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Scientists study what women know — and don’t know — about breast density and cancer risk

Breast density is a risk factor for cancer, but until now, no study has asked women what they actually know about breast density in relation to screening that they have had. A new three-state-wide study out of Dartmouth’s Norris Cotton Cancer Center reveals varying knowledge on the topic

In the United States, a number of states have notification laws which compel a radiologist to inform a woman if she has dense breasts and the significance of her dense breasts. However in practice, these state laws vary. In a new qualitative study, a team of scientists at Dartmouth and Dartmouth-Hitchcock’s Norris Cotton Cancer Center and the Breast Cancer Surveillance Consortium led by Dr. Karen Schifferdecker and Dr. Anna Tosteson, sought to explore women’s knowledge and perceptions of breast density and experiences of breast cancer screening across three states with and without notification laws.

The recently published focus group study (Schifferdecker KE et al. Knowledge and Perception of Breast Density, Screening Mammography, and Supplemental Screening: in Search of “Informed” Journal of General Internal Medicine (2019)) found that women from all states had varying knowledge about their own breast density and breast density in general. A number of women were aware of the difficulty of detecting cancer with dense breasts, but only one woman knew that density actually increased breast cancer risk. “We found that very few women received information about breast density during healthcare visits although some were encouraged to get supplemental imaging or to pay for new types of mammography such as breast tomosynthesis,” says Schifferdecker. “Women who were offered more imaging or different technology usually thought these were ‘better,’ even though they were given little information about the effectiveness or harms.”

The study also found, importantly, that women from all states expressed a strong desire for more information about breast density. “The findings in this paper are exciting because no research on dense breasts has explored women’s knowledge and experiences in their own words and compared this across different states,” says Schifferdecker. “We partnered with the national Breast Cancer Surveillance Consortium to identify and recruit women who had a recent screening and also had dense breasts. In this way, we knew all women had dense breasts and could explore what they knew or did not know, including their own personal breast density.

The conclusions also identify opportunities for improvements in educating women so they may make informed decisions related to mammography and supplemental screening. “Women want–and deserve–more usable information about breast cancer risk” says Schifferdecker. “More research needs to be done to understand how the medical community can better assist women in making informed decisions related to breast density and screening.”