NIH Press Release
National Cancer Institute

Thursday, March 6, 1997

NCI Press Office
(301) 496-6641

Questions and Answers on Mammography for Women Ages 40 to 49

  1. Why was a consensus conference held on mammography for women ages 40 to 49?

    After reviewing preliminary data from updated Swedish screening studies presented at a meeting in March 1996, the National Cancer Institute (NCI) staff requested a consensus conference. The data showed that women beginning regular mammograms at some time in their 40s had a 23 percent decrease in breast cancer deaths. By inviting the principal investigators from eight large-scale randomized screening trials (including the Swedish investigators) to participate, the staff thought that the new findings might show a consistent benefit to this age group that had not been seen before.

    In choosing the format of an National Institutes of Health Consensus Development Conference, NCI staff used a well-established mechanism set up in 1977 to resolve controversial topics in medicine. The Office of Medical Applications of Research (OMAR), a part of the National Institutes of Health (NIH), assembles a "science court" where a group of scientific experts presents data to an impartial panel that serves as a jury. OMAR is responsible for selecting speakers who represent all sides of the controversy and panel members from diverse professional disciplines with no scientific conflict or commercial interest in the conference's outcome.

    The principal task of the panel is to develop answers to questions prepared by a planning committee several months in advance of the conference. The final consensus statement reflects solely the opinions of the panel, is independent of NCI, NIH, or any government body, and is intended to be useful to health professionals, the public, and government agencies. The conference was held Jan. 21-23, 1997.

  2. What was the outcome of the consensus conference?

    The panel found that the data presented at the meeting did not warrant a single recommendation for mammography screening for all women in their 40s and that each woman should decide for herself, in consultation with a health professional, whether to undergo mammography. Recognizing both the importance and complexity of the issues involved in assessing the evidence, the panel stated that women should have access to the best possible information in an understandable and usable form describing the risks and benefits of mammography screening. The panel also stated that if a woman wishes to have a mammogram, there should be no impediments to her choice, and third party payers should provide coverage. The draft consensus statement includes a description of the risks and benefits of mammography screening. The final version is expected to be available soon.

  3. What is the next step in the process to define NCI's position on mammography screening for women aged 40 to 49?

    On Feb. 25, The National Cancer Advisory Board (NCAB) began a discussion of the issues surrounding mammography screening for women. At the end of a two hour session, the NCAB, recognizing the importance and complexity of the topic, decided to form a Working Group composed of board members to develop clear recommendations to the NCI. The NCAB will recommend what message the NCI should clearly communicate to women and health care providers, and what products are needed to clearly communicate the message and facilitate a woman's individual choice through informed decision making. The board intends to complete the process within two months. In addition, the board will consider whether there should be a formal monitoring structure to review on an ongoing basis, data from randomized clinical trials that are evaluating screening mammography.

  4. Why will it take the NCAB subcommittee up to two months to come up with a recommendation?

    NCAB members are primarily non-government scientists and experts. This is an extremely important but complex topic. The members vary in their prior familiarity with the topic. The process will require some time to permit the members to review the relevant literature. This presidentially appointed board provides advice to the NCI in addition to their other professional commitments. A small working group of NCAB members has volunteered to prepare, within two months, a guidance document that will describe some of the next steps that the NCI should take, such as:

    • What message can the NCI give to women and their health care providers concerning the range of uncertainty about the benefits and risks of mammography for women in their 40s;
    • What types of communication products will be needed for truly informed decision-making;
    • How can the NCI monitor studies on an ongoing basis for new information concerning risks and benefits.

    The NCAB Working Group will be co-chaired by Frederick P. Li, M.D., and Robert W. Day, M.D., Ph.D. Dr. Li is chief of cancer epidemiology and control at the Dana-Farber Cancer Institute, Boston. Dr. Day is president and director of the Fred Hutchinson Cancer Research Center, Seattle.

    Other NCAB members on the Working Group are: Nobel Laureate J. Michael Bishop, M.D., director of the Hooper Research Foundation at the University of California, San Francisco, Kay Dickersin, Ph.D., associate professor of epidemiology and preventive medicine at the University of Maryland, Baltimore; Barbara Gimbel, The Society of the Memorial Sloan-Kettering Cancer Center, New York; Ellen Stovall, executive director of the National Coalition of Cancer Survivorship, Silver Spring, Md.; and Sandra Millon-Underwood, Ph.D., associate professor of nursing, University of Wisconsin, Milwaukee.

    Dr. Barbara Rimer, chair of the NCAB, who is professor and director of cancer prevention, detection and control research at Duke University, and will also serve on the Working Group. Dr. Dickersin is also co-chair of the Research Task Force of the National Breast Cancer Coalition.

  5. What are the responsibilities of the NCAB?

    The NCAB is a presidentially appointed committee that advises, assists, and consults with the NCI director with respect to NCI activities and policies. The NCAB includes both scientists in various areas of laboratory and clinical research, and lay persons from the community at large. The NCAB meets quarterly and is composed of 18 non-federal members appointed by the president and 12 non-voting ex officio federal members.

  6. Why did NCI withdraw its recommendation for mammography screening of 40 to 49-year-old women in 1993?

    On Dec. 3, 1993, NCI announced that it would no longer recommend universal breast cancer screening for mammography beginning at age 40. The decision was based on the lack of clear scientific evidence for a reduction in deaths among women in their 40s, and the realization of the risks of screening, which had been noted by the NCI-sponsored International Workshop on Screening for Breast Cancer in February 1993.

    In December 1993, the leadership of NCI decided that the Institute would no longer make any universal recommendations regarding cancer screening. Instead, NCI would make available scientific evidence of the benefits and risks of screening. These would be designed to allow individuals to decide for themselves, in consultation with their health care provider, when to undergo screening. NCI's PDQ database includes statements of evidence on cancer screening for health professionals and the public, which are developed by a PDQ editorial board comprising experts from across the country.

  7. How will information about NCI's position be spread so women and doctors understand their options? Which organizations can women go to for information? Will there be a toll-free number to call?

    NCI will develop a mammography communications plan to reach a variety of audiences including concerned women, physicians and other health care providers, the mass media, policy makers, cancer-related organizations, and insurance providers. The plan will assist in communicating clear and understandable information concerning the benefits, limitations, and risks of screening mammography.

    To spread the message, NCI will use its established channels for information dissemination and access. These include the Cancer Information Service's telephone service (1-800-4- CANCER) and its outreach component; the PDQ database; the NCI World Wide Web site; and the Journal of the National Cancer Institute. New printed materials will be created and disseminated to bring the message to the mass media and the general public, and existing educational materials will be altered as needed. A general informational briefing will be held for members of Congress, along with targeted briefings for relevant congressional groups.

  8. If a woman in her 40s decides to have a mammogram, who pays?

    Payment depends on a woman's insurance coverage and where she lives. Medicare covers one mammogram screening every two years for its beneficiaries who are in their 40s and every year for women in their 40s with a personal or family history of breast cancer. Forty states plus the District of Columbia already require third-party payers to cover all or part of the cost of screening mammography for women in their 40s. An additional four states have legislation pending.

    Background on Breast Cancer and Mammography Screening

  9. What are the chances that an American woman might get breast cancer?

    As a woman ages, her chances of getting breast cancer increase. For example, present rates project that each year, out of 100,000 women

    • in their 40s, 163 will be diagnosed with breast cancer and 29 will die of it.
    • in their 50s, 263 will be diagnosed with breast cancer and 59 will die of it.
    • in their 60s, 374 will be diagnosed with breast cancer and 91 will die of it.

  10. What are the known risk factors for breast cancer?

    Age: The risk of breast cancer increases as a woman gets older. About 80 percent of breast cancers occur in women over the age of 50. The risk is especially high for women over age 60 and breast cancer is uncommon in women under age 35.

    Family History: The risk of getting breast cancer increases for a woman whose mother, sister, or daughter has had the disease. About 5 percent of women with breast cancer have a hereditary form of this disease, in which many family members may be effected.

    Personal History: Women who have had breast cancer may develop a second breast cancer.

    Other Risk Factors: Other risk factors include early menstruation (before age 12) and late menopause (after age 55), having a first child after age 30 or never having children. Risk is also increased moderately for women who have benign breast changes known as atypical hyperplasia. Current research is looking into the roles of obesity, hormone replacement therapy, diet, and alcohol use.

  11. What are the best methods of detecting tumors as early as possible?

    High-quality mammography with or without clinical breast exam is the most effective technology presently available to detect breast tumors.

  12. What are the benefits from mammography screening?

    Several studies have shown that regular mammography screening can decrease a woman's chance of dying from breast cancer. In addition, early detection may prevent the necessity of removing lymph nodes, undergoing radiation or chemotherapy, or removing a breast. The optimum age at which to begin mammography screening was one of the topics of the Consensus Development Conference.

  13. How does getting a mammogram affect survival in different age groups?

    Evidence about whether regular mammography can decrease a woman's chance of dying from breast cancer comes from eight large-scale screening trials where the number of women who died from breast cancer in the screened group was compared to the number who died in the group that was not screened.

    There is no convincing evidence that a woman under age 40 will benefit from regular mammograms. Two factors contribute to the lack of benefit in this age group -- the low incidence of breast cancer and the difficulty of "seeing" tumors with mammography in the relatively dense breasts of women younger than 40.

    For women between the ages of 50 and 69, there is strong evidence that screening with mammography on a regular basis reduces breast cancer mortality by about 30 percent.

    For women in their 40s, there is some recent evidence that screening with mammography on a regular basis may reduce breast cancer deaths by about 15 percent, but the evidence has not been as consistent or as strong as for women over age 50.

  14. If lives might be saved when women in their 40s receive regular mammograms, why is there any controversy? What are some of the limitations of mammography?

    • Detection does not always mean saving lives: Even though mammography can detect tumors as small as 1 centimeter (about 1/4 inch) in diameter, detecting a small tumor does not guarantee that a woman's life will be saved. Mammography may not help a woman with a fast-growing tumor that has already spread to distant parts of the body before being detected. In, addition, about 50 percent of women with mammography-detected breast cancer would not have died from breast cancer even if they had waited until a palpable lump appeared, because their tumors are slow growing and more treatable.

    • False Negatives: Because the breasts of younger women contain many glands and ligaments that appear dense on a mammogram, it is sometimes more difficult to spot tumors in the breasts of younger women. As women age, breast tissues become more fatty and tumors are more easily "seen" by mammography. Also, tumors tend to grow faster in younger women than in older women. They

      therefore appear more likely to grow between the scheduled mammograms. About 25 percent of breast tumors are missed in women in their 40s compared with 10 percent of tumors for women in their 50s.

    • False Positives: Between 5 percent and 10 percent of mammograms are abnormal. Of those in younger women that are followed up with additional testing, (another mammogram, fine needle aspiration, ultrasound, or biopsy) most will not be cancer.

    • Increased Cases of DCIS: Over the past 30 years, mammography has been able to detect a higher proportion of small tissue abnormalities called ductal carcinomas in situ (DCIS), abnormal cells confined to the milk ducts of the breast. (The number of DCIS cases increased from 742 to 4,676 from l983 to l993.) Some believe that many of these tumors are not life-threatening, while others think that some will eventually metastasize. Because there are few data to strongly support either view, these abnormalities are commonly removed surgically.

    • Limitation of Data From Trials: None of the large-scale screening trials included sufficient numbers of minority women or women at high risk for breast cancer to make strong statements about mammography effectiveness in such groups.

    • Radiation-Induced Cancer: Although it is theoretically possible that annual mammography may cause cumulative-radiation-induced breast cancer, particularly in women who are genetically susceptible to radiation exposure, there are no convincing data to support this hypothesis.

  15. What percentage of women in different age groups receive mammograms?

    • Of women ages 40-49, 59.9 percent received a mammogram in the past two years.
    • Of women ages 50-64, 65.1 percent received a mammogram in the past two years.
    • Of women 65 and over, 54.2 percent received a mammogram in the past two years.
      (1993 figures from National Center for Health Statistics.)

  16. What technologies other than mammography are under development for breast cancer screening?

    New imaging technologies under development for breast cancer screening include magnetic resonance imaging, breast ultrasound, and breast-specific positron emission tomography. In addition to imaging technologies, NCI-supported scientists are exploring methods to detect products of breast cancer in blood, urine, or nipple aspirates, and to detect genetic alterations that place women at increased risk for breast cancer.

  17. What research is NCI supporting to find better ways to prevent and treat breast cancer?

    Researchers are looking for ways to prevent breast cancer in women at high risk, including a large study 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 breast cancer prevention trial will serve as a model for future studies of cancer prevention. Studies of diet, nutrition, and environmental factors could also lead to preventive strategies.

    In the treatment arena, the challenge is to make treatment more targeted and effective, and less toxic. Scientists are studying high-dose chemotherapy with stem cell transplantation to determine if this therapy is effective. Biological therapies, such as the HER2/neu antibody, could be more effective and have milder side effects than other treatments.

    Many studies are also under way to identify the causes of breast cancer, including an analysis of the role that alterations in the BRCA1 and BRCA2 genes 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 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 are likely to develop and when.

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