A U.S. government group recommends that women delay getting regular mammograms until age 50, instead of 40, the age at which the American Cancer Society (ACS) has long advised women to begin screening for breast cancer. The government group issued its new guidelines Monday, citing evidence that the benefits of regular screening do not justify the potential harms in younger women.
The U.S. Preventive Services Task force (USPSTF), funded by the Agency for Healthcare Research and Quality, published its recommendations in Annals of Internal Medicine; its decision was based on an analysis of existing trials that looked at the impact of mammography on breast-cancer deaths. The task force further recommended that women between ages 50 and 74 get screened every two years instead of annually, and that doctors no longer urge women to conduct monthly breast self-exams, since the practice does not appear to significantly reduce the risk of death from breast cancer.
Although the relative benefits of routine breast-cancer screening have been increasingly questioned by many within the cancer community, not everyone agrees that reducing mammography is the answer. "I am appalled and horrified," says Dr. David Dershaw, director of breast imaging at Memorial Sloan-Kettering Cancer Center in New York City in response to the new guidelines. "There is no doubt that mammography screening in women in their 40s saves lives. To recommend that women abandon that is absolutely horrifying to me."
For its part, the American Cancer Society holds firm to its position recommending yearly mammograms for women beginning at age 40 adamantly stating that it will not modify its guidelines. "We are not changing current recommendations at this time based on our initial review of the information provided by the task force," says Dr. Len Lichtenfeld, deputy chief medical officer for the ACS.
So where does this division leave American women, who have been instructed for nearly two decades to get yearly mammograms starting at age 40? That depends on whether patients and their doctors prefer their screening guidelines to be conservative or not. Experts say that compared with other cancer groups, the USPSTF has traditionally had the most conservative recommendations on mammography screening. In 2002, relying on much of the same data on which it based its new guidelines, the panel called for breast-cancer screening in women ages 40 to 49 every one or two years, even while other groups, including the ACS and the National Comprehensive Cancer Network (a coalition of National Cancer Institutedesignated hospitals), advocated yearly screening.
It should be noted that the new guidelines apply to women who are at average risk of breast cancer, not to women who are considered high risk, such as those with a genetic or familial history of the disease.
Cancer doctors are also worried that insurance companies will use the panel's new recommendations as an excuse to stop paying for mammography in younger women. Since 2002, when most professional organizations urged annual mammograms for women between 40 and 49 years old, the breast-cancer mortality rate in that group has steadily dropped, by about 3% a year, owing in large part to enhanced screening; doctors were able to pick up and treat cases of disease earlier.
Congress mandates that Medicare cover annual mammograms for its beneficiaries, but if private insurers adopt the task force's policies, then many women may soon find themselves at odds with their doctors, who may continue to advise annual screenings even if patients have to pay for them out of pocket. "That would be a step backward, taking away an option from women and denying them the choice," says Dr. Mary Daly, chairperson of the department of clinical genetics at Fox Chase Cancer Center in Philadelphia.
The new recommendations are based on analyses of two sets of data. In the first analysis the task force examined the results of existing trials on mammography, much of which had not changed since the panel last considered the issue in 2002; this time, however, the data was re-evaluated taking into account the current, and better, understanding of the potential harms associated with mammography information that shifts the balance of risks versus benefits of screening.
The task force's second data set comes from computer-modeled predictions of breast-cancer incidence and death rates based on various screening scenarios. The models were run by researchers at the National Cancer Institute (NCI), who compiled data from six cancer centers around the country, and plugged it into 20 separate age- and time-based screening protocols from screening women ages 49 to 69 every year and every two years, for example, to screening only women ages 60 to 69 every year and every two years as well. By switching from annual to biennial exams, these women would maintain 85% of the screenings' benefit in reducing breast-cancer death, while cutting risks from the test 50%.
Overall, the analysis suggests that mammography reduces the risk of dying from breast cancer 15% among women 39 to 49 years old. But the task force determined that while mammograms certainly reduced risk of death, that reduction was small in this age group in light of the risks associated with the screening. In order to save one life among 40- to 49-year-olds, doctors would have to perform yearly mammograms in 1,904 women over 10 years. Among older women, between ages 50 and 74, one death could be prevented for every 1,339 women screened for 10 years. Risks of screens include anxiety over inconclusive images that require additional testing, as well as the psychological and physical costs of further testing based on false-positive results of the screen. "They're saying that we should take away mammography for women in their 40s because we judged that these factors the risk of false positives, and anxiety and the discomfort of compression during the test outweighs the value of lives saved," says Dershaw.
It's not clear yet how the task force's recommendations will impact the decisions that women and their physicians will make about mammography in coming years, but already doctors are fearing the worst. "We could erode the progress we made in reducing breast-cancer mortality over the past decade or so because now the breast cancers are going to be larger when we find them, and more likely to be at a more advanced stage," says Dr. Therese Bevers, professor of clinical cancer prevention at M.D. Anderson Cancer Center in Houston. She adds, "Even including the risk or harms of screening, we still believe strongly that the benefits outweigh the risks when it comes to mammography."
But every time recommendations are changed, or when respected medical organizations endorse conflicting guidelines on issues like screening, say experts, many patients opt out of the controversy altogether, preferring to forgo testing than wade through the confusing information and options presented to them. So, says Dr. George Sledge, president-elect of the American Society of Clinical Oncology and a professor of medicine at Indiana University's Simon Cancer Center, it's worth remembering that "the core issue is that screening mammography reduces breast-cancer mortality. And that is unchanged by this report."