Screening for cancer is examination (or testing) of people for early stages in the development of cancer even though they have no symptoms. Scientists have studied patterns of cancer in the population to learn which people are more likely to get certain types of cancer. They have also studied what things around us and what things we do in our lives may cause cancer. This information sometimes helps doctors recommend who should be screened for certain types of cancer, what types of screening tests people should have, and how often these tests should be done. Not all screening tests are helpful, and most have risks such as surgical biopsies to investigate an abnormal mammogram. For this reason, scientists at the National Cancer Institute are studying many screening tests to find out how useful they are and to determine the relative benefits and harms.
If your doctor suggests certain cancer screening tests as part of your health care plan, this does not mean he or she thinks you have cancer. Screening tests are done when you have no symptoms. Since decisions about screening can be difficult, you may want to discuss them with your doctor and ask questions about the potential benefits and risks of screening tests and whether they have been proven to decrease the risk of dying from cancer.
If your doctor suspects that you may have cancer, he or she will order certain tests to see whether you do. These are called diagnostic tests. Some tests are used for diagnostic purposes, but are not suitable for screening people who have no symptoms.
The purposes of this summary on breast cancer screening are to:
You can talk to your doctor or health care professional about cancer screening and whether it would be likely to help you.
The breast consists of lobes, lobules, and bulbs that are connected by ducts. The breast also contains blood and lymph vessels. These lymph vessels lead to structures that are called lymph nodes. Clusters of lymph nodes are found under the arm, above the collarbone, in the chest, and in other parts of the body. Together, the lymph vessels and lymph nodes make up the lymphatic system, which circulates a fluid called lymph throughout the body. Lymph contains cells that help fight infection and disease.
When breast cancer spreads outside the breast, cancer cells are most often found under the arm in the lymph nodes. In many cases, if the cancer has reached the lymph nodes, cancer cells may have also spread to other parts of the body via the lymphatic system or through the bloodstream.
More women in the United States get breast cancer than any other type of cancer (except for skin cancer). The number of cases per 1,000 women has increased slightly every year over the last 50 years. It is the second leading cause of death from cancer in women (lung cancer causes the most deaths from cancer in women). Breast cancer occurs in men also, but the number of new cases is small.
Anything that increases a person's chance of developing a disease is called a risk factor. Some of these risk factors for breast cancer are as follows:
Age: Breast cancer is more likely to develop as you grow older. Beginning menstruation at an early age and late age at first birth may also increase the risk of development of breast cancer.
History of Breast Cancer: If you have already had breast cancer, you are more likely to develop breast cancer again.
Family History: If your mother or sister had breast cancer, you are more likely to develop breast cancer, especially if they had it at an early age.
Radiation Therapy: Radiation therapy to the chest that was given more than 10 years ago, especially in women younger than 30 years old, may increase a woman's risk of developing breast cancer.
Other Breast Diseases: If you have had a breast biopsy specimen that showed certain types of benign breast conditions, you may be more likely to develop breast cancer. For most women, however, the ordinary "lumpiness" they feel in their breasts does not increase their risk of breast cancer.
Studies have found that race, social status, income, education, and access to screening and treatment services may affect a woman's risk of developing breast cancer.
Breast Self-Examination: When you examine your own breasts it is called breast self-examination (BSE). Studies so far have not shown that BSE alone reduces the number of deaths from breast cancer. Therefore, it should not be used in place of clinical breast examination and mammography.
Clinical Breast Examination: During your routine physical examination, your doctor or health care professional may do a clinical breast examination (CBE). During a CBE, your doctor will carefully feel your breasts and under your arms to check for lumps or other unusual changes.
Mammogram: A mammogram is a special x-ray of the breast that can often find tumors that are too small for you or your doctor to feel. Your doctor may suggest that you have a mammogram, especially if you have any of the risk factors listed above.
The ability of mammography to detect cancer depends on such factors as the size of the tumor, the age of the woman, breast density, and the skill of the radiologist.
Ultrasonography: During ultrasonography, sound waves (called ultrasound) are bounced off tissues and the echoes are converted into a picture (sonogram). Ultrasound is used to evaluate lumps that have been identified by BSE, CBE, or mammography. Studies have not shown that ultrasonography is of any proven benefit in detecting breast cancer.
Magnetic Resonance Imaging (MRI): A procedure in which a magnet linked to a computer is used to create detailed pictures of areas inside the body. MRIs are used to evaluate breast masses that have been found by BSE or CBE and to recognize the difference between cancer and scar tissue. The role of MRI in breast cancer screening has not yet been established.
Other screening methods are being studied. Your doctor can talk to you about what screening tests might be appropriate for you.
The PDQ cancer information summaries are reviewed regularly and updated as new information becomes available. This section describes the latest changes made to this summary as of the date above.
Changes were made to this summary.
For more information, U.S. residents may call the National Cancer Institute's (NCI's) Cancer Information Service toll-free at 1-800-4-CANCER (1-800-422-6237) Monday through Friday from 9:00 a.m. to 4:30 p.m. Deaf and hard-of-hearing callers with TTY equipment may call 1-800-332-8615. The call is free and a trained Cancer Information Specialist is available to answer your questions.
Web sites and Organizations
The NCI's Cancer.gov Web site provides online access to information on cancer, clinical trials, and other Web sites and organizations that offer support and resources for cancer patients and their families. There are also many other places where people can get materials and information about cancer treatment and services. Local hospitals may have information on local and regional agencies that offer information about finances, getting to and from treatment, receiving care at home, and dealing with problems associated with cancer treatment.
The NCI has booklets and other materials for patients, health professionals, and the public. These publications discuss types of cancer, methods of cancer treatment, coping with cancer, and clinical trials. Some publications provide information on tests for cancer, cancer causes and prevention, cancer statistics, and NCI research activities. NCI materials on these and other topics may be ordered online or printed directly from the NCI Publications Locator. These materials can also be ordered by telephone from the Cancer Information Service toll-free at 1-800-4-CANCER (1-800-422-6237), TTY at 1-800-332-8615.
The NCI's LiveHelp service, a program available on several of the Institute's Web sites, provides Internet users with the ability to chat online with an Information Specialist. The service is available from 9:00 a.m. to 10:00 p.m. Eastern time, Monday through Friday. Information Specialists can help Internet users find information on NCI Web sites and answer questions about cancer.
For more information from the NCI, please write to this address:
PDQ is a comprehensive cancer database available on Cancer.gov.
PDQ is the National Cancer Institute's (NCI's) comprehensive cancer information database. Most of the information contained in PDQ is available online at Cancer.gov, the NCI's Web site. PDQ is provided as a service of the NCI. The NCI is part of the National Institutes of Health, the federal government's focal point for biomedical research.
PDQ contains cancer information summaries.
The PDQ database contains summaries of the latest published information on cancer prevention, detection, genetics, treatment, supportive care, and complementary and alternative medicine. Most summaries are available in two versions. The health professional versions provide detailed information written in technical language. The patient versions are written in easy-to-understand, nontechnical language. Both versions provide current and accurate cancer information.
The PDQ cancer information summaries are developed by cancer experts and reviewed regularly.
Editorial Boards made up of experts in oncology and related specialties are responsible for writing and maintaining the cancer information summaries. The summaries are reviewed regularly and changes are made as new information becomes available. The date on each summary ("Date Last Modified") indicates the time of the most recent change.
PDQ also contains information on clinical trials.
People who are at high risk for a certain type of cancer may want to take part in a clinical trial. A clinical trial is a study to answer a scientific question, such as whether a method of finding cancer earlier can help people to live longer. Trials are based on past studies and what has been learned in the laboratory. Each trial answers certain scientific questions in order to find new and better ways to help cancer patients and those who are at risk for cancer. During screening clinical trials, information is collected about screening methods, the risks involved, and how well they do or do not work. If a clinical trial shows that a new method is better than one currently being used, the new method may become "standard."
Listings of clinical trials are included in PDQ and are available online at Cancer.gov. Descriptions of the trials are available in health professional and patient versions. Many cancer doctors who take part in clinical trials are also listed in PDQ. For more information, call the Cancer Information Service 1-800-4-CANCER (1-800-422-6237); TTY at 1-800-332-8615.Physicians version: CDR0000062751