breast cancer

Malignant tumour in a breast, usually in women after menopause.

Risk factors include family history of breast cancer, prolonged menstruation, late first pregnancy (after age 30), obesity, alcohol use, and some benign tumours. Most breast cancers are adenocarcinomas. Any lump in the breast needs investigation because it may be cancer. Treatment may begin with radical or modified mastectomy or lumpectomy (in which only the tumour is removed), followed by radiation therapy, chemotherapy, or removal of the ovaries or adrenal glands.

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▪ disease

Introduction

      disease characterized by the growth of malignant cells in the mammary glands (mammary gland). Breast cancer can strike males and females, although women are about 100 times more likely to develop the disease than men. Most cancers (cancer) in female breasts form shortly before, during, or after menopause, with three-quarters of all cases being diagnosed after age 50. Generally, the older a woman is, the greater is her likelihood of developing breast cancer. Worldwide, breast cancer is the most common cancer among women, and in North America and Western Europe, where life spans are longer, the incidence is highest. For instance, it is estimated that over 10 percent of all women in the United States will develop the disease at some point in their lives.

Causes and symptoms

      The exact causes of breast cancer are largely unknown, but both environmental and genetic factors are involved. A family history of breast cancer increases risk. Specific mutations (mutation) in genes called HER2, BRCA1, BRCA2, and p53 have been linked to breast cancer; these mutations may be inherited or acquired. Prolonged exposure to the hormone estrogen, as when menstruation starts before age 12 and continues beyond age 50, favours development of cancer, and women who have had certain kinds of benign tumours (tumour) are also more prone to developing breast cancer. Other risk factors may include lack of exercise, use of oral contraceptives, alcohol consumption, and previous medical treatments involving chest irradiation.

      The most common symptom of breast cancer is an abnormal lump or swelling in the breast, but lumps may also appear beside the breast or under the arm. Other symptoms may include unexplained breast pain, abnormal nipple discharge, changes in breast texture, or changes in the skin on or around the breast.

Diagnosis

      Early diagnosis greatly improves the odds of survival. When detected early, breast cancer has a very high five-year survival rate, and patients who reach this stage often go on to live long, healthy lives. Survival rates are lower for cancers that have spread locally, and they are very low for cancers that have metastasized, or spread, to distant parts of the body.

      Breast cancer may be first discovered by the patient as the result of a regular breast self-examination. A breast X ray (X-ray) (mammogram) is often used for initial diagnosis, but in order to confirm the presence of cancer, a tissue sample ( biopsy) usually must be taken. If cancer is suspected to have spread to nearby lymph nodes, they must also be sampled.

      Once cancer has been diagnosed, the tumour's type and degree of invasiveness is assessed. Several imaging methods may be used to determine the degree of metastasis, including X rays, computed tomography (computerized axial tomography) (CT) scans, or magnetic resonance imaging (diagnosis) (MRI). The presence of receptors for the hormones estrogen and progesterone is also determined because these receptors play an important role in the cancer's development and in decisions regarding the appropriate treatment.

      Almost all cases of breast cancer begin in the glandular tissues that either produce milk (lobular tissue) or provide a passage for milk (ductal tissue) to the nipple. Cancers of these tissues are called lobular carcinomas and ductal carcinomas. Because these tissues are glandular, both cancers are called adenocarcinomas. The most common type of tumour, called infiltrating ductal carcinoma, is a single hard, barely movable lump. This type of tumour accounts for about 70 percent of all cases. Fewer than 15 percent of all cases are lobular carcinomas (carcinoma).

      There are several other types and subtypes of tumour classified and named according to several criteria, including their outward appearance, cellular composition, cellular origin, and activity.

      Paget disease is an uncommon type of breast cancer that begins at the nipple and initially causes a burning, itching, or tender sensation. Eventually the lesion becomes enlarged, cracks, oozes, and forms crusts.

      Inflammatory carcinoma is a rare type of breast cancer that results in swelling and reddening of the affected area. The area then becomes purplish, and the skin is hot, with the nipple usually becoming crusted and retracted.

Treatment (therapeutics)

      Any lump found in the breast should be examined by a physician for the possibility of cancer. If it is found to be malignant, treatment may entail surgery, radiation, or chemotherapy. Biological treatment is also an option.

       surgery is often the first method of treatment, and a range of procedures are used depending on the type and progression of the cancer. A lumpectomy removes only the cancerous mass and a small amount of surrounding tissue; a simple mastectomy removes the entire breast; and a modified radical mastectomy removes the breast along with adjacent lymph nodes. Radical mastectomies involving removal of the breast, underlying muscle, and other tissue are rarely performed. Side effects of surgery may include changes in arm or shoulder mobility, swelling, infection, and numbness. When lymph nodes are removed, fluid may build up in the region they were taken from. Partial or complete breast removal is often followed by cosmetic or reconstructive surgery.

      Radiation (radiation therapy) is usually employed—either before surgery to shrink tumours or following surgery to destroy small amounts of remaining cancerous tissue. Side effects of radiation include swelling or thickening of the breast, vomiting, fatigue, diarrhea, or skin irritations resembling sunburn. chemotherapy, the use of chemicals to destroy cancerous cells, is commonly employed. Chemotherapeutic agents also attack normal cells to some degree, causing side effects that include hair loss, immune suppression, mouth sores, fatigue, and nausea.

      Breast cancer can also be treated through biological therapy, in which chemical inhibitors are used to block the hormones that stimulate growth of cancer cells. tamoxifen, for instance, is a common drug that blocks the ability of estrogen to stimulate tumour growth, and Megace blocks the action of progesterone by partially mimicking the hormone. Herceptin is a manufactured antibody that binds to growth factor receptors on the surface of cancer cells and thereby blocks cell proliferation.

Prevention

      Breast cancer cannot be completely prevented, but the risk of developing advanced disease can be greatly reduced by early detection. Medical societies recommend a monthly breast self-examination for all women over the age of 20, a breast exam by a health care professional every three years for women 20–39 years old, and a yearly mammogram for all women 40 and older. Women at high risk of developing breast cancer may benefit from taking tamoxifen to reduce their risk. Women who are at extreme risk, as determined by a very strong family history or the presence of mutated BRCA genes, may opt for preventive mastectomy.

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