On the surface, that doesn't seem like an earth-shattering story. Guidelines are routinely revised and updated based on available evidence. But the new recommendations go against entrenched medical practice and advice, and the firestorm the change caused shows no signs of flickering out, and is pitting two government groups against each other.
The American Cancer Society's standard for breast cancer screening for the average woman in good health is to get yearly mammograms starting at age 40 and breast self-exam is an option for women starting in their 20s. In 2002, the U.S. Preventive Task Force recommended mammograms every one to two years starting at age 40, and that evidence was insufficient to teach women how to conduct self-exams. A little different, but nothing drastic separated the two. Until now.
The USPTF commissioned two studies, according to the article published in the Annals of Internal Medicine: 1) a targeted systematic evidence review of 6 selected questions relating to benefits and harms of screening, and 2) a decision analysis that used population modeling techniques to compare the expected health outcomes and resource requirements of starting and ending mammography screening at different ages and using annual versus biennial screening intervals.
They concluded that for the average woman, risk of breast cancer is very low in women age 40 to 50 and that the risk of false positives and complications from biopsies and other invasive procedures is too high for the procedure to be used routinely. Translation: you don't need to get a mammogram until 50, not 40, and you only need it once every two years. Also, they recommend against teaching women how to do breast self-exams.
The change in recommendation is in itself a huge deal, but even more so is the potential downstream implication: insurance companies routinely use USPTF to guide coverage.
Let's go through the background, recommendations, and weigh the pros/cons.
Background
Widespread use of screening, along with treatment advances in recent years, have been credited with significant reductions in breast cancer mortality, the authors write in the Annals article. The estimated lifetime risk for a woman to develop breast cancer is 12% overall, but increases as you age and if you have certain risk factors, like certain genetic mutations or a history of breast cancer in your family. Estimates ranging from 17% to 25% of deaths from breast cancer (not cases, but deaths) occur in women in that younger-than-50 age group - the tumors are usually more aggressive, invasive and deadly.
Good, bad and the ugly
Starting screening at age 40 prevents one additional breast cancer death per 1,000 women getting mammograms. As you go up in age, that ratio changes - you'd save 1 woman per 1,300 women 50 to 59 years old screened, and 1 for 377 for women 60 to 69 years old.
But screening before 50 would result in roughly 500 of the 1,000 women getting false positive results at least once, and 33 of them getting unnecessary biopsies, according to an excellent article in Forbes.
That's a huge issue, which I've covered here and here. In their desire to treat before a lump can do any harm, doctors may actually (unintentionally) cause harm. Extra radiation, psychological stress, possible side effects from biopsies, surgery and treatment - the benefits do not outweigh the risks, the USPTF said. Another consideration is that you could find a lump, but it wouldn't be something that would cause the woman harm, so you'll unnecessarily treat her.
Another good article from the LA Times notes that women tend to overestimate the risks of dying from breast cancer.
The risk that a 40-year-old woman will die of breast cancer in the next 10 years is very small -- just 0.19%, according to data from the National Cancer Institute. (Over her entire lifetime, the risk is 2.86%.) And the risk that a woman of 40 will be diagnosed with invasive breast cancer before her 50th birthday is 1.44%. Most women vastly overestimate these risks, research shows.But, say critics of the new recommendations, screening benefits outweigh the harms - a life saved is a life saved, and women whose cancer is detected later because of changed screening recommendations will have a poorer prognosis. Plus, assuming women will be harmed psychologically by false positives is just that - making an assumption.
Meanwhile, the chance of "false positive" results (which appear to signal cancer but turn out to be incorrect) is 60% higher in women in their 40s than in women in their 50s, in part because younger women's breasts are denser and harder to evaluate. Rates of over-diagnosis -- the detection of lesions that would never become cancerous -- can run as high as 10%, the analysis said.
Recommendations
The USPTF looked at all of these issues and more in depth, without consideration of cost or policy, and are recommending the following:
- The USPTF recommends against routine screening mammography in women aged 40 to 49 years. The decision to start regular, biennial screening mammography before the age of 50 years should be an individual one and take into account patient context, including the
patient's values regarding specific benefits and harms. (Grade C recommendation) - The USPTF recommends biennial screening mammography for women between the ages of 50 and 74 years. (Grade B recommendation)
- The USPTF concludes that the current evidence is insufficient to assess the additional benefits and harms of screening mammography in women 75 years or older. (I statement)
- The USPTF concludes that the current evidence is insufficient to assess the additional benefits and harms of clinical breast examination beyond screening mammography in women 40 years or older. (I statement)
- The USPTF recommends against clinicians teaching women how to perform breast self-examination. (Grade D recommendation)
- The USPTF concludes that the current evidence is insufficient to assess additional benefits and harms of either digital mammography or magnetic resonance imaging instead of film mammography as screening modalities for breast cancer. (I statement)
You'll note that all are followed by a grade; see here for a description of what these grades mean. The USPTF also has these handy summary charts for film mammography here and for other screening methods here.
So far, insurance companies have said they won't restrict coverage based on these recommendations, since they are for women in general and the need for screening will differ from patient to patient.
To be clear...
The USPTF is not saying, "don't be screened," said Diana Petitti, a doctor and preventive medicine expert at ASU and vice chair of the USPSTF, in Forbes. "'It is about saying, consider the tradeoffs and decide explicitly at which age to be screened.' While some women may decide to get mammograms earlier than 50, she says, they should talk about the pros and cons first with their doctor and not just have it done automatically."
These recommendations are for the average woman in good health, not a woman with increased risk for developing breast cancer. You can do a risk assessment online here (for women over 35), but just because you have a risk factor doesn't automatically mean you'll develop breast cancer. Gender (female), age (older), genetic mutations (e.g. BRCA), family history of breast cancer (double the risk if mother/sister/daughter have it, 5-fold if two of these have it), personal history (3-4 fold risk if you have it in one breast of getting it in the same or other breast), ethnicity (white = more cases, black = higher risk of death) and dense breast tissue all affect your risk of developing breast cancer. You can't do anything about these risk factors, but there are some you can try to manage, according to the ACS.
But in the end it all boils down to the individual patient, the USPTF says. "'The task force isn't saying there isn't a benefit' to screening women in their 40s, but 'we're saying the benefit is small,'" Dr. Petitti said in the WSJ. "The change really is a change between do it routinely and don't do it routinely."
"We're saying there needs to be a discussion between women and their doctors."
More coverage
ABC News here
NPR here
WSJ here
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