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More Mammogram Results Questioned in U.S. Compared to U.K. (dateline January 15, 2004)


A recent study finds that more mammograms performed in the United States are labeled as suspicious or uncertain by U.S. radiologists than by radiologists in the United Kingdom. This, in turn, leads to more unnecessary surgical breast biopsies in the United States, according to the study results. There are several possible reasons for the higher number of recalled mammograms in the United States, including fear of malpractice in the U.S. and more specialization among radiologists in the U.K.

Mammography is a special type of x-ray imaging used to create detailed images of the breast. Research has shown that the early detection of small breast cancers by screening mammography greatly improves a woman's chances for successful treatment. In the United States, the National Cancer Institute recommends that all women 40 to 50 years of age receive mammograms every one to two years and all women 50 years of age and older receive yearly mammograms.

In a study published in the October 22, 2003 issue of the Journal of the American Medical Association, Rebecca Smith-Bindman, MD, of the Department of Radiology at the University of California–San Francisco and her colleagues identified women aged 50 years or older who underwent 5.5 million mammograms from January 1, 1996, to December 31, 1999, within 3 large-scale mammography registries or screening programs: the Breast Cancer Surveillance Consortium and National Breast and Cervical Cancer Early Detection Program in the United States, and the National Health Service Breast Screening Program in the United Kingdom. total of 27 612 women were diagnosed with breast cancer within 12 months of screening among the 3 groups.

The results of the study showed that recall rates (i.e., the rate of women who were called back for additional testing based on interpretation of their mammogram) were approximately twice as high in the United States than in the United Kingdom despite an approximately equal number of cancer diagnoses among these women. A total of 14.4% of women between the ages of 50 to 54 who underwent their first mammogram in the U.S. were called back for additional testing compared to only 7.6% of women who underwent mammography in the United Kingdom. Additional testing included surgical breast biopsies.

A higher mammography recall rate despite an equal number of cancer diagnoses signals that many U.S. radiologists are referring women for unnecessary additional testing. Dr. Smith-Bindman and her colleagues recommend that efforts to improve U.S. mammographic screening include lowering the recall rate without reducing the cancer detection rate. This could be accomplished by setting better standards for mammographic interpretation and holding radiologists to these standards, according to Dr. Smith-Bindman.

One reason for the higher mammography recall rate in the U.S. is no doubt the elevated fear of malpractice among radiologists if they interpret a positive mammogram as normal. Referring patients for additional testing increases the chances breast cancer will be detected accurately.

Furthermore, in the United Kingdom, more radiologists specialize in breast imaging compared to in the United States. In the U.S., it is not uncommon for general radiologists to read mammograms as well as many other types of x-rays. According to Dr. Smith-Bindman, in the U.K., breast imaging radiologists each read approximately 7,000 mammograms annually compared to 1,000 each in the U.S.

However, experts point out that more early cases of breast cancer are diagnosed in the United States compared to in the U.K. The earlier breast cancer is detected, the greater the patient’s chances for successful treatment and survival.

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