ost women should wait until age 45 to start getting annual mammograms and should cut back to every-other-year testing at 55, the American Cancer Society advised Tuesday in a major shift in its guidelines for breast cancer screening.
Until now, the group — one of the most respected voices on cancer — urged women to get yearly mammograms from 40 onward. But studies have shown that mammograms, even when they detect tumors, have little effect on whether a young woman will die of breast cancer.
About “85 percent of women in their 40s and 50s who die of breast cancer would have died regardless of mammography,” Drs. Nancy Keating and Lydia Pace of Brigham and Women’s Hospital wrote in an editorial accompanying the new guidelines published in the Journal of the American Medical Association.
The cancer society also recommended for the first time that women forgo breast exams performed by their doctor because they are not as effective as mammograms at finding tumors.
READ MORE: Experts debate: When should women start getting mammograms?
The changes move the cancer society guidelines closer to those issued in 2009 by a government-sponsored panel, the US Preventive Services Task Force. Like those earlier guidelines, the cancer society’s new position was sharply criticized by some physician groups.
In the United States, an estimated 232,000 women will be diagnosed with breast cancer this year; 40,000 will die of it.
The new mammogram recommendations are “important because of the stature of ACS,” said Dr. Russell Harris of the University of North Carolina, an expert on preventive medicine. While other medical groups have also cautioned that mammograms are not as effective as once thought and should be done less frequently, he said, the cancer society is better known and widely trusted.
The group raises millions of dollars for research and education, and its local volunteers drive patients to appointments and offer one-on-one support.
The cancer society acknowledged, however, that many women might still decide to get annual mammograms starting at 40. Women whose priority is having an incipient tumor detected — no matter the harm that could result from needless follow-up procedures — may choose that route, said Dr. Richard Wender, who led the society’s guidelines group.
Insurers in Massachusetts indicated that they would not change their coverage policies based on the cancer society’s new guidelines. “Our approach is going to be, leave it to the doctor and patient,” said Dr. Michael Sherman, chief medical officer of Harvard Pilgrim Health Care.
Blue Cross Blue Shield of Massachusetts, the state’s largest carrier, said in a statement that it covers mammograms as recommended by the US Preventive Services Task Force: every two years for women 50-74 who are not high risk.
The debate over screening mammograms, in which asymptomatic women undergo X-rays to detect possible malignancies, has raged since the 1990s. Although mammograms were once considered an effective way to find breast cancers at an early, more treatable stage and thus save lives, more than 25 years of research has dimmed that hope.
It turns out that some cancers detected by mammograms would never have posed a threat to a woman’s health or life. Others are so slow-growing that even if they’re not detected until they cause symptoms, they’re treatable. Still others are so aggressive that even catching them early is too late.
The cancer society’s new recommendations apply to the roughly 90 percent of women with an average risk of breast cancer. Guidelines for those with mutations associated with the disease, a personal history of invasive breast cancer, or a family history that gives them a 20 percent or greater risk are due next year.
When the group last addressed breast cancer screening, in 2003, it recommended that women begin annual mammograms at 40. Now it says women 40 to 44 should “have the opportunity” to get screened, in consultation with their doctor.
The recommendation for 40- to 44-year-olds reflects, in part, their low risk of breast cancer: 6 of every 1,000 women get breast cancer during those five years. When risk is so low, any benefit from mammograms is outweighed by harms from screening, Wender said. Those include false positives, in which a mammogram detects something suspicious and a woman is called back for additional X-rays that reveal no disease, and overdiagnosis, in which a suspicious spot harbors malignant cells that would never have threatened the woman’s health. Because mammograms don’t show which tumors are dangerous, some of these women may undergo unnecessary surgery and treatment.
Women 45 to 54 should have annual mammograms, the group says, reiterating its 2003 recommendation, though it acknowledges that evidence of net benefits from annual screening is weaker than the evidence for some screening, regardless of the frequency.
The 2003 recommendations urged annual screenings until women were in poor health and near the end of their lives. Now the group recommends that women 55 and over transition to biannual mammograms and stop when their life expectancy is less than 10 years.
Age 55 is a proxy for menopause. The advice to reduce mammogram frequency reflects results of a study in JAMA Oncology also published on Tuesday. It found that in postmenopausal women, mammogram intervals (every year or every two years) had no effect on the size or stage of a breast cancer, justifying two-year screening.
But in premenopausal women, those diagnosed with breast cancer after biannual mammograms are slightly more likely to have larger, more advanced tumors (26 percent) than those who received annual mammograms (20 percent).
That suggests annual screenings are beneficial for detecting more aggressive cancers, although that may not reduce mortality.
Although mammograms incite the most passion, the cancer society’s recommendation to stop clinical breast exams is likely to especially startle women.
Randomized trials have found that, for 40- and 50-something women, mammograms decrease deaths from breast cancer about 15 percent. Observational studies, while less definitive, find a somewhat larger benefit; the cancer society analysis settled on about 20 percent.
In absolute terms, said the Brigham’s Keating, mammograms likely avert about five deaths from breast cancer among 10,000 women in their 40s, and 10 deaths among 10,000 women in their 50s.
When she talks to patients, Keating said, “I ask them, how do you feel about being one of the few women to have your life saved by mammography versus the possibility of unnecessary tests and treatments?”
Radiologists, who administer mammograms, blasted the new guidelines. “If a woman wants to reduce, as much as possible, her risk of dying of breast cancer, she will choose yearly mammography starting at age 40,” Dr. Debra Monticciolo of the American College of Radiology said in a statement.
The American College of Obstetricians and Gynecologists said it is maintaining its longtime advice to start mammograms at age 40, continue them annually or biannually, and undergo clinical breast exams. The group explained that it places a different weight than the cancer society on the harms versus the benefits of mammograms.