Well, first let me tell you that dense breast tissue is considered a sign of youth. That's right: Dense breasts are thought of as youthful breasts. This density, however, can make finding abnormalities in the breast difficult, since dense areas show up as white on a mammogram, and tumors also happen to be white. Ugh.

A new concern has arisen, though. A study recently published in Current Biology says that the cells making up dense breast tissue may actually be more fertile ground for breast cancers to grow in. The findings suggest a possible cellular mechanism linking human breast tissue density with tumor aggressiveness. This was a surprise to me since the only correlation in the past has been that density makes it harder to detect breast cancers early.

So now it appears that women with increased breast density on mammograms are at increased risk for breast cancer for two reasons: Their cancers are harder to spot on screening, and dense breast tissue may encourage the growth of breast cancers that are more invasive than average. Yikes.

So what do you do if this describes your breasts? First, get a digital mammogram. Digital technology can see abnormalities within dense breasts much more clearly and dependably than can regular mammograms. Second, if appropriate, your radiologist may also recommend that your breasts be examined with magnetic resonance imaging (MRI). MRIs, however, are not a substitute for mammography; they would only be done in addition to the mammogram.

This may also explain why women taking hormone replacement therapy (HRT) have a higher risk of breast cancer—HRT increases density!