Up to 30% of breast cancers are not identified by mammography
By adding tomosynthesis, a 3-dimensional (3-D) breast imaging technology, to standard digital mammography, radiologists’ diagnostic accuracy increases while false-positive recall rates decrease, according to the results of a multicenter study published in Radiology.
According to the National Cancer Institute, evidence exists showing that breast cancer mortality is reduced for women between the ages of 40 and 74 who receive mammography screening. However, mammography leaves as many as 30% of breast cancers undetected, and up to 10% of women who undergo a mammogram receive a false-positive recall.
With the new breast tomosynthesis screening technology, multiple, low-dose images are captured from different angles around the breast. Then a 3-D reconstruction of the breast is produced using the images. Both digital mammography and breast tomosynthesis (approved by the FDA in February 2011) can be quickly performed in sequence on the same mammography equipment.
“This is the first major advance in breast imaging and breast cancer screening since the development of breast MRI,” said lead researcher Elizabeth A. Rafferty, MD, director of Breast Imaging at the Avon Comprehensive Breast Center at Massachusetts General Hospital in Boston. “The beauty of tomosynthesis is that it addresses 2 major concerns with screening mammography: missed cancers and false-positive rates."
The study involved 1192 women recruited from 5 sites; 997 had complete data sets. A standard digital mammogram followed by breast tomosynthesis was performed on each of the women. The combined procedure had a total radiation dose less than 3 mGy, which is the FDA limit for a single mammogram.
Rafferty and colleagues then conducted 2 reader studies involving 312 and 310 eligible cases, respectively. A total of 48 cancers and 12 radiologists were included in the first reader study; 51 cancers and 15 radiologists in the second.
Study results showed that using standard mammogram and tomosynthesis resulted in increased diagnostic accuracy for all 27 radiologists. The combined exam increased diagnostic sensitivity by 10.7% for radiologists in reader study 1 and 16% for radiologists in reader study 2.
“Almost all of the gains in diagnostic sensitivity with the combined modality were attributable to the improved detection and characterization of invasive cancers, which are the cancers we are most concerned about because of their potential to metastasize,” Rafferty said.
The combination of breast tomosynthesis and standard digital mammography also significantly decreased false-positive recall rates among the 27 radiologists. Reader studies 1 and 2 saw absolute recall rate reductions of 38.6% and 17.1%, respectively.
“In the clinical setting, we would expect that type of reduction in recall rate to translate into a substantial number of unnecessary diagnostic tests being avoided,” Rafferty said.
Source: NCI.