The U.S. Preventive Services Task Force (USPSTF), a group of experts charged by the government to review important health advice, created an uproar in 2009 when it released a draft of its report advising women to start getting mammograms at age 50, rather than at age 40 as most cancer experts, including the American Cancer Society, had been suggesting. The USPSTF also concluded that the screening should happen every two years, instead of yearly.
Now, in its final recommendation, published Monday in the Annals of Internal Medicine, the task force is standing by this advice—but it has taken pains to carefully reword its recommendation to reduce confusion. “If you have great science but communicate it poorly, you get what happened in 2009, where there was a complete misunderstanding,” says Dr. David Grossman, vice chair of the USPSTF and senior investigator at Group Health Research Institute in Seattle, Wash. “We recognize that mammography is an important tool in preventing deaths from breast cancer, but that the value of mammography does vary by age.”
The final version stresses that the benefits of mammography increase gradually with age. The recommendation says that the ability of routine mammograms to lower the risk of breast cancer begins at age 40, but that they significantly increase around age 50. The balance between these benefits and the risks of false positives and over-diagnosis or overtreatment tips in favor of screening as a woman ages.
“I fear that with our previous recommendation, it sounded like it was either/or: start mammogram screening at age 40 [as other groups advised] or wait until age 50. We tried to clarify that both the risks of breast cancer and the benefits of mammography change over time, so there is not an abrupt shift at a particular age,” says Dr. Michael LeFevre, immediate past chair of the USPSTF and professor of community medicine at University of Missouri School of Medicine.
What sets the USPSTF recommendation apart is its message that the harms of screening must be balanced against the benefits. Until the task force’s recommendation, the risks of screening often weren’t part of discussions women have with their doctors about mammograms. For decades, the need to educate people about screening and the risks of cancer meant that mammograms — and other cancer screens — tended to be presented in an almost exclusively positive light and as a mandate for anyone interested in improving their health.
“The mentality was that, 'Look, we have tests that can reduce your chance of dying of cancer, so you should be getting screened,'” says Dr. Therese Bevers, medical director of the cancer prevention center at MD Anderson Cancer Center who is not a member of the USPSTF. “We didn’t understand there were costs. The harms were not on the horizon; we didn’t understand we would be getting false positives and over diagnoses and things like that. That was something we learned as we were doing screening.”
That education is now prompting a rethinking of the culture of screening that has pushed regular screening tests as the most responsible way to protect yourself from cancer, and even from dying an early death.
Does Screening Save Lives?
The problem is, as a recent study pointed out, there is no solid evidence supporting the fact that cancer screening “saves lives” as many campaigns, particularly early on, claimed. Yes, regular screening can, theoretically, detect cancer earlier and therefore potentially reduce the risk of dying of cancer, but there’s no scientific proof that it can reduce your risk of dying early from any cause.
Yet public health experts have been making a leap from the fact that screening can lower the risk of dying from, say, breast cancer, to assuming that it can help a woman to live longer and avoid dying prematurely of any other cause. “I am very willing to admit that [it’s] a surrogate, and that it’s not a perfect surrogate [for saving lives],” says Dr. Otis Brawley, chief medical officer of the American Cancer Society says of the data supporting only reduction of cancer deaths and not overall early deaths. “I actually try to avoid using the phrase ‘saving lives’ in almost everything I write and do.”
But ask the average woman about what cancer screening is supposed to do, and she will probably say "save lives." It might seem like a small distinction but it’s important. Looking at overall mortality, or deaths from any cause, is the most accurate way to measure the effectiveness of screening. Just looking at screening’s effect on cancer deaths, or death rates from a specific cancer, says nothing about how long that person will live overall, since it only looks at one disease. In addition, it does not take into account any complications or side effects of the screening, including exposure to radiation and even overtreatment, that could also potentially be fatal.
MORE: Mammograms Go 3-D
Prostate cancer provides a perfect example. When prostate cancer screening became de rigeur in the 1990s, doctors didn’t realize that most of the lesions they would find would not actually need treatment. Studies now suggest that about half of men diagnosed with prostate cancer are over diagnosed, meaning they received treatment for a cancer that likely would not have ever progressed to cause symptoms or contribute to their early death. These men likely had lesions that grew so slowly that men were more likely to die of something other than prostate cancer. But many received hormone treatments since they believed that getting a diagnosis of prostate cancer meant they needed to treat it somehow, even if they didn’t have any symptoms.
That led to an increase in heart disease rates from the exposure to the well-intentioned but unneeded anti-androgen hormone therapy — and the USPSTF to recommend that men skip getting the blood test to screen for prostate cancer entirely. “The definition of what cancer is has moved from the 1953 definition where all cancer that was diagnosed killed people, to the 21st century definition where we now realize that a 10mm lesion in a woman’s breast may be genomically programmed to grow and spread and kill her, or it may be genomically programmed to just stay 10mm for the next 70 years in this 60 year old woman,” says Brawley.
More Room for Choice
Ultimately, the new mammogram advice makes more room for choice. “Some women will say, 'I’m happy to have a mammogram every other year beginning at age 50,'” says MD Anderson's Bevers. “Others will say, 'I don’t care if I get false positive results, I want to start screening at 40.'”
When women go in for their first mammograms the rates of false positives tend to be high, simply because “these are the first several mammograms where we are learning what their breasts look like,” says Bevers. “We might see asymmetry, or something different, and we call her back for a suspicious finding that becomes a false positive. It may simply be a characteristic of her breasts, but we don’t know that, because we’ve never imaged her breasts before.”
Brawley says that mammogram screening advice is slowly but surely becoming more sophisticated, and the USPSTF’s recommendation, as well as the ACS’s recent revision, reflect this evolution. It’s a move away from the paternalism that characterized medicine for so long, where doctors decreed what patients, or even healthy people should do to avoid serious illness, to a more precision medicine-based strategy that empowers people to educate themselves and work with their doctors in making health decisions that fit their needs and their circumstances. “The patient needs to be involved in this discussion, and needs to make decisions about her fate,” he says. If she’s armed with the information about the benefits and risks associated with mammograms, she can hopefully start to do that with more confidence.