Many women underestimate breast density as a risk factor for breast cancer

 

Many women underestimate breast density as a risk factor for breast cancer

 

Dense breast tissue has been associated with up to a four times higher risk of breast cancer. However, a new study suggests that few women view breast density as a significant risk factor.   The study surveyed 1,858 women ages 40 to 76 from 2019 to 2020 who reported having recently undergone mammography, had no history of breast cancer and had heard of breast density.   Women were asked to compare the risk of breast density to five other breast cancer 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.   “When compared to other known and perhaps more well-known breast cancer risks, women did not perceive breast density as significant of a risk,” said Laura Beidler, an author of the study and researcher at the Dartmouth Institute for Health Policy and Clinical Practice.   For example, the authors report that dense breast tissue is associated with a 1.2 to four times higher risk of breast cancer compared with a two times higher risk associated with having a first-degree relative with breast cancer – but 93% of women said breast density was a lesser risk.   Dense breasts are made up of more glandular and fibrous tissue than fatty tissue. The finding is common, happening in about half of women undergoing mammograms.   Breast density changes over a woman’s lifetime and is generally higher in women who are younger, have a lower body weight, are pregnant or breastfeeding, or are taking hormone replacement therapy.   The level of breast cancer risk increases with the degree of breast density, but experts aren’t certain why.   “One hypothesis has been that women who have more dense breast tissue also have higher, greater levels of estrogen, circulating estrogen, which contributes to both the breast density and to the risk of developing breast cancer,” said Dr. Harold Burstein, a breast oncologist at the Dana-Farber Cancer Institute who was not involved in the study. “Another hypothesis is that there’s something about the tissue itself, making it more dense, that somehow predisposes to the development of breast cancer. We don’t really know which one explains the observation.”