A new study, published in JAMA Network Open and involving researchers from Dartmouth’s Geisel School of Medicine and Boston University (BU), finds that many women underestimate the importance of breast density as a risk factor for breast cancer.
Breast density refers to breasts that contain more glandular and fibrous tissue than fatty tissue and is a normal condition that is present in roughly half of women who undergo mammograms.
Breast density is associated with a 1.2 to four times higher risk of breast cancer compared to, for example, a two times higher risk associated with having a first-degree relative with breast cancer. Other risk factors include obesity, alcohol consumption, not bearing children, and having a prior breast biopsy. High breast density can also make it harder to find cancer on mammograms.
“Despite the widespread adoption of breast density notification laws in recent years, which have now gone into effect in 38 states, little is understood about how women perceive the overall impact of breast density on their breast cancer risk and what they know about reducing their risk,” explains Christine Gunn, PhD, an assistant professor of The Dartmouth Institute for Health Policy and Clinical Practice, a faculty member of Dartmouth Cancer Center.
Gunn served as a co-investigator on the study, collaborating with first author and Dartmouth colleague Laura Beidler, MPH, and BU colleagues Nancy Kressin, PhD, Jolie Wormwood, PhD, Tracy Battaglia, MD, MPH, and Priscilla Slanetz, MD, MPH.
The researchers conducted a national survey over a two-year period (2019 to 2020) with 1,858 women (ages 40 to 76), asking them to compare the breast cancer risk associated with breast density with five other risk factors—having a first-degree relative with breast cancer, being overweight or obese, drinking more than one alcoholic beverage per day, never having children, and having a prior breast biopsy.
The study team also did follow-up qualitative interviews with a smaller number of women (between February and May 2020) who reported being notified of their breast density, asking them what they thought contributes to breast cancer and how they could reduce their risk.
“One of the key takeaways was that women, far and away, saw family history as the most important risk factor for developing breast cancer,” says Gunn. “In contrast, few women perceived breast density as a risk factor. And those that did minimized it compared to family history, even though breast density is a lot closer to family history in terms of relative risk than some of the other risk factors.”
Another significant finding was that fully a third of the participants in the qualitative arm of the study thought that there weren’t any actions they could take to reduce their risk of developing breast cancer. “In reality, there are things women can do to lower their risks, from reducing their alcohol intake to eating a healthy diet to taking medications if they are at the highest risk,” Gunn says.
“I think what our findings tell us is that more comprehensive education about breast cancer risks and prevention strategies are needed for both patients and their doctors,” she says. “If a national mandate requiring women to be notified about breast density goes into effect, we’re hoping it will create more opportunities for things like risk assessment tools to be used, so that women can have a better understanding of their risk.”
The Dartmouth Institute for Health Policy and Clinical Practice is a world leader in studying and advancing models for disruptive change in healthcare delivery. The work of Dartmouth Institute faculty and researchers includes developing the concept of shared decision-making between patients and healthcare professionals, creating the model for Accountable Care Organizations (ACOs), and introducing the game-changing concept that more healthcare is not necessarily better care.