TUESDAY, Sept. 17, 2002 (HealthDayNews) -- When it comes to reading routine mammograms, young, unseasoned radiologists are more likely than older, experienced ones to be suspicious of lumps that later prove benign, a new study has found.
The study, appearing in tomorrow's Journal of the National Cancer Institute, showed that women who have their screening mammograms read by greener doctors have about a 50 percent higher chance of being told they might have breast cancer than if they see a veteran. While these "false-positive" readings may result from an abundance of caution, they're emotionally jarring, have a steep financial toll, and often lead to painful biopsies.
"There's definitely a high degree of variability among radiologists in how they interpret mammograms," said Dr. Joann Elmore, a University of Washington physician and lead author of the study.
"The best doctors probably get the most challenging patients, and you need to adjust for that," Elmore said. And many doctors quick to call a lump suspicious probably end up catching cancers that other doctors might let pass.
Still, she said, the findings indicate that women face sizable differences in false-positive rates among doctors in their communities, and that could have an impact on the care they receive. "In this case experience might be even more important, because we're talking about a screening test where you're trying to do no harm."
Annual X-ray mammograms are recommended for women over the age of 40 -- meaning tens of millions of the tests are performed each year in this country. Roughly 190,000 women are diagnosed with breast cancer every year.
In their study, Elmore and her colleagues looked at how consistently two dozen New England radiologists read 8,734 routine mammograms taken from nearly 2,170 middle-aged and elderly women.
False-positive rates ranged from 2.6 percent to nearly 16 percent, the researchers found. Doctors in practice longer were less likely to misread a test than those trained recently.
Breast cancer appears in roughly one in 1,000 women. Therefore, a woman called back for further study by a radiologist with a false-positive rate of 10 percent is about 100 times more likely be cancer-free than to truly have a tumor.
When Elmore's group accounted for factors that might exacerbate the gulf -- like the difficulty of patients seen, for example, or how many films the doctor read -- the amount of variability shrank by about half. But enough remained that if a woman were to see two radiologists in her town, her chances of being told she had a tumor were 50 percent higher at the less accurate office.
The tests were performed between 1985 and 1993, before radiologists adopted a standardized five-point scale for mammography. So the situation today might be somewhat more even than in decades past, Elmore said.
Elmore said the study doesn't address diagnostic mammography, and she suspects that the variability between physicians in these cases is much narrower. In diagnostic imaging, the volume of tests is much lower.
M. Robyn Andersen, a health psychologist at the Fred Hutchinson Cancer Center in Seattle and a co-author of an editorial accompanying the journal article, said the study highlights a fact of mammography women don't want to hear: It's not a perfect test.
"Many may not know just how many false-positives happen for every cancer found," Andersen said. "If you're called back, the chances are very good that it is indeed a false-positive, so that's not the time to get worried. Get worried at the needle biopsy. Before that it's probably a conservative radiologist trying to do their job."
One way to iron out the variability would be to have two radiologists read each screening film, as is done in many countries outside the United States. Andersen said she's not sure why the United States doesn't use this safety net.
"My guess is it's basically a culture thing," she said. "A lot of physicians and a lot of us as people who go to physicians are really used to believing that any physician we see is more than just competent. They're always right. They don't usually think of second opinions for routine tests." The reality, though, is that reading mammograms is an art, and different doctors have different eyes.
What To Do
For more information on mammography quality, try the Food and Drug Administration. For more on the value of the test, visit the Department of Health and Human Services.
