Mammograms are great, but they are not perfect. We still don't see about 20 percent of breast cancers with standard screening mammograms, and they still sometimes lead to well-intentioned but unnecessary operations (removing or biopsying things that end up being benign). Also, more broadly, in light of disputes as to how many lives mammograms actually save, we're always looking to improve.
The FDA recently approved breast tomosynthesis, known more coolly as "3-D mammography." It involves having an X-ray source move around one's breast, and multiple planes being reconstructed to create a digital 3-D image. Doctors can then look at it from every angle, as opposed to the two planar X-rays obtained in standard "2-D" mammograms. As in the above image, 3-D also lets doctors isolate thin planes of tissue in the breast, to see exactly where a concerning area is -- and if it might just be the result of overlapping areas of normal tissue. That can be tough to tell on 2-D.
It sounds good, but the most convincing evidence in favor of its widespread use didn't come into play until this week. In a study of 1192 patients at Masschusetts General Hospital -- published this week in the journal Radiology -- 3-D mammograms, when used in addition to 2-D, improved diagnostic accuracy by about 7 percent. That's big. They also led to 26 percent fewer false positives (where we detect something, but it turns out to be nothing). That means less undue worry and fewer unnecessary further testing.