New guidance from the U.S. Preventive Services Task Force says women at average risk of breast cancer should start having mammograms, every other year, when they turn 40. For years, the recommendation had been to start at age 50. Photo by Rhoda Baer/Wikimedia Commons
In a major change from its longstanding advice, an influential medical panel now recommends that women start mammography screening for breast cancer at age 40.
The new guidance, from the U.S. Preventive Services Task Force, says women at average risk of breast cancer should start having mammograms, every other year, when they turn 40. For years, the recommendation had been to start at age 50 -- though women in their 40s were advised to talk with their doctor and choose what was best for them.
The change, published as a draft recommendation on Tuesday, brings the task force guidance more in line with what other medical groups advise.
Those groups -- including the American Cancer Society and the American College of Obstetricians and Gynecologists -- have long recommended that all average-risk women start mammography screening in their 40s.
Given that, many U.S. women are already getting screened, or at least thinking about it, once they turn 40, said Dr. William Dahut, chief scientific officer at the cancer society.
But he also saw the new recommendation as good news.
"I hope this eliminates any confusion among the primary care doctors who advise women on screening," Dahut said.
The USPSTF is an independent panel of medical experts, funded by the government, that analyzes the research evidence on various preventive medical services -- like cancer screenings -- and makes recommendations on who should have them, and how often.
It also periodically updates those recommendations to consider the latest research. The panel last updated its breast cancer screening recommendations in 2016.
Dr. John Wong, a task force member, explained what drove the change in starting age. For one, he said, breast cancer rates are rising among U.S. women in their 40s -- by 2% a year, on average, since 2015.
"And we now have new and more inclusive science on women younger than 50," said Wong, a professor of medicine at Tufts University School of Medicine in Boston.
That, he added, includes more data on women of color.
In the United States, Black women have a 40% higher death rate from breast cancer than white women, even though they are not more likely to develop the disease. And that disparity is concentrated among relatively younger women.
Based on the latest data, the task force estimates that starting mammography screening at age 40 could save just over one additional life per 1,000 women over a lifetime of screening.
"And we think that Black women could get even more benefit," Wong said.
He stressed that the recommendation applies only to average-risk women. Women at high risk of breast cancer -- due to genetic mutations, for instance -- should talk to their doctor about the best screening plan.
The task force still differs from other groups in its advice on mammogram frequency: every other year, instead of annually.
Two of those groups issued a statement in response to the draft recommendation, urging it to go further and support annual exams.
"Medical experts should clear the confusion caused by differing recommendations and agree to recommend yearly mammography for average-risk women starting at age 40," according to the statement from the American College of Radiology and the Society of Breast Imaging.
The groups worry about the cancers that could be missed with biennial screening, and that minority women would be disproportionately affected.
The American Cancer Society also recommends yearly screening, but is more flexible on age -- advising women to start by age 45 and at least consider it in their early 40s. (Dahut said the ACS is in the process of updating its advice, however.)
Wong said the task force recommendation is based on a weighing of the benefits versus risks of screening. Cancer screening, by definition, is done when people are ostensibly healthy, and the main "harm" is that it can generate false-positive results. That leads to needless follow-up testing, sometimes with an invasive biopsy -- not to mention anxiety, Wong noted.
According to the panel's calculations, annual mammography leads to 50% more false positives over a lifetime of screening, compared with screening every other year.
As for when to stop screening, Wong said there was not enough evidence to recommend for or against screening after age 74.
A central issue is that cancer screening needs to not only detect more early-stage tumors -- but also make people's lives "healthier and longer," Wong said.
Back in 2016, there had not been enough evidence that screening women in their 40s achieved that, according to the task force. That kind of evidence is still lacking for women age 75 and up.
So those women should speak to their doctors about whether they want to continue screening, Wong said.
The task force also took on the question of whether women with dense breasts should have supplemental screening -- with ultrasound or MRI -- in addition to regular mammograms. Again, it said, there is not enough evidence to make a call.
Nearly half of women over 40 have dense breasts, which means they have more fibrous or glandular tissue than fat.
Those women have a relatively greater risk of developing breast cancer, Dahut said, and the dense tissue makes it harder to detect tiny tumors on a mammogram. So following up with an ultrasound or MRI scan may spot abnormalities that were initially missed.
Like the task force, the cancer society has no specific screening recommendation for women with dense breasts. But, Dahut noted, many U.S. women with dense breasts, after talking to their doctors, are already getting supplemental screening.
"And it's certainly reasonable for them to do so," he said.
Where everyone agrees, Wong and Dahut said, is that women in their 40s should start screening, and then continue at regular intervals.
In the United States, breast cancer is the second most common cancer and the second leading cause of cancer death. Last year, an estimated 43,250 women died of breast cancer.
The U.S. National Cancer Institute has more on breast cancer screening.
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