A new study says there are significant differences in mammogram readings

From Medical Correspondent Dr. Steve Salvatore

NEW YORK (CNN) -- Mammograms have proven to be essential for the screening of breast cancer. But a new study finds there can be a significant difference of opinion when it comes to reading a radiologic picture of the breast.

The study in the Journal of the National Cancer Institute finds radiologists can interpret mammograms differently and don't always agree on what they find.

"There was a substantial agreement between the radiologists' reading if cancer wasn't there," said Dr. Karla Kerlikowske of the San Francisco VA Medical Center. "But if cancer was there, there was only moderate agreement saying whether there was a breast abnormality or not."

Researchers say some mammograms are more difficult to read than others.

"The more dense a woman's breasts were, the more variability there was in the mammographic interpretation," Kerlikowske said.

When radiologists read mammograms, they use a classification system called BI-RADS to help describe what they see.

"The BI-RADS system was developed in order to have a common language among radiologists to describe the findings on mammograms so that one radiologist can understand what the other is describing," said Dr. Thomas Kolb of Columbia Presbyterian Medical Center.

But according to researchers, even with the BI-RADS system, radiologists still disagreed -- partly because the reading of mammograms is subjective.

"The radiologists' perception of what is really an abnormality and what isn't an abnormality varies quite a bit between radiologists," Kerlikowske said.

To get an accurate reading, breast cancer specialists recommend seeking out a radiologist who specializes in reading mammograms. They suggest looking for someone who reads a minimum of 10 mammograms a day or about 1,000 mammograms a year.

Experts also recommend asking questions. There may be a follow-up test that can help clarify the mammogram.

If a mammogram is difficult to read, a patient may want to consider a second opinion.