Description
Breast cancer is a malignant tumor that develops from cells in the breast. It is the most common cancer among women, other than skin cancer, and it is the second leading cause of cancer-related death in women.
Symptoms of breast cancer include a lump or mass, swelling, skin irritation or dimpling, nipple pain or retraction, redness or scaliness of the nipple or breast skin, or discharge (other than breast milk).
Statistics
In 2004, an estimated 215,990 new cases of invasive breast cancer are anticipated among women in the United States; about 1,450 in men. An additional 59,390 new cases of in situ breast cancer are expected during that period – about 85 percent of which are ductal carcinoma in situ (DCIS).
About two million women in the U.S. are living with diagnosed breast cancer. Incidence rates have risen consistently since 1980, though at a slower rate in the 1990s, compared to the 1980s, and only in women age 50 and over since 1986.
White women are more likely to develop breast cancer than black women, but more black women than white die from the disease. There is a racial discrepancy in the five-year survival rate for women diagnosed with invasive breast cancer, as well: 88 percent for whites versus 74 percent for blacks.
Overall, breast cancer claims the lives of about 40,110 women each year, along with more than 400 men. Mortality rates have declined a little more than two percent per year between 1990 and 2000, with more rapid decreases in younger women.
Early Detection and Diagnosis
Women are recommended to begin the practice of monthly breast self-examination while in their 20s. This practice should be augmented by a clinical breast examination, conducted by a health care professional in the course of a routine exam, ideally every three years. After age 40, women should have a breast exam by a health expert every year.
Mammography currently is the most effective tool to detect changes in breast tissue that may signal cancer and occur before symptoms present. Women age 40 and older should have a mammogram every year, and should continue to do so for as long as they are in good health.
A study is underway to compare the relative accuracy of standard mammography – which captures an image on X-ray film – and digital mammography, which stores the image in a computer. The new technology holds promise for even more effective breast cancer diagnosis, since the digital images can be adjusted, manipulated and enhanced for a more thorough and accurate view of what may be abnormal tissue.
Other existing imaging techniques are being evaluated for their potential both to diagnose breast cancer and provide information about tumors that can be used to help guide treatment decisions. These include magnetic resonance imaging, positron emission tomography and Sestamibi scintimammography.
Ductal lavage is another screening option in development. Using a catheter, a salt water solution is injected into the opening of a milk duct on the surface of the nipple. When the solution is withdrawn, it carries cells from inside the ducts that then are analyzed under a microscope for breast cancer or changes suggestive of impending cancer.
Minimizing Risk/Prevention
No one knows what causes breast cancer or who will develop it, and there is no proven means of prevention or cure. What scientists can identify are characteristics held in common by women who develop breast cancer. These include such factors beyond our control as age; family history of breast cancer – including inheriting a mutation in one of the two breast-cancer related genes, BRCA-1 or BRCA-2; early onset of menses or late age at menopause; as well as some personal choices like recent use of oral contraceptives; never having children or having children after age 30; obesity after menopause and use of combined estrogen and progesterone hormone replacement therapy.
Researchers are examining ways women can reduce their risk of breast cancer, including eating a diet rich in fruits and vegetables and low in fat, maintaining a healthy body weight and undertaking regular exercise. Michelle D. Holmes, M.D., Dr. P.H., has done research indicating that women who engage in even moderate physical activity after being diagnosed with breast cancer appear to improve their chances of survival.
A closer look at how hormones, in general and during pregnancy, influence the development of breast cancer is underway, as are studies of whether environmental factors contribute to breast cancer risk.
Still and all, the known risk factors for breast cancer account for fewer than 20 percent of cases, and a family history is a factor only about ten percent of the time.
Latest Research
Immunotherapies clearly are necessary to improve outcomes in breast cancer cases, which frequently recur or progress despite various and aggressive therapies. Cancer vaccines have the potential to both treat existing cancer and prevent its recurrence. In addition, breast cancer vaccines may be an ideal intervention for preventing ductal carcinoma in situ (DCIS), a very early form of breast cancer, from progressing.
About half of DCIS tumors and a third of invasive breast cancers carry a protein called HER-2/neu on the outside of the cancer cells. Axel Ullrich, Ph.D., first identified and characterized HER-2/neu in 1985. Dennis J. Slamon, M.D., Ph.D., established the relationship between the HER-2/neu gene and a particularly aggressive form of breast cancer. High levels of HER-2/neu may affect the resistance or sensitivity of tumors to chemotherapy and hormonal therapy. Tumors that express HER-2/neu also are effective targets for the biological therapy drug, trastuzumab (Herceptin). Slamon conducted the initial research leading to the development of Herceptin, and oversaw the drug through Phase III clinical trials and government approval.
Scientists are looking also for drugs that may prevent breast cancer. The research of V. Craig Jordan, Ph.D., D.Sc., resulted in the development of tamoxifen for the treatment of breast cancer, and led to its use as the first breast cancer preventive agent. In one large study, the drug tamoxifen reduced the number of new cases of breast cancer among women who were at an increased risk of the disease.
In addition, researchers are studying tumor markers – substances that may be present in abnormal amounts in people with cancer. Tumor markers can be measured in blood or urine, or in fluid from the breast. Some are used to check for signs of disease after treatment in breast cancer patients. At this time (March 2005), however, no tumor marker test is reliable enough to be used routinely to detect breast cancer.
At the molecular level, scientists like Lewis A. Chodosh, M.D., Ph.D., are using genomics and computational approaches to define the changes that occur in the breast during developmental stages that influence breast cancer risk, study the regulatory molecules that control development and contribute to cancer, and create genetically engineered mouse models to investigate the processes by which breast cancers arise.
Current Treatment
The treatment options for breast cancer are removal of the tumor (lumpectomy), the breast (mastectomy) and, in some instances, the lymph nodes under the arm; radiation therapy; chemotherapy; hormonal therapy; and biological therapy. Two or more methods often are used in combination.
Since estrogen plays a critical role in the development and progression of hormone-dependent breast cancer, scientists including Judy E. Garber, M.D., MPH, are investigating the therapeutic potential of the inhibitors that target the enzymes responsible for stimulating estrogen production in the breast.
Others are exploring ways to lessen the side effects of treatment, such as postoperative swelling and pain, and to improve the quality of patients' lives. In an effort to decrease the number of lymph nodes removed in breast cancer surgery, surgeons are injecting dye and radioactive material into the tissue adjacent to the tumor and tracking their flow to the lymph node or nodes to which cancer cells are likely to spread first. Then only the marked node or nodes are removed for biopsy.
Resources
Susan G. Komen for the Cure
1-800-I’M AWARE
www.komen.org
National Cancer Institute
1-800-4-CANCER
www.cancer.gov
American Cancer Society
1-800-ACS-2345
www.cancer.org
National Breast Cancer Coalition
1-800-622-2838
www.natlbcc.org