Compare new and prior mammograms, doctors urge
NEW YORK (Reuters Health) - Comparing a mammogram with previously obtained images greatly enhances the accuracy of evaluation, Dutch researchers report.
"In mammography screening," Dr. Antonius A. J. Roelofs told Reuters Health, "viewing current mammograms in association with prior mammograms ... may decrease the number of false alarms by as much as 44 percent."
Although such comparisons are made routinely with film-based screening, the transition to digital technology presents a number of problems in continuing the practice, Roelofs of Radboud University Nijmegen Medical Center and colleagues note in the journal Radiology.
To investigate how important viewing prior mammograms might be, twelve experienced screening radiologists used digital displays to read 160 screening mammograms twice -- once with and once without prior mammograms. Eighty of the mammograms were obtained from women who were later diagnosed with breast cancer, while the other 80 mammograms were from women with normal or benign results.
"When only positive cases were considered, no difference was observed," Roelofs' group reports. However, the number of possible lesions that proved to be non-lesions was reduced by 44 percent when prior screening mammograms were available.
A compromise approach was also tested, in which the reading radiologists asked for a prior film only when they felt it might be helpful. Roelofs said this strategy "appeared to reduce the large beneficial effect of prior mammograms significantly."
He said this "shows that radiologists cannot reliably predict for which current mammograms the prior mammograms are necessary," and concluded the study "proves the importance of prior mammograms in the reading process."
SOURCE: Radiology, January 2007.
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Compare new and prior mammograms, doctors urge
Breast self-exam and screening mammograms are two of the best tools available to diagnose breast cancer early, when it's most treatable. Still, mammograms aren't perfect. Mammograms can identify an abnormality that looks like a cancer, but turns out to be normal. This "false alarm" is called a false positive. False positives usually require more testing, and sometimes a biopsy.
The study reviewed here found that when a radiologist compares the most recent mammogram with earlier mammograms, false positives can be reduced by 44%. The key was to ALWAYS compare current and earlier mammograms, instead of comparing mammograms only when the radiologist thinks it might help. Comparing mammograms also can help radiologists identify problem areas that might otherwise be missed, but this study didn't address that issue.
The shift from film mammograms to digital mammograms may make it difficult for radiologists to compare mammograms, at least for a little while. But in time digital mammography should make it easier for earlier mammograms to be available for comparison. This is because the images are stored electronically on a computer (rather than on film) and could be retrieved anytime and anywhere.
What can you do to decrease the risk of a false positive? Speak up. When you get your mammogram, tell the technician or radiologist that you want to be sure the images are compared with earlier mammograms. If you're getting your mammogram in a different place than before, talk to the staff to make sure they have access to your earlier images. When you get your results, ask whether they were compared with your earlier mammograms. If there was no comparison, talk to your doctor to make sure it's done.
The National Digital Medical Archive has a service called myNDMA. This service allows women to electronically save digital medical images, including digital mammograms, in a secure place. The images can be made available, with your permission, for retrieval and review by doctors.