For some time now, obesity has been associated with an increased risk of breast cancer. It’s well established that obese, postmenopausal women have an increased risk of breast cancer compared with postmenopausal women of normal weight. Part of the problem is that obese women are diagnosed at a later stage, perhaps because those with larger breasts may be less able to feel small lumps.

Now new research in the Archives of Internal Medicine looked at whether obese women are at a disadvantage with mammography readings, which may be another reason that breast cancers are diagnosed at a later, more advanced stage in this population.
The study indeed finds women who are overweight have a higher chance of having a mammogram that is erroneous, but with a twist. It’s commonly thought that mammograms are easier to read when the breasts are larger, because the fatty tissue in the breast gives a better background so that a cancer can stand out. This study shows, it’s not a matter of missing a cancer--it’s a matter of finding suspicious spots that amount to nothing serious.
The study’s results were not what experts would have expected. Dr. Otis Brawley, a medical oncologist at Emory University in Atlanta, says, “I’m surprised. The mammogram is showing us images that we think might be cancer. And we’re more likely to think that a fat woman obese woman has cancer and therefore we need to do a biopsy.”
Dr. Joshua Gross, chief of breast imaging at Beth Israel Medical Center in New York, agrees. “From looking at mammograms for many years women who have large breasts and are very fatty are easier to read and easier to find small things.”
Overweight women had a 14% increased risk while obese women had a 20% increased chance of recall over normal weight women. “Maybe women were recalled because the tissue was inadequately compressed because of the size and the machine couldn’t handle it,” says Dr. Gross.
The findings are not insignificant. Each false positive mammogram because of obesity costs the system an extra $600, resulting in a multimillion dollar burden on the health system annually. “Anything that involves recalls is not good for the system. The patient has to be re-registered, seen again, filmed again and interpreted again. You’re doubling the work of a mammogram, ” remarks Dr. Gross.
Dr. Brawley believes it’s a sign of the imperfection of mammograms in general. “Mammography is not a perfect science. We need to realize that we need to get better diagnostic and better screening technologies.”
It is possible bigger X-ray plates to make better images could be created. The researchers also say they need to do more studies on looking at how to adequately compress the breasts during the mammogram to get the best images. They believe what needs to be done is research into the accuracy of other imaging techniques like MRI and ultrasound, in obese women. For now, the mammogram error issue is yet another cost to the healthcare system caused by the increased incidence of obesity in America.

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