Breast Cancer

All of the organs in our bodies are made up of cells, which normally divide in an orderly manner to form new cells as needed. However, when a person develops cancer, cells become abnormal and begin to divide without control or order. Increased cell division creates extra tissue, called a tumor.

Other factors besides cancer can cause abnormal cell division and tumors. When cancer is not the cause of a tumor, the tumor is called benign. Benign tumors can usually be removed and generally do not come back. Most importantly, the cells in benign tumors do not invade other tissues and do not spread to other parts of the body. Benign breast tumors are not life-threatening.

When cancer is the cause of a tumor, the tumor is called malignant. Malignant tumors can invade and damage nearby tissues and organs. Cancer cells can also break away from the malignant tumor and enter the blood stream or lymphatic system. By this process, breast cancer spreads and forms secondary tumors in other parts of the body. The spread of cancer is called metastasis.

There are several types of breast cancer. The most common, ductal carcinoma, begins in the lining of the ducts that link the lobules of the breast to the nipple. Another type, lobular carcinoma, begins in the large sections of the breast called lobules. Cancers that begin in other tissues in the breast are rare.

When breast cancer metastasizes, it is often found in the lymph nodes under the arm. If the cancer has reached the nodes, it may mean that cancer cells have spread to other parts of the body. Though the cancer has spread to other organs and lymph nodes, it is still called breast cancer. Doctors may call this metastatic breast cancer or "distant" disease.

The course of breast cancer
Diagnosis and early detection
Treatment
Living with cancer
Making the right decisions