BBreast density is a known risk factor for developing breast cancer, but that well-accepted research finding stems from studies done in women younger than 75. That makes sense because breast density decreases with age, but cancer epidemiologist Dejana Braithwaite of the University of Florida Cancer Control and Population Sciences Program wondered about older women: How much does the density decrease and how much could it be? to import?
In an analysis of more than 220,000 mammograms published Thursday in JAMA Oncology, her team reports that the density and risk of breast cancer are not disappearing.
Braithwaite spoke to STAT about that research and her hope to learn more about cancer in older women. This interview has been condensed and lightly edited for clarity.
What were you hoping to learn?
While it is generally accepted that screening tests for women up to age 75 are appropriate, what is less clear is what happens after women turn 75 and whether screening still makes sense. What we really want to do is generate the evidence to inform custom detection strategies. For some women, it may make sense to continue screening after age 75, beyond what the guidelines recommend if they are in good health and perhaps have some risk factors such as breast density. But for some women who may have some health problems, they may not benefit from screening.
What is the connection between breast density and cancer?
One of the really common risk factors for breast cancer is the density of the breasts, and that is a measure of the amount of fibers or glandular tissue (dense tissue) compared to fatty tissue. Higher density has been associated with an increased risk of invasive breast cancer.
And for older women?
Ours is one of the first studies to actually look at older women, particularly women aged 75 and over. Although the prevalence of density decreases with age, about half of women ages 40 to 64 have dense breasts, and we found that by the time women reach their 60s and 70s, about 30% to 32% still have dense breasts. And we found that their breast density is associated with an increased risk of invasive breast cancer in the two groups of women we studied: 65 to 74 years and 75 and older.
Was it unexpected?
It is surprising that 30% of these women still have dense breasts, perhaps a little more than we expected. After menopause, it drops, but 30% is still a considerable number. Given the associations we’ve seen in younger women that density leads to an increased risk of breast cancer, that finding isn’t surprising. It is biologically plausible.
How do you imagine your job could affect the care women receive or the decisions they make about continuing to have screening mammograms?
We believe that breast density should be included in prediction models that aim to estimate breast cancer risk and consider it alongside life expectancy to make informed decisions about the potential benefits versus harms of continuous screening. We are currently developing an intervention targeting women and primary care physicians to provide a personalized risk assessment tool to help guide conversations about screening after age 75.
When does detection still make sense?
Between the ages of 75 and 80, some women who have a good life expectancy of at least 10 years can still benefit from continuous mammography. In reality, it’s more that after age 80, fewer women are likely to live another 10 years to really benefit. But there is a general consensus that for any type of cancer screening, if you have a life expectancy of 10 years, there is a high chance that you will benefit from cancer screening.
This year, screening recommendations for lung and colorectal cancer has started at a younger age. His work suggests extending it to the other end of life.
Yes, the questions are somewhat similar, you know, when to start and then when to discontinue and how often to examine. In addition to breast cancer screening, I also have a grant that focuses on lung cancer screening. And the guiding principle of our work is really to develop the evidence that can be translated into interventions to facilitate risk-based screening. What we mean by that is really individualizing cancer screening based on the characteristics of the patient and, in general, how to maximize the benefits and minimize the harms.