National Cancer Institute's Breast Cancer Backgrounder

October 5, 1999 -- Breast cancer is the most frequently diagnosed non-skin cancer among women in the United States. It is second only to lung cancer in cancer-related deaths. Approximately 180,000 new cases of breast cancer will be diagnosed in 1997, and about 44,000 women are expected to die from the disease. Five to 10 percent of these cases will be inherited forms of breast cancer.

Between 1982 and 1987, breast cancer incidence (rate of new cases) for women increased about 4 percent per year, but recently has leveled off. The death rate for women with breast cancer declined 6.3 percent between 1991 and 1995. The greatest reductions in death rates were among younger women (9.3 percent) and white women (6.6 percent), with more modest reductions among African Americans (1.6 percent) and women age 65 and older (2.8 percent).

Advances

Understanding Risk.

Scientists now understand that certain factors, such as family history and exposure to hormones, influence a woman's risk for breast cancer. In the past few years, scientists have found that alterations in two important genes, BRCA1 and BRCA2, are responsible for up to 90 percent of inherited breast cancer, which is estimated to account for 5 to 10 percent of all breast cancers.

Early Detection.

• Improved mammography screening techniques and better imaging technologies, such as ultrasound and computed tomography, are now used in diagnosis, sparing some women of surgical biopsy.
• Due to improved diagnostic techniques, women today are more likely to be diagnosed when breast cancer is small or restricted to the breast.

Treatment Decisions.

Today, a woman receives her diagnosis in an outpatient setting, enabling her to make treatment decisions together with her doctor. Much more information from government and voluntary groups is now available to aid in decision making.

Treatment.

Thanks to clinical research, major changes have occurred in treatment, including:

• Mastectomy has been replaced by less radical surgery for women with early stage cancer.
• Chemotherapy or hormonal therapy in addition to surgery has improved disease-free and overall survival for many breast cancer patients.

Follow-Up Care.

An organized follow-up program after treatment is a routine part of care. In addition:

• Significant advances in breast reconstruction techniques provide women with a variety of options.
• Psychosocial aspects of care are more accepted as an integral part of the continuum of care.

Quality of Life.

Most women today have treatment options -- breast-conserving surgery with radiation or mastectomy -- as a result of clinical research that showed equivalent recurrence and survival rates for mastectomy compared to lumpectomy plus radiation.

Opportunities

Risk.

Many studies are under way to identify the causes of breast cancer, including:

• One important approach is analysis of the role that alterations in BRCA1 and BRCA2 play in the development of cancer.
• In addition, it will be important to understand the role of normal BRCA1 and BRCA2 genes in normal breast and ovary cells and the way these genes act to protect cells from becoming malignant.
• Scientists also are studying how these genes interact with other genes and with hormonal, dietary, and environmental factors to influence which cancers will develop and when.
• Researchers are also working on strategies to prevent cancers in high-risk individuals. The same strategies could also be effective in preventing cancers in all women.
• Ethical, legal, and social implications of these revolutionary developments are also being examined.

Prevention.

Researchers are looking for ways to prevent breast cancer in women at high risk, including:

• A large study is under way to see if the drug tamoxifen will reduce cancer risk in women age 60 or older and in women age 35 to 59 who have a pattern of risk factors for breast cancer. This study is also a model for future studies of cancer prevention. Studies of diet and nutrition could also lead to preventive strategies.

Early Detection.

• Several new breast cancer early detection techniques are in the research stage. Examples are magnetic resonance imaging (MRI), positron emission tomography, and laser beam scanning.

Treatment.

The challenge is to make treatment more targeted and effective, and less toxic.

Scientists are studying:

• High-dose chemotherapy with bone marrow or stem cell transplantation to determine how this therapy can be used most effectively.
• Biological therapies, such as the HER2/neu antibody, which could be more effective and have milder side effects than other treatments.

Additional Reading

"Breast Cancer," Seminars in Oncology. W.B. Saunders Company, August 1996.

NOTE: Statistics are from the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) database (January 1997) and from the American Cancer Society's Cancer Facts and Figures-1997, which contains estimates based on SEER data.

March 7, 1997
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