Scientists Find Mammography is Still "Gold Standard" for Breast Cancer Detection but Recommend Research into More Accurate Methods (dateline March 14, 2001)
|In a comprehensive review of breast
cancer detection methods, a committee of scientists report that standard film mammography is still the best available method to detect
breast cancer. Mammography helps detect approximately 85% of all breast cancers and has
contributed to a 2% annual decline in breast cancer deaths in the past 10 years. Despite
the overall effectiveness of mammography, the scientists acknowledge that mammography can
miss breast cancer in a small percentage of women or falsely indicate cancer in others,
leading to unnecessary breast biopsies. Therefore, the
committee recommends that further research investigate better methods of breast cancer
detection. At the same time, underprivileged women should be given better access to
existing breast cancer screening technology.
"With all its limitations, film mammography remains the gold standard against which new imaging technologies will be measured," said Joyce C. Lashof, MD, FACP, in an Institute of Medicine/National Academy of Sciences news release. "To date, no quantum leap has been made in this area. At the same time, many of the newer tools offer certain advantages and deserve to be studied further," said Dr. Lashof, who chaired the Committee on Technologies for Early Detection of Breast Cancer. The report was released by the U.S. Institute of Medicine and National Research Council of the National Academies in March 2001.
According to the report, no technology is 100% accurate in detecting all breast cancers or abnormalities. In fact, using several different technologies is often the best way to detect breast cancer. While mammography is currently the only exam approved by the U.S. Food and Drug Administration (FDA) to screen for breast cancer in women with no signs of the disease, other technologies (such as ultrasound or magnetic resonance imaging, MRI) may be useful in further investigating abnormalities detected with mammography.
However, the scientists also expressed concern that technologies approved as diagnostic breast exams may not be effective screening tools. They recommended that the FDA base their approval and coverage of new screening technologies on scientific data gathered from clinical trials and that these trials be organized in conjunction with the appropriate federal agencies and breast cancer organizations. Additionally, the National Cancer Institute (NCI) should sponsor clinical trials every 10 to 15 years to re-evaluate the effectiveness of existing technologies, such as mammography. Because the U.S. population is rapidly aging, the NCI should also investigate whether mammography screening would be beneficial to women over age 70.
In the meantime, women should be given greater access to mammography to help screen for breast cancer. Currently, the Centers for Disease Control and Preventions (CDC) Breast and Cervical Cancer Prevention and Treatment Act provides free mammograms and Pap smears to approximately 15% of financially underprivileged women. However, the scientists recommend setting the goal of reaching 70% of these women. Former President Clinton also signed a bill last October 2000 that requires Medicare to cover the cost of treatment for women diagnosed with breast or cervical cancer as a result of the government screening program.
While mammography is currently the most effective method of detecting technology, the committee did acknowledge that mammography has its limitations. For instance, mammography can miss up to 15% of breast cancers, especially in young women with dense breasts (density shows up as white regions on mammogram films and can eclipse cancer). Furthermore, while mammography can detect many early-stage breast cancers, some fast-growing cancers may not be visible on a mammogram film when they are still small enough to be treated effectively.
Conversely, the number of breast abnormalities and cancers detected in women has risen significantly since routine mammography was implemented. The scientists admit that the early detection of abnormalities will be problematic until there is a better understanding of the biology and genetics of these abnormalities. Until physicians are able to distinguish between those abnormalities that will progress to invasive cancer (and require treatment) and those which will never become a threat (and thus do not require treatment), breast cancer screening will contribute to an inevitable overdiagnosis and overtreatment of some breast abnormalities. At the same time, the committee emphasizes that improved detection methods and treatment advances have helped to reduce the number of deaths from breast cancer in the last decade.
Until more improved screening methods exist, women should follow the American Cancer Societys guidelines to help detect breast cancer early when the chances for successful treatment and survival are the greatest:
Younger women with a family or personal history of breast cancer should talk to their physicians about beginning annual mammograms before age 40.