breast cancer

The definitions used in this glossary of terminology either have been provided by the authors of the articles, or have been extracted wholly or in part, or paraphrased from the following sources: The American Medical Association Encyclopedia of Medicine, Charles B. Clayman, MD, Medical Editor, Random House, New York, 1989; Biotechnology from A to Z, 2d Edition, William Bains, Oxford University Press, New York, New York, 2002; A Dictionary of Genetics, 6th Edition, Robert C. King and William D. Stansfield, Oxford University Press, New York, New York, 2002; Dorland's Illustrated Medical Dictionary, 29th and 30th Editions, W. B. Saunders Company, Philadelphia, 2000, 2003; Genes VII, Benjamin Lewin, Oxford University Press, New York, New York, 2000; The Gale Encyclopedia of Genetic Disorders, Volumes I and II, Stacey L. Blachford, Ed., Thomson Learning, New York, New York, 2002; The Merriam-Webster Dictionary, Merriam-Webster, Inc., Springfield, Massachusetts, 1997; Molecular Biology of the Cell, 3rd Edition, Bruce Alberts, et al., Garland Publishing, 1994; The Random House Dictionary of the English Language, Unabridged Edition, 1966; Webster's Ninth New Collegiate Dictionary, 1991.

DEFINITION:

breast cancer
The most common cancer in women. Causes of breast cancer are believed to be due to either hormonal influences or diet. The incidence of breast cancer is known to be raised in women whose menstrual periods began when they were young and those whose menopause was late; in those who had no children or had their first child in their late 20s or 30s; and in those with mothers or sisters who had breast cancer. The dietary link is indicated also, however, for the disease is rare in Japan, which has a low fat diet, but Japanese women living in the US and eating an American diet have the same rate of breast cancer as Americans. Tall, heavy women have more breast cancer than short, thin ones. Breast cancer may also be more common among women who have previously had nonmalignant cysts and tumors removed from their breasts.


There is no agreement on the part played by the oral birth-control pill in the cause of breast cancer. Some groups believe that women who take the pill in their teens have a slightly increased risk; others claim that it is protective. At present the evidence suggests that any increase in breast cancer from the pill, if at all, is small---and that it is outweighed by the effect of the pill in lowering the incidence of cancers of the ovary and uterus.


The most common site of a malignant breast tumor is the upper, outer part of the breast. The lump is usually felt rather than seen, and in most cases is not painful. Other symptoms include a dark discharge from the nipple, retraction (indentation) of the nipple, and an area of dimpled, creased skin over the lump. In 90 percent of the cases only one breast is affected.


Monthly examination of the breasts should enable a woman to detect at an early stage any new or changed breast lump or any change in her nipples. The breast examination is important and should routinely be done by internists and gynecologists. In addition, X rays of the breasts, called mammograms, are recommended for high-risk women at age 40 and for all women after age 50.


A physician may determine that a lump is merely a cyst, in which case the lump (or sac) may be aspirated. If the physician suspects possible cancer, a biopsy will be performed and the suspect tissue examined under the microscope. If cancer is discovered, blood tests, X rays, and scanning will determine whether the disease has spread to other parts of the body.


Treatment usually includes surgical removal of the tumor, combined with radiation therapy or anticancer drug therapy, or both. The outlook is optimistic if detection is made early and cancer has not spread.

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