New analyses support the recommendation that for a woman of average breast cancer risk, beginning screening for the cancer at age 50 and undergoing mammograms every other year through age 74 reasonably balances the potential benefits and harms associated with screening.
The U.S. Preventive Services Task Force based its current guidelines on 2009 findings, and the latest research — publishing in the Jan. 12 issue of Annals of Internal Medicine — was presented to the task force as it reviews more recent evidence on breast cancer screening.
The findings were determined by using six different independent simulation models to evaluate various screening strategies, including annual and biennial mammograms beginning at age 40, 45 and 50. The in-depth analyses were done by teams that are part of the Cancer Intervention and Surveillance Modeling Network, or CISNET, which is funded by the National Cancer Institute. Breast Cancer Surveillance Consortium researchers also contributed to the latest findings.
“CISNET’s charge is to create models that can test a large number of screening and treatment scenarios, and provide evidence that can be considered for public health recommendations for average risk women,” the paper’s lead author, Dr. Jeanne Mandelblatt of Georgetown Lombardi Comprehensive Cancer Center, and a principal investigator with CISNET, said in a statement. “But it’s important to remember that none of us is the ‘average’ woman.”
Among the findings: Screening every two years from ages 50 to 74 reduces the breast cancer rate by, on average, about 26 percent — averting seven breast cancer deaths per 1,000 women screened. Annual screening from age 40 to 74 averted three more deaths, but resulted in 1,988 more false-positives and seven more overdiagnoses of cancer. Improvements in technology, like digital mammography, seemed to enhance results somewhat, but not enough for researchers to back a general recommendation of screening earlier or more often than the USPSTF currently recommends for women of average breast cancer risk.
However, those with a higher risk for cancer — like a family history of the disease — tended to see greater benefit from earlier, more frequent screening, without the same uptick in potential harm from unnecessary treatment as those of average risk. Experts involved in the research and observers alike both say, as recommendations on when to beginning breast cancer screening and how often to get a mammogram differ, from 40s to 50, and annually or every other year, it remains for a woman to determine what’s best for her in conversation with her doctor. That means balancing potential benefits with concerns about possible harms, and also looking at individual risk factors.
“You don’t want to lose the big picture here,” says Dr. Harold Burstein, medical oncologist at Dana-Farber Cancer Institute, and an associate professor of medicine at Harvard Medical School in Boston. “The big picture is that mammograms are still a very important public health tool and reduce mortality from breast cancer. And, in general, women should be encouraged to get mammograms.”
He adds that millions of women who are advised to get mammograms still don’t do so or fail to do so as regularly as recommended by any major guidelines. “At best, about 30 percent of women aged 50 to 70 get screening at least once every two years. Rates are substantially lower in many socioeconomic and racially-defined subgroups,” he says.
On the flip side, many women begin undergoing mammograms earlier than any group recommends. Nearly a third of women report undergoing a mammogram before age 40, which is earlier than any medical organization recommends starting routine breast cancer screening, Robert Smith, vice president of cancer screening at the American Cancer Society, told U.S. News in November. Approximately 14.5 percent of women ages 35 to 39 say they received a mammogram in the past year, and 31.5 percent in that age group report having ever received a mammogram, according to a ACS analysis of data collected by the U.S. Census Bureau for the 2013 National Health Interview Survey, which captures information on a range of health topics.
The ACS revised its recommendations in October and now advises that women ages 40 to 44 have the choice to start breast cancer screening if they wish — suggesting they consider the risks as well as potential benefits — and that all women should begin annual mammograms by age 45, continuing through age 54, then switching to every other year starting at age 55.
By comparison, the American Congress of Obstetricians and Gynecologists currently recommends that women begin routine breast cancer screening at age 40 and then undergo a mammogram annually thereafter.
For women still trying to make heads or tails of all the back and forth on breast cancer screening, Burstein suggests it might be instructive to look outside the U.S. “It’s worth emphasizing that the revisions that have been proposed really bring the U.S. more into accord with what the rest of the world is doing. In Canada, the United Kingdom, Switzerland, Australia, Germany — most of the industrialized Western countries — they recommend mammograms beginning around age 50, every two years, for the most part,” he says.
Dr. Otis Brawley, the chief medical officer for the ACS, emphasized the overlap between the USPSTF recommendations and ACS breast cancer screening guidelines — rather than the differences. Both groups looked at the data, he says, and noted there’s some evidence that screening saves lives starting at age 40 and that there are harms associated with screening. “Twenty years ago we never talked harms, we only talked about benefits. Both groups said that women need to balance the risk and the benefit and make a decision,” he says. The ACS’s recently revised guidelines moved closer to the breast cancer screening recommendations from the USPSTF, but Brawley says the ACS has no plans to further tweak its guidelines.
ACOG also reasserted its guidelines on when women should get mammograms, while noting it’s seeking consensus going forward to bridge the confusion that currently exists over differing recommendations.
“ACOG continues to stand by our breast cancer screening recommendations, which provide for annual mammograms beginning at age 40. Evidence and experience have shown that early detection can lead to improved outcomes in women diagnosed with breast cancer,” Dr. Mark DeFrancesco, president of the American College of Obstetricians and Gynecologist, said in a statement.
But he added that, “In January, ACOG is convening a consensus conference with the intent to develop a consistent set of uniform guidelines for breast cancer screening that can be implemented nationwide. Major organizations and providers of women’s health care will gather to review and discuss the data in greater detail. We look forward to a positive outcome of this conference that helps to avoid the confusion that currently exists among the women we treat.”
Separately, Dr. Wanda Filer, president of the American Academy of Family Physicians, said in a statement provided to U.S. News that the organization agrees with USPSTF’s current recommendations: “Women attain the greatest benefit from a mammography starting at age 50. Women ages 40 to 49 attain less benefit with more risk, but should have the option of getting mammography after they discuss the risks and benefits with their personal physician.”
Wherever groups come down on current breast cancer screening guidelines, Burstein says women are perfectly capable of doing what they’ve done for years amid differing recommendations, and deciding for themselves, which guidelines best suit them — including taking into account over their own individual risk for breast cancer. “Trust yourself and trust the conversation you’re capable of having with your doctor to help you make the appropriate decision,” he says.
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New Analyses Support Biennial Mammograms Beginning at Age 50 originally appeared on usnews.com
