Following on from our theme of roads and getting places, I’d like to take you on a world tour highlighting several research papers that have studied the importance of breast density. In line with other research, these studies further emphasize the risks that women with dense breasts—approximately 40% of women in Western screening populations—face when compared to women with non-dense breasts:
- 2–6X more likely to get breast cancer
- Double the rate of interval breast cancers
- Lower mammographic sensitivity
- Higher recall rates and biopsy rates
- 10% larger tumor size for screen-detected cancers
- 6% more women with lymph-node-positive disease
Let’s start our world tour in Norway, where Dr. Solveig Hofvind (New study confirms higher cancer rate in women with dense breast tissue – Radiology) and her colleagues used data from Oslo’s Cancer Registry of Norway collected over an eight-year period and including 307,015 digital screening examinations and over 107,000 women ages 50 to 69. Their research found that women with dense breasts were more likely to get breast cancer compared to women with non-dense breasts, (6.7 vs. 5.5 women per 1,000 examinations), and had higher rates of interval breast cancer (2.8 vs. 1.2 per 1000 examinations), a 10% larger tumor size for screen-detected cancers (mean 16.6 mm vs. 15.1 mm), and more lymph-node-positive disease (24% of women vs. 18% of women).
We will now make a stop in the United States, where Dr. Karla Kerlikowske and Dr. Celine Vachon from UCSF and the Mayo Clinic, respectively, demonstrated that using automated breast density evaluation was equivalent to the subjective evaluation of the radiologist, albeit more reproducible, in terms of predicting interval and screen-detected breast cancer risk (Computers equal radiologists in assessing breast density and associated breast cancer risk – Annals of Internal Medicine). The study concluded that women with “extremely dense breasts had a 5.65 times higher risk of interval cancer and a 1.43 times higher risk of screen-detected cancer than women with scattered fibroglandular densities.”
Finally, our tour takes us to Sweden, where between 2011 and 2013 mammograms from women attending screening at four Swedish hospitals were evaluated to understand the risk of developing breast cancer. The Karolinska Mammography Project for Risk Prediction of Breast Cancer (KARMA) showed a strong link between volumetric breast density measurements, lifestyle factors (e.g., physical activity and alcohol consumption), novel genetic loci [2015, 2018], and breast cancer risk.
I hope this was an informative journey into the research being done globally to improve outcomes in breast cancer.
