Obese Women at Risk for False Mammogram Result

Findings from a new study indicate that obese women are at increased risk for having their mammograms read as abnormal when, in fact, everything is okay, according to a report in the Archives of Internal Medicine.

Dr. Joann G. Elmore, at the University of Washington School of Medicine, Seattle, and her colleagues point out in their paper that obese women are at higher risk for breast cancer and tend to be diagnosed at later stages of the disease compared with other women. But what role mammogram results play in these differences is not clear. Elmore’s group analyzed data for more than 100,000 screening mammograms performed on nearly 68,000 women age 40 or older. Obese women were more likely than their non-obese peers to have normal mammogram results initially misread as abnormal. In medical parlance, this is known as a “false positive” result. The authors attribute the difference to poor image clarity because of thicker volume of breast tissue compressed in the mammogram machine, additional images required to adequately cover the entire breast in each X-ray, and increased search area that radiologists have to review. This difference in false-positive rates “is extremely important at a population level,” Elmore’s group maintains, resulting in higher costs and greater anxiety among patients. They suggest that losing weight could improve screening mammography performance. But until or unless that happens, obese patients should still be encouraged to undergo mammography, they write, despite the risk of a false positive result. “To reduce the potential for anxiety,” the investigators add, “obese women should be informed of the increased likelihood that they may need additional imaging or other diagnostic procedures following their screening mammograms.” (Source: Archives of Internal Medicine: Reuters health News: May 2004.)