There are two primary implications of mammographic breast density. One implication is the effect on mammographic sensitivity (i.e., the test's ability to identify a clinically-occult malignancy) - this concept is known as masking. The second implication is the increase in breast cancer risk imparted by dense breasts. Both these implications are described below. Overall, the potential masking effect of breast density is likely of greater import than the minor increase in breast cancer risk.