Booklet: What You Need to Know about Breast Cancer

The Promise of Cancer Research

Cancer research gives hope. Doctors and researchers at hospitals and medical centers all across the country are learning more about what causes breast cancer and are exploring ways to prevent it. They are also finding better ways to detect, diagnose, and treat this disease.

Causes and Prevention

Doctors can seldom explain why one person gets breast cancer and another doesn't. It is clear, however, that breast cancer is not caused by bumping, bruising, or touching the breast. And this disease is not contagious; no one can "catch" breast cancer from another person.

Scientists are trying to learn more about factors that increase the risk of developing this disease. For example, research is in progress to determine whether the risk of breast cancer is affected by environmental factors. Pesticides, magnetic fields, engine exhausts, and contaminants in water and food are some of the environmental factors under study. (The principal known risk factors are listed under Risk Factors for Breast Cancer.)

Some aspects of a woman's lifestyle may affect her chances of developing breast cancer. For example, some studies point to a slightly higher risk of breast cancer among women who drink alcohol. The risk appears to go up with the amount of alcohol consumed.

Scientists are trying to learn whether having an abortion or a miscarriage increases the risk of breast cancer. Thus far, studies have produced conflicting results, and this question is still unresolved.

Some evidence suggests a link between diet and breast cancer. Studies show that breast cancer is more common in populations that consume a high-fat diet than in populations that consume a low-fat diet. However, it is not yet known whether a diet low in fat will actually prevent breast cancer. Also, recent studies suggest that regular exercise may decrease the risk of breast cancer in younger women.

Research has led to the identification of certain alterations in genes that place women at a greater risk for developing breast cancer. Women with a strong family history of breast cancer may choose to have a blood test to see if they have inherited an alteration in the BRCA1 or BRCA2 gene. Certain alterations in either of these genes increase a woman's chances of developing breast cancer. Special counseling before and after testing helps women understand and deal with the possible outcomes--both benefits and risks--of having a genetic test. For example, a potential benefit of genetic testing is that it gives women the ability to make informed medical and lifestyle decisions. However, information about having a genetic alteration could affect a woman's employment or her health, life, and disability insurance. Women who are concerned about an inherited risk for breast cancer should talk to their doctor. The doctor may suggest seeing a health professional trained in genetics.

Ongoing studies are looking at ways to prevent breast cancer through changes in diet. Other studies are looking for drugs that may prevent the development of this disease. In one study, the drug tamoxifen reduced the number of new cases of breast cancer among women at an increased risk for the disease. For more information about this and other prevention clinical trials, call the Cancer Information Service.

Detection and Diagnosis

At present, mammograms are the most effective tool we have to detect breast cancer. Researchers are looking for ways to make mammography more accurate. They are also exploring other techniques, such as digital mammography (using computers to read mammograms), magnetic resonance imaging (MRI), breast ultrasonography, and breast-specific positron emission tomography (PET), to produce detailed pictures of the tissues in the breast.

In addition, researchers are studying tumor markers, substances that may be present in abnormal amounts in the blood, urine, or nipple aspirates of a woman who has breast cancer. Some of these markers are used to follow women who have already been diagnosed with breast cancer. At this time, however, no blood or urine test is reliable enough to be used routinely to detect breast cancer.

Clinical Trials

Research has led to significant advances in the treatment of breast cancer, and researchers continue to search for more effective ways to treat this disease. They are also exploring ways to reduce the side effects of treatment and improve the quality of patients' lives. When laboratory research shows that a new treatment method has promise, cancer patients receive the treatment in studies called clinical trials. These studies are designed to answer important questions and to find out whether the new approach is both safe and effective. Often, clinical trials compare a new treatment with a standard approach. Through research, doctors try to find new, more effective ways to treat cancer. Patients who take part in clinical trials may have the first chance to benefit from improved treatment methods, and they make an important contribution to medical science.

Studies of new approaches for patients with all stages of breast cancer are under way. A new procedure, sentinel lymph node biopsy, may eventually reduce the number of lymph nodes that need to be removed for biopsy and possibly prevent or lessen the severity of lymphedema. Researchers are also testing new chemotherapy doses and treatment schedules; the effectiveness of using chemotherapy before surgery (called neoadjuvant chemotherapy); and new ways of combining treatments, such as adding hormonal therapy or radiation therapy to chemotherapy. They are working with various anticancer drugs and drug combinations, as well as with several types of hormonal therapy. Some studies include biological therapy, treatment with substances that boost the immune system's response to cancer or help the body recover from the side effects of treatment.

In a number of studies, doctors are trying to learn whether very high doses of anticancer drugs are more effective than the usual doses in destroying breast cancer cells. Because these higher doses seriously damage the patient's bone marrow, where blood cells are formed, researchers are testing ways to replace the bone marrow or to help it recover. These new approaches (autologous bone marrow and peripheral blood stem cell transplants, and the use of colony-stimulating factors) are described in the Glossary section.

Cancer patients may want to read a National Cancer Institute booklet called Taking Part in Clinical Trials: What Cancer Patients Need To Know, which explains some of the possible benefits and risks of clinical trials. Those who are interested in taking part in a clinical trial should discuss this option with their doctor.

Women can learn about ongoing clinical trials through PDQ. This NCI cancer information database also contains current information on cancer prevention, screening, treatment, and supportive care. Information from PDQ is available from the Cancer Information Service and other sources listed under National Cancer Institute Information Resources.

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