Study: Breast Screening in U.S. Needs Work
Cancer detection rates the same in U.K. with fewer biopsies, false positives
TUESDAY, Oct. 21, 2003 (HealthDayNews) -- Women in the United States are twice as likely as women in the United Kingdom to get called back for further testing after a routine mammogram. And the Americans undergo two to three times more open surgical biopsies than the British do.
Those are the major findings of a new study that also shows breast cancer detection rates in the United States are no better than those in the United Kingdom.
Over a 10-year period of getting regular mammograms, the researchers say, 40 percent to 50 percent of American women can expect a false-positive scare, while just 15 percent of British women will be called back for what turns out not to be cancer.
"We recall twice as many women who don't have breast cancer," says study author Dr. Rebecca Smith-Bindman, an assistant professor of radiology, epidemiology and biostatistics at the University of California at San Francisco. The work appears in the Oct. 22/29 issue of the Journal of the American Medical Association.
"We do two to three times the number of open surgical biopsies and we're not getting anything back in terms of cancer detection," she adds.
"We need to figure out how to recall fewer women" without compromising the cancer detection rate, she says.
While technological progress in mammography has been good, she adds, "we haven't really focused on interpretation."
To arrive at these conclusions, Smith-Bindman and her colleagues evaluated the records of women age 50 and older who underwent 5.5 million mammograms from 1996 to 1999 within three large-scale mammography registries, or screening programs -- two in the United States and the National Health Service Breast Screening Program in the United Kingdom. Within 12 months of the screening, more than 27,000 women were diagnosed with breast cancer among the three groups.
Among women who were 50 to 54 and got a first screening mammogram, nearly 15 percent in one U.S. program and 12.5 percent in the other were recalled, but only 7.6 percent in the U.K. program were. But breast cancer detection rates per 1,000 mammograms were similar -- 5.8 and 5.9 in the U.S. programs and 6.3 in the U.K. program.
While women recalled in both countries underwent a similar number of biopsies, U.S. women were more likely to undergo open surgical biopsy, a more complicated procedure than fine needle aspiration or core biopsy, another alternative.
While several other studies have suggested these differences between the countries, "this is the first head-to-head comparison on a very large scale," Smith-Bindman says.
Fear of malpractice may drive the recall rate in the United States, she says. Another driving force might be that U.K. radiologists typically read more mammograms -- they are required to read at least 5,000 annually, while U.S. doctors must read only 480 a year. Double readings of mammograms are common in Britain but not in the United States.
"I think the results are interesting," says Robert Smith, director of cancer screening for the American Cancer Society. Part of the discrepancy between the two countries, he agrees, is that British radiologists simply perform more mammograms.
"There have been studies that have shown those who read 2,500 to 3,000 mammograms a year are more accurate," he says. In the United States, many radiologists probably read about 1,000 a year, Smith estimates.
To rectify the situation, having very specific performance guidelines might help, Smith-Bindman says, adding "doctors in the U.K. are evaluated annually."
And, in the United Kingdom, when open surgical biopsy rates increased, the National Health Service set a goal of reducing them without compromising the detection rate and succeeded, she says.
Women are advised to have mammographies done at a center that specializes if possible, Smith advises, or at a center that does many mammograms, reasoning that the more mammograms a radiologist reads, the more proficient he or she will become.