The Food and Drug Administration is proposing a rule for breast cancer screenings that would require doctors to give women more information about the risks associated with dense breasts.

The agency wants doctors to ensure patients understand how dense breasts, which don't have a lot of fatty tissue, can skew the accuracy of mammograms and present a higher risk of developing breast cancer later in life. About 12 percent of all women are diagnosed with breast cancer at some point in their life, the FDA said, citing data from the National Cancer Institute.

"Given that more than half of women over the age of 40 in the U.S. have dense breasts, helping to ensure patient access to information about the impact that breast density and other factors can have on the risk for developing breast cancer is an important part of a comprehensive breast health strategy," FDA Principal Deputy Commissioner Amy Abernethy said in a statement Wednesday.

Mammograms are considered the best way to detect breast cancer. However, they're not as reliable in dense breasts, characterized as those with not as much fat and more fibrous or glandular tissue, according to the American Cancer Society. Dense tissue makes it harder for doctors to see cancer, meaning the tests can be less accurate.

"Mammograms of dense breasts ... can be difficult to interpret because the dense tissue can obscure signs of breast cancer and lower the sensitivity of the image," the FDA said. "Dense breasts have also been identified as a risk factor for developing breast cancer."

The FDA is proposing specific language to explain how density may skew the results and to encourage women to talk to their doctor about how this relates to cancer risk and their individual situation.

The agency also wants to tighten its regulation of mammography facilities, including with the ability to notify patients that testing did not meet the FDA's quality standards. The rule will be open for public comments for the next 90 days.

"We're certainly imposing additional and stronger requirements on these facilities," the FDA's Dr. Jeff Shuren told reporters on a conference call Wednesday "We think this is important to protect the public health and best serve patients."

Currently, 37 states require some sort of notification to women with dense breasts, according advocacy group DenseBreast-Info. If implemented, the FDA's language would set the national standard, though states could pursue more stringent requirements, said Shuren, the agency's director of the Center for Devices and Radiological Health.

He outlined the specific language that women with dense breasts would receive:

"Mammography is the best screening test to search for breast cancer, but it does not find all breast cancers. Some patients have high breast tissue density, more glands than fat in the breasts, which makes it harder to find breast cancer on a mammogram. Your breast tissue density is high. Some patients with high breast density may need other imaging tests in addition to mammograms. Follow the recommendations in this letter and talk to your health care provider about high breast density and how it relates to breast cancer risk and your individual situation."

"Generally, we're really pleased to see the FDA has taken the important step to empower women to make informed decisions about their health," said Caroline Powers, director of federal relations at the American Cancer Society Cancer Action Network.

Powers said the group has pushed the FDA on the issue for several years. Regardless of momentum at the state level, the organization wanted a federal standard to make sure women around the country were receiving the same information.