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UVM study finds declining breast cancer screening rates for at-risk women

A woman is positioned for a traditional mammogram at Tufts Medical Center in Boston.
Bizuayehu Tesfaye
A woman is positioned for a traditional mammogram at Tufts Medical Center in Boston.

Back in 2009, a panel of independent health care experts changed its guidelines on breast cancer screenings to recommend that women begin getting routine mammograms at age 50, instead of 40.

The U.S. Preventive Services Task Force also noted “insufficient evidence” for screening women aged 75 and older.

Flash forward to today — a recent study from the University of Vermont Cancer Center finds that at-risk women across America are getting far fewer mammograms than they did 15 years ago…

The study also found that Vermont has seen the second largest decline of any state in the union.

To learn more, Vermont Public’s Jenn Jarecki spoke with one of the paper’s co-authors, Dr. Sarah Nowak. Their conversation below has been edited and condensed for clarity.

Jenn Jarecki: Can you take us back to 2009, and the reasons behind changing the suggested breast cancer screening age from 40 to 50, and to cite insufficient evidence for women 75 and older?

A woman poses for the camera.
Andy Duback
University of Vermont Cancer Center
Dr. Sarah Nowak

Dr. Sarah Nowak: Sure. So the U.S Preventive Services Task Force issues guidelines about routine preventive health care services. And they periodically review their recommendations, taking into account new evidence.

So in 2009, they reviewed the evidence about both the benefits of breast cancer screening as well as the harms of breast cancer screening. So the main harms of breast cancer screening that they consider are overdiagnosis. So that's diagnosis of a cancer that wouldn't have become clinically apparent without screening. So somebody wouldn't have even known that they would have had cancer — it wouldn't have caused a problem.

And the other harm of screening is false positives. So a false positive is when you have an abnormal mammography result that leads to follow-up testing, including potentially biopsy, which can cause a lot of unnecessary worry — and just a lot of unnecessary health care sort of down the line. So they looked at the evidence about the rates of benefits and the rates of these harms for women in the different age groups, and that's what led them to issue the revised guidelines.

Will you share your findings on the potential unintended consequences of changing those guidelines, in terms of screening rates of at-risk groups of Vermont women?

So what we expected to see was declines in screening for women in their 40s and for women ages 75 and older. But what we also found were declines in screening rates for women ages 50 to 74. And we found that those declines were correlated with the declines in screening for women in their 40s, and women ages 75 and older.

And so the fact that these trends in all three age groups seem to be moving together led us to conclude that it might be the changes in the guidelines, and the fact that the rates are declining in the younger and older age groups that are causing declines also in the middle age group. And when we looked at the rates of decline, we found that the rate of decline for women ages 50 to 74 was the second largest in Vermont of any of the states.

I understand there was some pushback when the U.S Preventive Services Taskforce changed its guidelines in 2009. Sarah, will you walk us through how you and your colleague, Dr. Brian Sprague, came about doing this research?

So I had been really interested in the pushback previously, and had done some work on looking at what factors encourage women to want to be screened, and might have led to some of the pushback and the demand for screening. And one of the important factors is that when a woman knows somebody personally who is diagnosed with early stage breast cancer through screening —that's a very powerful motivator for her to be screened herself. And then one of the conclusions from that is that women know other women in all age groups. And so if you have declines in screening for women in their 40s and women ages 75 and older, we sort of hypothesize that there could be a spillover effect and declines in screening for women ages 50 to 74.

And I presented some of the work that led to this hypothesis, and Dr. Sprague said, "Well actually we're seeing declines in screening for women ages 50 to 74." With Vermont mammography registry data, he saw that several years ago. And so the fact that Vermont was kind of a leader in the declines for breast cancer screening made us realize that it's possible that this could be happening in other parts of the country as well — which is what caused us to look at the national data.

Sticking with Vermont for a moment, can you contextualize for us how many women we're talking about with this decline in screening rates?

Yeah, our estimate is about 10,000 women ages 50 to 74 — so 10,000 fewer women being screened in that age group [over a 10-year period].

At the risk of asking an obvious question, what are the consequences of lower breast cancer screening rates for at-risk women in that 50 to 74 range?

Well, we know that appropriate breast cancer screening can be life saving. So increased breast cancer mortality is a potential consequence, as well as requiring more aggressive treatment.

Though it appears these declining screening rates for at-risk women are tied to the change in national guidelines, your team doesn't know exactly why the spillover is happening. What's next in terms of researching this phenomenon?

That's right. So we want to dig in a little bit more, because if it is due to the changes in guidelines, there are several mechanisms that could be leading to the change — even if it is tied to the guidelines more broadly. So I mentioned one, which is kind of this person-to-person social network effect of just knowing fewer women diagnosed early with breast cancer.

Another possibility is just that the guidelines themselves lead to more awareness of the downsides of screening for everybody, which could lead women in that 50- to 74-year-old age group to be a little bit more concerned for themselves about the downsides of screening.

And then we want to just also look and see if there are other factors that could be leading to these kinds of declines. If there are changes in mammography screening capacity or primary care capacity at state levels that are leading to these declines.

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