(Reuters Health) - Post-mammogram form letters telling women about dense breasts may be more confusing than helpful if they are difficult to read and understand, researchers say.

Thirty U.S. states require providers to send letters to patients explaining that so-called dense breasts - which have more breast tissue and less fat - make mammograms harder to read, which increases chances that a cancer could be missed. Having dense breasts also raises the risk of developing breast cancer, the study team notes in Journal of the American College of Radiology.

When the researchers evaluated the text of these letters, though, they found that most used language more complex than the eighth-grade reading level recommended by many medical organizations.

“Patients with dense breasts may not be aware that increased density is a risk factor for breast cancer or that it can make it more difficult to catch small cancers on mammograms,” said lead study author Dr. Ami Saraiya of the Rhode Island Hospital’s Department of Diagnostic Imaging in Providence.

About half of women are found to have dense breast tissue in mammography screenings. In the past decade, 10 states have started to require that all women who have a mammogram receive a letter explaining what breast density is, and that women with dense breasts might want to consider extra screening, such as an ultrasound or MRI to confirm their mammogram results. Twenty states require letters only for women whose mammograms show they have dense breasts.

“These letters are important, though some may be written at a higher reading level than others,” Saraiya told Reuters Health by email. “If you receive a letter, it is important to discuss this with your healthcare provider.”

The researchers evaluated the readability of letters in the states where they’re required, looking at factors such as sentence length, word length and syllables. For states with a law in place in 2016, the researchers looked at whether the letters’ readability had changed by 2018.

To compare publicly-available information about breast density, researchers also measured the readability levels of seven top websites that discussed dense breasts, including breastcancer.org, densebreastinfo.org, and the Susan G. Komen Foundation site.

Overall, every mandated letter exceeded the sixth-grade reading level recommended by the U.S. Department of Health and Human Services. Connecticut’s letter had the most difficult language, equivalent to a college-level text. Alabama and New York letters had the easiest text, equivalent to a seventh-grade reading level.

Only eight states had letters at the eighth-grade reading level recommended by the Centers for Disease Control and Prevention, the National Institutes of Health and the American Medical Association. Of the states with letters in 2016, the readability level remained about the same, except for Missouri, which dropped from college-level to eighth grade.

The online resources ranged from sixth- to eleventh-grade reading levels, with the American Cancer Society text meeting the sixth-grade guideline, and the American College of Radiology text at a seventh-grade level.

“For some women, this is the first way they learn about breast density, and it can generate fear and confusion,” said Christine Gunn, a researcher with the Boston University schools of medicine and public health, who wasn’t involved in the study.

“Some women mistake them to mean they have cancer, and the medical community needs to make sure we address these unintended consequences,” Gunn said in a phone interview.

Notification letters could be improved by including pictures, figures and links for patients to reference, the study authors note. Letters should also be tailored for different languages and cultural identities.

“Some states have complied with the law in a way that doesn’t provide useful information and may even raise more questions for women,” said Dr. Jennifer Haas of the Harvard T.H. Chan School of Public Health in Boston, who wasn’t involved in the study.

“Density is just one risk factor,” she said in a phone interview. “We should use different formats such as pictures and videos to tailor information for women based on their different risk factors.”

SOURCE: bit.ly/2E8SGxu Journal of the American College of Radiology, online January 24, 2019.