Date reviewed: 05/3/2002 Screening Mammograms: Questions and Answers
A screening mammogram is an x-ray of the breast used to detect breast changes in women who have no signs or symptoms of breast cancer. It usually involves two x-rays of each breast. With a mammogram, it is possible to detect microcalcifications (tiny deposits of calcium in the breast, which sometimes are a clue to the presence of breast cancer) or a tumor that cannot be felt.
A diagnostic mammogram is an x-ray of the breast that is used to diagnose unusual breast changes, such as a lump, pain, thickening, nipple discharge, or a change in breast size or shape. A diagnostic mammogram is also used to evaluate changes detected on a screening mammogram. This type of mammogram may be necessary if it is difficult to obtain a clear x-ray with a screening mammogram because of special circumstances, such as the presence of breast implants (see question 12). A diagnostic mammogram takes longer than a screening mammogram because it involves more x-rays to obtain views of the breast from several angles. The technician may magnify a suspicious area to produce a detailed picture that can help the doctor make an accurate diagnosis.
The risk of breast cancer increases gradually as a woman gets older. However, the risk of developing breast cancer is not the same for all women. Research has shown that the following factors increase a woman’s chance of developing this disease:
Age is the most important risk factor for breast cancer. The older a woman is, the greater her chance of developing breast cancer. A woman’s chance of being diagnosed with breast cancer is:*
Most breast cancers occur in women over the age of 50; the number of cases is especially high for women over age 60. Breast cancer is relatively uncommon in women under age 40. A high-quality mammogram with a clinical breast exam (an exam done by a health care provider) is the most effective way to detect breast cancer early. Like any test, mammograms have both benefits and limitations. For example, some cancers cannot be detected by mammogram, but may be detectable by breast examination. Checking one’s own breasts for lumps or other unusual changes is called breast self-exam (BSE). Studies so far have not shown that BSE alone reduces the numbers of deaths from breast cancer. BSE should not take the place of clinical breast exam and mammography. Mammograms can detect breast cancer that cannot be felt. Several large studies conducted around the world show that breast cancer screening with mammograms reduces the number of deaths from breast cancer for women ages 40 to 69, especially those over age 50. Studies conducted to date have not shown a benefit for regular screening mammograms, or for a baseline screening mammogram, in women under age 40. Over the past 30 years, improvements in mammography have resulted in an ability to detect a higher number of tissue abnormalities called DCIS. DCIS contains abnormal cells that are confined to the milk ducts of the breast. The cells have not invaded the surrounding breast tissue. Eighty percent of cases of DCIS are found by mammography because DCIS usually does not cause a lump that can be felt. Some of these cases later become invasive cancers. Today, it is not possible to predict which cases of DCIS will progress to invasive cancer. Therefore, DCIS is usually removed surgically. Until recently, DCIS was often treated with mastectomy, but breast-conserving surgery is now an option for many women with DCIS. Radiation therapy, with or without tamoxifen, also may be used. Women who have been diagnosed with DCIS should talk with their doctor to make an informed decision about treatment. Screening mammograms generally cost between $100 and $150. Most states now have laws requiring health insurance companies to reimburse all or part of the cost of screening mammograms. Details can be provided by insurance companies and health care providers. Medicare pays 80 percent of the cost of a screening mammogram each year for beneficiaries age 40 and older and one baseline mammogram for beneficiaries age 35 to 39. There is no deductible requirement for this benefit, but Medicare beneficiaries are responsible for a 20 percent copayment of the Medicare-approved amount. Information about Medicare coverage is available at http://www.medicare.gov on the Internet, or through the Medicare Hotline at 18006334227 (1800MEDICARE). For deaf and hard of hearing callers, the TTY/TDD number is 18774862048. Some state and local health programs and employers provide mammograms free or at low cost. For example, the Centers for Disease Control and Prevention (CDC) coordinates the National Breast and Cervical Cancer Early Detection Program. This program provides screening services, including clinical breast exams and mammograms, to low-income women throughout the United States and in several U.S. territories. Contact information for local programs is available on the CDC’s Web site at http://www.cdc.gov/cancer/nbccedp/contacts.htm on the Internet, or by calling the CDC at 18888426355 (select option 7). Information on low-cost or free mammography screening programs is also available through the NCI’s Cancer Information Service (CIS) at 18004CANCER (18004226237). Women can get high-quality mammograms in breast clinics, radiology departments of hospitals, mobile vans, private radiology offices, and doctors’ offices. The Mammography Quality Standards Act (MQSA) is a Federal law designed to ensure that mammograms are safe and reliable. Through the MQSA, all mammography facilities in the United States must meet stringent quality standards, be accredited by the Food and Drug Administration (FDA), and be inspected annually. The FDA ensures that facilities across the country meet MQSA standards. These standards apply to the following people at the facility: All mammography facilities are required to display their FDA certificate. Women should look for the MQSA certificate at the mammography facility and check its expiration date. Women can ask their doctors or staff at the mammography facility about FDA certification before making an appointment. MQSA regulations also require mammography facilities to give patients an easy-to-read report on the results of their mammogram. Information about local FDA-certified mammography facilities is available through the CIS at 18004CANCER (18004226237). Also, a list of these facilities is on the FDA’s Web site at http://www.fda.gov/cdrh/mammography/certified.html on the Internet. Women with breast implants should continue to have mammograms. (A woman who had an implant following breast cancer surgery should ask her doctor whether a mammogram of the reconstructed breast is necessary.) It is important to inform the facility about breast implants when scheduling a mammogram. The technician and radiologist must be experienced in x-raying patients with breast implants. Implants can hide some breast tissue, making it more difficult for the radiologist to detect an abnormality on the mammogram. If the technologist performing the procedure is aware a woman has breast implants, steps can be taken to make sure that as much breast tissue as possible can be seen on the mammogram. Digital mammography records x-ray images in computer code instead of on x-ray film, as with conventional mammography. In January 2000, the FDA approved a digital mammography system that may offer potential advantages over the use of standard x-ray film. Research studies so far have not shown that digital images are more effective in finding cancer than x-ray film images. However, NCI is directing additional studies to learn whether digital mammography is as good as or better than conventional mammography. Digital mammography may offer the following advantages over conventional mammography:
Currently, digital mammography can be done only in facilities that are certified to practice conventional mammography and have received FDA approval to offer digital mammography. The procedure for having a mammogram with a digital system is the same as with conventional mammography. The NCI is supporting the development of several new technologies to detect breast tumors. This research ranges from methods under development in research labs to those that have reached the stage of testing in humans (in studies known as clinical trials). Efforts to improve conventional mammography include digital mammography (see question 13), magnetic resonance imaging (MRI), and positron emission tomography (PET scanning). In addition to imaging technologies, NCI-supported scientists are exploring methods to detect markers of breast cancer in blood, urine, or nipple aspirates (fluid from the breast) that may serve as early warning signals for breast cancer. The NCI fact sheet Improving Methods for Breast Cancer Detection and Diagnosis provides more information about technologies that are under development for breast cancer screening and diagnosis. This fact sheet is available at http://cis.nci.nih.gov/fact/5_14.htm on the Internet, or can be ordered from the CIS at 18004CANCER (18004226237). NCI is supporting many studies that are looking for improved prevention and treatment of breast cancer.
Women who would like more information on cancer prevention, treatment, or screening studies can call the CIS at 18004CANCER (18004226237). Sources of National Cancer Institute Information
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