Abstract
The biological concept of bilateral symmetry as a marker of developmental stability and
good health is well established. Although most individuals deviate slightly from perfect
symmetry, humans are essentially considered bilaterally symmetrical. Consequently,
increased fluctuating asymmetry of paired structures could be an indicator of disease.
There are several published studies linking bilateral breast size asymmetry with increased
breast cancer risk. These studies were based on radiologists’ manual measurements of
breast size from mammographic images. We aim to develop a computerized technique to
assess fluctuating breast volume asymmetry in screening mammograms and investigate
whether it correlates with the presence of breast cancer. Using a large database of
screening mammograms with known ground truth we applied automated breast region
segmentation and automated breast size measurements in CC and MLO views using three
well established methods. All three methods confirmed that indeed patients with breast
cancer have statistically significantly higher fluctuating asymmetry of their breast
volumes. However, statistically significant difference between patients with cancer and
benign lesions was observed only for the MLO views. The study suggests that automated
assessment of global bilateral asymmetry could serve as a breast cancer risk biomarker
for women undergoing mammographic screening. Such biomarker could be used to alert
radiologists or computer-assisted detection (CAD) systems to exercise increased
vigilance if higher than normal cancer risk is suspected.
