Dense breasts, those that have a lot of bright or white areas seen in a mammogram, have been known to be at higher risk for breast cancer for some time, prompting 19 U.S. states to require health providers to tell women whether or not they have dense breasts after a mammogram. Should a woman with dense breasts automatically get extra screening? Some laws suggest it, but according to a study, this might not be the best solution.

Published in the journal Annals of Internal Medicine, the study created models calculating the cost and possible additional life years gained by including sonography in breast cancer tests. Researchers found out that when all women with dense breasts between 50 and 74 years old got sonograms after coming up clean on standard mammograms, costs spiked considerably but only marginal benefits to health are attained.

Say, 3,000 dense-breasted women got additional sonograms. Only one death related to breast cancer will be prevented given the magnitude of effort placed into getting additional screening. Bump that number up to 10,000 women getting supplemental screening and only three to four deaths will be prevented while 3,500 healthy women will be subjected to needless biopsies.

Not to mention that sonograms frequently produce false positives, driving many women to put themselves at the risk, inconvenience and cost of undergoing a breast biopsy when they either don't have breast cancer at all or have a form of cancer that is not life-threatening.

"Not everybody with dense breasts is going to get cancer. There are people with dense breasts that are not at high risk," said Dr. Karla Kerlikowske from the University of California, San Francisco and a co-author for the study.

This is because dense tissues in breasts are mostly made up of connective and milk-producing tissues. They, however, appear white in mammograms like potential cancer spots so they are automatically treated with concern.

For the researchers, more than just relying on the presence of dense breasts, a woman's overall breast cancer risk level must be taken into consideration to determine whether or not additional screening will be needed. Aside from dense breasts, age and close relation to someone with breast cancer are other risk factors.

Even when dense breasts are present, when other risk factors or symptoms are not, the American College of Obstetricians and Gynecologists does not recommend additional testing for women.

Breast density has the tendency to drop with age so risk levels may change over time.