has spread to lymph nodes near the breastbone, muscles, and other tissues near the breast (called Stage IIIb). In stage IIIc, the tumors have spread to lymph nodes beneath the collarbone, lymph nodes near the neck, lymph nodes within the breast or under the arm, and to tissues near the breast. This stage may be operable dependent upon its location.
Stage IV: Stage IV is metastatic cancer. The cancer has spread beyond the breast and underarm lymph nodes to other parts of the body. The five-year survival rate for cancer diagnosed at this stage is 5 to 10%.
Recurrent cancer: Recurrent cancer means the disease has come back in spite of the initial treatment. Even when a tumor in the breast seems to have been completely removed or destroyed, the disease may return due to undetected cancer cells that remained in the body following treatment. Most recurrences appear within the first two or three years after treatment, but breast cancer can develop many years later.
Cancer appearing in the area of the original surgery is called a local recurrence. If the disease returns in another part of the body, the distant recurrence is called metastatic breast cancer. The patient may need a combination of treatments for recurrent cancer.
Infiltrating or invasive ductal: Infiltrating ductal is the most common type of breast cancer, representing 78% of all malignancies. These lesions can have a star-like appearance on mammography or be well rounded. The star-like lesions generally have a poorer prognosis.
Medullary carcinoma: Medullary carcinoma comprises 15% of breast cancers. These lesions are generally well circumscribed, but may be difficult to distinguish from fibroadenomas on mammography or sonography. Medullary carcinoma is estrogen and progesterone receptor (prognostic indicator) negative 90% of the time. Medullary carcinoma usually has a better prognosis than ordinary breast cancer.
Infiltrating or invasive lobular: Infiltrating lobular cancer represents 15% of breast cancers. The lesions are generally found in the upper outer quadrant of the breast as a slight thickening, and are difficult to diagnose by mammography. Infiltrating lobular cancer can occur bilaterally (involve both breasts).
Tubular carcinoma: Tubular carcinoma is categorized as an orderly or well-differentiated carcinoma of the breast. These lesions make up about 2% of breast cancer. They have a favorable prognosis with a ten-year survival rate of nearly 95%.
Mucinous carcinoma: Mucinous carcinoma has well rounded lesions, a favorable prognosis, and represents 1 to 2% of breast cancers.
Inflammatory breast cancer (IBC): IBC is a particularly aggressive type of breast cancer. It is usually found due to skin changes of the breast including redness (erythema), thickening of the skin, and prominence of the hair follicles resembling an orange peel. The diagnosis is made by a skin biopsy, which 50% of the time reveals tumors in the lymphatic and vascular channels. The five-year median survival rate for inflammatory breast cancer is approximately 40%.
Breast cancer is generally treated with surgery, irradiation, and chemotherapy.
Axillary, chemobrain, computer-aided detection, ductal carcinoma in situ (DCIS), ductal lavage, estrogen, fibroadenomas, fibrocystic, fine needle aspiration, HER-2/neu, infiltrating ductal, infiltrating lobular cancer, inflammatory breast cancer, invasive ductal, lumpectomy, lymph node, magnetic resonance imaging, mammography, mastitis, medullary carcinoma, metastatic, microcalcification, molecular breast imaging, mucinous carcinoma, peau d' orange, tubular carcinoma, ultrasonography.