National Cancer Advisory Board Issues Mammography Screening Recommendations

Members of the National Cancer Advisory Board (NCAB) concurred 17 to 1 in recommending that the National Cancer Institute (NCI) advise women 40 to 49 to get screening mammograms every one to two years if they are at average risk for breast cancer. For women 50 years and older, the Board said NCI should recommend mammograms every one to two years.

The NCAB said that women who are at higher than average risk should seek expert medical advice about beginning mammography before age 40 and about their screening frequency when they are in their 40s.

The Board defined higher risk women as those who have had breast cancer; women carrying identified genetic alterations that may make them more susceptible to breast cancer; women in families in which multiple family members are affected with breast cancer, generally at younger ages; those with breast disease that may predispose them to cancer or those having had two or more breast biopsies for benign disease; women with 75 percent or more dense breast tissue on previous mammograms that made mammography reading difficult; or women having a first birth at age 30 or older. Women without these risk factors are considered to be at average risk of developing breast cancer.

Because of the limitations of mammography, the Board stated that a clinical breast examination by a health care provider is an important part of regular, routine health care for women.

The Board stated that health insurers, including managed care organizations, should pay for mammography for higher risk women at any age and for all women beginning at 40.

"The Board concluded that there is enough evidence to support a woman's decision to begin screening in her 40s," said Barbara Rimer, Dr. P.H., board chair, professor and director of cancer prevention, detection, and control research at Duke University, Durham, N.C.

"But the Board also wanted women and their providers to be informed fully about both the benefits and limitations of mammography so they can make informed decisions," Rimer added.

The NCI decided in 1993 not to recommend universal mammography screening beginning at age 40 because at that time there was not clear scientific evidence that women in their 40s undergoing regular screening have a reduced risk of dying of breast cancer. For many years, the evidence for women age 50 and older has shown clear benefit.

In reaching its conclusions, the National Cancer Advisory Board, a presidentially appointed committee that advises and consults with the director of the NCI, considered updated findings from breast cancer screening studies presented in January at an National Institutes of Health Consensus Development Conference. These new data show that regular screening mammography of average risk women in their 40s reduces deaths from breast cancer by about 17 percent.

In addition to the benefits of screening, the Board outlined the limitations of mammography. In particular, it referred to the high percentage (compared to women over age 50) of abnormal mammograms that are not cancer, but require further testing -- another mammogram, fine needle aspiration, ultrasound, or biopsy. Estimates are that a women who has a yearly mammogram in her 40s has about a 30 percent chance of having a "false-positive" mammogram.

Another limitation of mammography for women in their 40s is the difficulty of detecting tumors in the denser breasts of younger women. About 25 percent of breast tumors are missed in women in their 40s compared with 10 percent of tumors for women in their 50s.

Research is under way in imaging technology such as magnetic resonance imaging, breast ultrasound, and breast-specific positron emission tomography to overcome these limitations.

In addition to imaging technologies, NCI-supported scientists are exploring methods to detect traces of breast cancer in blood, urine, or nipple aspirates, and to detect genetic alterations in women who are at increased risk for breast cancer.

NCAB also recommended that the NCI take the following actions:

• Develop, in partnership with other professional and advocacy organizations innovative methods of educating women, physicians, and other providers regarding the benefits and limitations of mammography as well as the risk factors for breast cancer.
• Create a uniform database that will encourage all investigators conducting large-scale randomized screening studies for women ages 40 to 49 to provide primary data for combined analyses.
• Convene an independent Mammography Data Monitoring Board to review on an ongoing basis the data from randomized mammography trials and, to report regularly to the NCAB and the public on the progress of the trials.

See also: List of National Cancer Advisory Board Members