A new study has found that 40 percent of women who get mammograms have dense breast tissue, and the results of those examinations can be very hard to decipher — and as a result, many women mistakenly think they’ve been diagnosed with breast cancer.

Because 20 percent of the population reads at an 8th grade level, the mammogram results for those who have dense breasts — which make it harder to detect traces of cancer — are difficult to understand, and thus many think they have gotten cancer when they haven’t, according to a Boston University Medical Center statement.

Dense breast tissue means more connective and fibrous tissue than usual, which both mean there is a higher risk of breast cancer and that it will be harder for a mammogram to spot that breast cancer.

The findings are based on notification letters sent in 23 states. These letters often used complex language that would take a college degree to understand. Letters sent out in some states required a postgraduate degree level to decipher them.

“We found widespread discordance between states’ DBN readability and corresponding basic literacy levels,” the statement said, quoting lead author Nancy Kressin, PhD, director of the Health and Healthcare Disparities Research Program in the section of general internal medicine in the department of medicine at BUSM and Boston Medical Center.

A New York Times report indicates that just 12 percent of American adults have proficient health literacy, and 26 states have passed laws requiring mammography testing facilities to inform women if they have dense breast tissue as part of the results.

The notification results are complex, but they may need to be in order to create a useful discussion between patient and doctor, the report noted.