The government's independent panel of preventive health experts has now recommended that women in their 40s not automatically be screened for breast cancer using mammography. But will—and should—women listen? Today's announcement by the U.S. Preventive Services Task Force, historically conservative in its recommendations, puts it at odds with plenty of other organizations, including the American Cancer Society, the American College of Obstetricians and Gynecologists, and breast cancer advocacy and information groups such as Susan G. Komen for the Cure and Breastcancer.org.
The notion of screening 40-something women at normal risk of developing the disease has long been controversial, or at least complicated. The American College of Physicians, for example, in 2007 changed its own policy and warned that mammograms in younger women at low risk of breast cancer may do more harm than good. For example, it can expose them to needless follow-up testing, the organization said.
For many women, the USPSTF's updated recommendations are likely to be confusing. The new guidelines also say that women between the ages of 50 and 74 should receive mammograms every two years rather than annually. And the USPSTF says that there's not enough evidence to weigh the benefits and harms of mammograms in women 75 and older or to evaluate newer digital mammography or magnetic resonance imaging as screening techniques for breast cancer. Also, the task force recommends against instructing women how to do self-exams.
Everyone knows a woman whose breast cancer was caught early during her annual mammogram. What could possibly be troublesome about finding tumors before they've had a chance to leave the breast and invade elsewhere in the body?
The USPSTF, whose new screening advice was published in the Annals of Internal Medicine, agrees that mammography saves lives. Referring to a new review of the available evidence, it notes that the screening test cuts the death rate from breast cancer by about 15 percent for women in their 40s—similar to the effects for women in their 50s. (The benefit is significantly larger for women in their 60s.)
But the panel says that there are harms inherent in screening, including false-positive results that cause anxiety and lead to additional tests and invasive procedures such as biopsies. There's also the less-quantifiable risk of finding—and treating—very early invasive cancer or the "stage zero" cancer known as ductal carcinoma in situ (DCIS) that doesn't always progress to become life-threatening. "You can't just focus on the benefits," says Karla Kerlikowske, director of the women's clinic at the Veterans Affairs Medical Center in San Francisco, who wrote an editorial accompanying the USPSTF report. "You have to also think about all the healthy people who are undergoing these tests."
And cancer is more rare in younger women. The research cited by the USPSTF says that to avert one death from breast cancer, about 1,900 women in their 40s would need to be screened for a decade, compared to 1,300 women in their 50s and 400 in their 60s. After analyzing all this data, the USPSTF says that the net benefits after accounting for harms are small for women younger than 50. Women in their 40s, the task force says, should make personal decisions based on their feelings about the balance of benefits and harms. And women between 50 and 74, the task force says, should get mammograms only every other year, since models show that schedule should produce almost all the benefits with almost half the number of false-positive results.
Some take issue with the new guidelines. With these recommendations, the task force has made "a value judgment that's subject to discussion and interpretation," says Len Lichtenfeld, deputy chief medical officer for the American Cancer Society, which is sticking to its recommendation that women begin annual screening mammograms at age 40. Harms are tricky to measure. It's hard to quantify the psychological impact of additional tests and biopsies, for example. And estimates of overdiagnosis generally range only between 1 percent and 10 percent, according to the review consulted by the USPSTF. (Monetary costs weren't considered by the task force, says USPSTF Vice Chair Diana Petitti.) Lichtenfeld is also concerned about using computer models as the basis for the every-other-year recommendations, since so much is at stake.
Marisa Weiss, a Philadelphia oncologist and founder of Breastcancer.org, says the task force's conclusions were based on outdated assumptions about treatment and mammography. For example, studies show that digital mammography is more accurate among young women, but the USPSTF discussed only the standard film mammography. And it figured in certain harms that have been ameliorated over the years with procedures such as core biopsies rather than the more invasive open biopsies, as well as tests that can predict which women are likely to benefit from chemotherapy and which can skip it. She worries these recommendations will result in young women being entirely bypassed, so that women in their 50s will be diagnosed at later stages of cancer and will need more treatment.
All sides of the debate agree on several things: More research is necessary to more accurately capture an individual woman's risk of breast cancer and to ferret out the genetic or molecular characteristics of tumors that need more aggressive treatment and others that can be monitored for further changes. And most everyone acknowledges that mammography is imperfect and that women do not always have accurate information about what it can and cannot do. "We have oversimplified the message in a way that misrepresents the biology of the disease," says Barbara Brenner, executive director of Breast Cancer Action, a San Francisco-based advocacy group that has long questioned the emphasis on mammography. People with early breast cancer fall into three categories: a group of women with very aggressive disease that even routine mammography isn't likely to catch in time to prevent death, women with conditions like DCIS whose cancers may never become life-threatening, and a third group whose cancers are potentially dangerous and respond to current treatments, she says. The latter are the women helped by mammography, but it's not possible to know for sure who falls into that category.
The debate is over the women in whom to deploy an admittedly imperfect test until more is known about how to better predict who is most likely to reap its benefits, and over how that test should be used. Therese Bevers, medical director of the cancer prevention center and prevention outreach programs at M.D. Anderson Cancer Center in Houston, says that models might show that some low-risk populations more likely to develop less aggressive tumors could consider mammograms every two years. But a blanket recommendation to that effect is likely to miss aggressive tumors and pick up more of the slow-growing lesions, she says. Kerlikowske, however, says it makes sense to recommend against routine screening for women under 50, but that those with a close relative with breast cancer might instead start in their 40s with an every-other-year mammogram. Both acknowledge the test's flaws, but their starting points differ.
Lichtenfeld worries that the nuanced discussions about screening mammography may be lost in the shuffle. "The public needs to be informed and should be aware of the benefits and risks or harms of the test," he says. "The other side of the coin is that when the messages are confusing or conflicting or overly complex, the public will generally respond by saying, 'If they can't make up their minds, why should I do this test?' "
As for insurance reimbursement, since decisions are based on recommendations of many major groups (including the USPSTF and the ACS), this recommendation alone isn't likely to prevent women in their 40s from having mammograms covered by insurance. Petitti says the "C"-level recommendation given by the USPSTF is against routine mammography for women under 50, not against it in all cases.
Meantime, it's unclear whether women will follow the advice of the USPSTF or other bodies giving conflicting advice. "I think it points to a conversation with her doctor," Petitti says when asked about how women should take these recommendations. Weiss worries women are looking for a reason not to have an admittedly unpleasant test and that guidance such as this may give them the excuse to do so. The National Cancer Institute, for its part, says it will evaluate its own recommendations in light of today's report, including what women of above-average risk should do—a group the USPSTF did not address in detail. Stay tuned for more controversy.