Aside from nonmelanoma skin cancer, breast cancer is the most common type of cancer found in women. Approximately one out of every seven women will develop breast cancer at some point in their lives and the condition is the second leading cause of death in women, with approximately 3 percent (1 in 33) of women dying from the condition. The risk of developing breast cancer increases after a woman reaches forty years of age, and most breast cancer cases occur in women who are over age 50.
It has been estimated that in the year 2004, just over 40,000 women and almost 500 men will be killed by breast cancer in the United States alone. Though the numbers of breast cancer-related deaths are still high, these deaths have been steadily decreasing and can continue to do so with increased public awareness and practices that allow early detection such as regular mammograms and a self-examination routine.
To understand breast cancer, it's necessary to understand how cancer develops as well as the structure of the breast. Cancer develops when the DNA of normal cells become damaged, creating cancerous cells. While normal cells grow, multiply, and divide, cancer cells outlive normal cells and divide at an advanced pace, creating even more cancer cells. Breast cancer occurs when these cancerous cells begin to multiply and outlive normal cells in the breast.
Breast cancer can develop in both men and women, though there are differences between the structure of a man's breast and a woman's breast. The female breast is mostly made up of three different components; the lobules, the ducts and the stroma. The lobules are the glands in the breast which produce milk when a woman is nursing and the ducts are the passages that connect the lobules to the nipple, allowing the milk to flow to the surface of the nipple. The stroma is the fatty tissue of the breast that surrounds the lobules and the ducts. Most breast cancer will develop as tumors in the ducts of the breast, although it is possible for cancer to develop in the lobules and the stroma as well. If not caught early and treated in time, it is possible for breast cancer to spread to other areas of the body, especially the lymph nodes near the breasts.
It is important to understand that not all lumps in the breast are cancerous tumors. In fact, most of the lumps that are discovered in the breast are benign (non cancerous) and are a result of fibrocystic changes; although some benign breast tumors can indicate an increased risk of developing breast cancer at some point. There a number of different types of breast cancer, including ductal carcinoma in situ, lobular carcinoma in situ, invasive ductal carcinoma, invasive lobular carcinoma, inflammatory breast cancer, medullary carcinoma, mucinous carcinoma, phyllodes tumor, tubular carcinoma, and Paget's disease of the nipple. The most common diagnosis of breast cancer is ductal carcinoma in situ, which accounts for approximately 20 percent of all new cancer cases.
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