Important Information
Cancer
Cancer is a general term that is used to describe a group of more than 100 diseases that cause cells in the body to divide and reproduce abnormally without control.
Normal body cells grow, divide, and die throughout a person's lifetime. After reaching adulthood, the growth of new cells is limited to replacement of worn-out or dying cells or to the repair of injured cells. Body cells sometimes continue to grow and divide abnormally, beyond the body's need for cell growth. These cells may join together to form a mass of extra tissue known as a tumor. Tumors can be malignant or benign. A malignant tumor is cancerous. Cells in malignant tumors can penetrate and destroy healthy body tissues. Cancer cells can also break away from tumors and travel, or metastasize, to other parts of the body through the bloodstream or lymph system. In this manner, cancer can spread and form secondary tumors in other parts of the body. A benign tumor is an abnormal growth that is not cancerous and does not spread to other sites in the body. Benign tumors can usually be removed and in most cases do not recur. In almost all instances, benign tumors are not life threatening.
Breast Cancer
Breast cancer refers to a malignant tumor that has developed from breast cells. Most cancers are classified according to the part of the body in which the cancer began, even if the cancer has metastasized to other parts of the body; therefore, if a cancer that develops in the breast spreads to the lung or another body part, it is still referred to as breast cancer or metastatic breast cancer.
There are two general categories of breast cancer: noninvasive, where the cancer cells are confined to the ducts (milk passages); and invasive, where the cancer cells have broken through the duct into the surrounding fatty and connective tissues. Within these categories, there are a number of unique cancer types, affecting different components of the breast.
Noninvasive Breast Cancers
Noninvasive forms of breast cancers are classified as ductal carcinoma in situ or lobular carcinoma in situ. Another form of breast cancer, Pagets's disease of the nipple, can be noninvasive or invasive.
Ductal carcinoma in situ (DCIS): Refers to cancer cells that are present in the duct that have not penetrated the duct walls into the surrounding tissue. This is the most common form of noninvasive breast cancer. It is also highly curable; nearly 100% of women diagnosed with this early form of cancer can be cured. A mammogram is the best method for detection of DCIS. It is treated with surgery or surgery plus radiation therapy. This type of cancer is also referred to as intraductal carcinoma.
Lobular carcinoma in situ (LCIS): LCIS is a very early type of breast cancer that develops within the lobules of the breast and does not penetrate through the wall of the lobules. Researchers think that LCIS cells almost never progress to invasive lobular cancer. However, having this type of cancer places a woman at increased risk of developing an invasive breast cancer later in life, in either breast. Women with this diagnosis should consult their physician to determine an appropriate screening program. This type of cancer is sometimes referred to as lobular neoplasia.
Paget's disease of the nipple: This is a rare form of breast cancer, accounting for just 1% of all breast cancer cases. It begins in the ducts and spreads to the skin of the nipple and areola. Symptoms may include crusted, scaly, red, or oozing skin of the affected area, as well burning or itching. Paget's disease can be associated with either in situ carcinoma or invasive breast carcinoma.
Invasive Cancers
Invasive breast cancers include infiltrating ductal carcinoma, infiltrating lobular carcinoma, inflammatory breast cancer, medullary carcinoma, mucinous carcinoma, phyllodes tumor, and tubular carcinoma.
Infiltrating (or invasive) ductal carcinoma (IDC): IDC is a cancer that starts in ducts of the breast and then breaks through the duct wall, where it spreads to the fatty tissue of the breast. It can also metastasize to other parts of the body through the bloodstream and lymphatic system. IDC, the most common type of invasive breast cancer, accounts for about 80% of breast malignancies.
Infiltrating (or invasive) lobular carcinoma (ILC): ILC is a cancer that starts in lobules of the breast and then breaks through the lobule walls to involve the nearby fatty tissue. From this site, it may then metastasize to other parts of the body. ILC accounts for approximately 10% to 15% of invasive breast cancers. It is often difficult to detect this breast cancer by physical examination or even by mammography.
Inflammatory breast cancer: This is a rare type of infiltrating carcinoma that has spread to lymphatic vessels in the skin covering the breast. Cancer cells blocking lymph vessels cause the skin of the affected breast to look red and feel warm. The skin may also thicken to the consistency of an orange peel. About 1% of invasive breast cancers are inflammatory carcinomas.
Medullary carcinoma: This is a special type of infiltrating ductal carcinoma with especially sharp boundaries between tumor tissue and normal tissue. The tumor also has larger than average cancer cells, with immune system cells present on the edges of the tumor. About 5% of breast cancers are medullary carcinomas.
Mucinous carcinoma: This is a rare type of invasive breast cancer that is formed by mucous-producing cancer cells which spread the disease into surrounding tissue.
Phyllodes Tumor: This is a very rare type of tumor that forms in the connective tissue of the breast and is generally benign, although there are rare instances of malignancy. In the malignant form, the phyllodes tumor is treated by surgically removing the tumor along with a wide margin of normal tissue, or by mastectomy. Phyllodes tumors are not responsive to hormonal therapy and are less responsive than other breast cancers to chemotherapy or radiation. Benign phyllodes are generally treated by removing the tumor and a narrow margin of surrounding tissue. Malignant phyllodes are treated in the same manner; however, a wider margin of tissue is removed. In some instances, mastectomy is the indicated treatment for malignant phyllodes tumor. Less than 10 women a year die of this form of breast cancer.
Tubular carcinoma: This is a special type of low grade infiltrating breast cancer that accounts for about 2% of invasive breast cancers.