Q&A: Why more info can lead some women to prefer delaying first mammogram

The messaging around mammography often doesn’t go beyond this simple three-word refrain: screening saves lives. Medical groups have also moved toward earlier breast cancer screening: The United States Preventive Services Task Force, for example, earlier this year recommended that all women begin screening mammography at age 40.

And yet, more women prefer to wait until age 50 to begin screening after learning about breast cancer screening’s benefits and drawbacks, according to a study published in the Annals of Internal Medicine on Monday. “When women were informed about the benefits and downsides, more women wanted to wait until they’re older. The ones who wanted to wait until 50 went from 8.5% to 18%,” said Laura Scherer, a social psychologist at the University of Colorado School of Medicine and lead author on the study.

That may seem odd until you dive deeper into the reasons people gave for their preference. Women who wanted to wait until they were 50 tended to have lower risk of breast cancer, based on things like family history, and vice versa.

“They had rational, logical reasons for their preferences,” Scherer said. “Women who wanted to screen earlier, they had higher risk, like a family history, and were less concerned about the downsides.”

The downsides of screening are at the center of the enduring argument around just how much breast cancer screening is too much screening. Although mammography saves lives, it also comes with a certain risk of false positives, unnecessary biopsies, and overdiagnosis. That’s when screening finds certain early-stage cancers that paradoxically wouldn’t have harmed individuals during their lifetime, but the treatment for these cancers carries some burden.

All cancer screening policies try to balance these potential harms with the benefits of early detection or prevention of cancer. In Scherer’s study, about 500 women between the ages of 39 and 49 first answered questions about their screening preferences and then were shown a decision aid, or some pertinent information about the pros and cons of breast cancer screening, before being asked the survey questions again.

Some of that information included statistical modeling results like “out of 1,000 women screened from age 40-49, 239 experience a false positive result… out of 1,000 women screened from age 50–59, 220 experience a false positive result.” Similarly, the decision aid also pointed out that starting screening at age 40 would save an additional life out of 1,000, although it didn’t communicate other benefits of early detection like less intensive treatment. Women were also given a personal breast cancer risk score based on the National Cancer Institute’s personal risk calculator.

Notably, Scherer ran this study before the United States Preventive Services Task Force updated its guidance to recommend people begin screening mammography at age 40.

STAT spoke with Scherer about the survey, its results, and what they suggest about the way breast cancer screening is communicated. This interview has been edited for length and clarity.

What were the reasons that people gave for deciding to delay or not to delay screening after the decision aid?

We asked them to tell us in an open-ended question, what was the most important reason for the preference you told us about? Women who wanted to delay were less concerned about cancer risk. They had less risk on average, and they were more concerned about overdiagnosis and false positives. Whereas the women who wanted to screen at their current age were at higher risk. On average, they worried about a family history of cancer, and they weren’t as concerned about the downsides.

Other research has shown that some women want to delay screening after receiving evidence about mammograms. But one thing that was surprising — there was no increase in the number of women who never wanted a mammogram at all. About 5% of women said that was their preference.

I’m a social psychologist by training. We think about people’s judgment-making and biases and show a lot of research that people aren’t always rational. But this research shows people show a good understanding of the information, and how it makes sense to them personally, and make pretty logical judgments as a result.

What do you think of the contrast with the fact that medical societies have been tending to recommend people begin screening earlier?

I think doctors like to make decisions that make sense from a population standpoint, and people like to make decisions for themselves that incorporate their personal risk. They’re considering the information with different goals. There are loud voices calling for more screening, screening at lower ages, but I don’t think that necessarily reflects the perspectives of informed women who are considering and reflecting on how the data apply to them personally.

But one important piece of context is that most insurance is required to pay for preventive care that the USPSTF gives an A or B recommendation for. The recent change from the prior C to now a B recommendation for screening at 40 increases access to screening, especially for low-income people. This is important because the majority of women showed they did still want to start screening under 50.

There’s a lot of work to find ways to provide people with personalized screening recommendations. Looking at your findings, does it look as though people are trying to provide that to themselves once they learn more about breast cancer screening?

We are giving women information, and they’re intuitively doing what we’re trying to find evidence for doing — which is find personalized screening recommendations. I think this study is very promising for the future of personalized screening, showing there’s an appetite for that. But we need the data first. We can’t make real personalized screening recommendations until we know for sure, with some confidence, that we’ll be minimizing harms and maximizing benefits for people. That’s really the goal though.

Trials are working on this. The WISDOM trial, for example, and the results have the potential to be very important.

One key finding was that nearly half of the women surveyed found the information to be surprising or unfamiliar. What do you make of that?

We did find a lot of people said the information was conflicting with what they heard before. The thing they found the most surprising is overdiagnosis. Overdiagnosis is difficult to communicate and counterintuitive. What’s more surprising is the proportion of women who really hadn’t heard this information at all. A lot of women get the message they just should screen, and they aren’t exposed to the evidence.

As long as women are informed and making a decision based on that evidence, that’s fundamentally a good thing. I worry that people are exposed to information that’s not true, and they’re turned off to screening because of false information.

What do you think is missing from the messaging around breast cancer screening?

The USPSTF has written forcefully that people have the right to be informed about preventive care. I think that’s also true about mammograms. We have historically messaged simply about mammograms, and said, “go get screened; it saves lives.” It definitely does. But it also has drawbacks that some people, not everybody, care about.

So, there is an ethical imperative to provide balanced information about mammograms. We know from this study that it will not deter people from screening altogether. My question is, what’s the alternative? We don’t inform people of the drawbacks of screening, and a potential ramification is that they may find out about it from other means and wonder why they’ve never been told before. I worry that fundamentally can foster distrust.