Breast cancer is the most common cancer in women, and the current recommendation is for all women of average risk to have a mammogram every year, starting at 40. But what if there were an alternative to the one-size-fits-most approach — one that matched the frequency of screening to the woman’s individual risk for developing cancer?
A large national trial of about 46,000 women, 40 to 74 years old, found that the stratified approach to screening worked as well in detecting tumors as universal yearly screening, and in fact lowered the chance that cancers would not be found until they were at a more advanced stage, although the difference was not statistically significant.
The study randomly assigned 14,212 women to be screened based on their individual risk, while 14,160 women continued with routine annual mammograms. Other participants recruited for the study who did not want to be randomly assigned to one group or another were allowed to choose their screening approach; 89 percent chose risk-based screening.
Each woman in the risk-based screening group underwent a comprehensive evaluation that considered the results of genetic testing, age, personal health history, lifestyle, breast density and factors such as the number of children they had and age at which they first menstruated.
The women were divided into four groups: Those deemed at lowest risk for breast cancer were told to wait until they were 50 to start mammography, while those at highest risk were screened twice a year, regardless of age, once with a mammogram and once with more expensive magnetic resonance imaging.
The results of the study, which was called WISDOM, were published online in The Journal of the American Medical Association and presented on Friday at the San Antonio Breast Cancer Symposium.
“This is the first randomized trial of risk-based screening, and the results are great, actually,” said Dr. Laura J. Esserman, the study’s lead author and the director of the breast care center at the University of California, San Francisco. “We don’t treat breast cancer as if it’s one disease anymore, so it really doesn’t make sense for us to screen as if everyone has the same risk for the same disease.”
After the results were unveiled on Friday, Dr. Eric Winer, the director of the Yale Cancer Center, who was in the audience but had not been involved in the research, stood up and said the work was “probably the most important study that’s been presented at this meeting.”
“It is practice-changing,” Dr. Winer said in an interview later. “For years, we have been doing mammography for everyone based on age and not paying attention to risk, and in order to achieve a small improvement in mortality, we do hundreds of thousands of mammograms every year.”
He added, “The researchers wanted to make sure that by backing off on screening in lower-risk patients, they wouldn’t be increasing diagnoses of somewhat more advanced cancers, and they showed you could do just that.”
“I think it has huge public health implications,” he said.
Another oncologist, Dr. Larry Norton of Memorial Sloan Kettering Cancer Center, who was not involved in the research, said the study represented “the start of a new process of risk stratification of screening tools for all cancers.”
“There’s more work to be done before we can recommend this, but it’s a step in the right direction,” Dr. Norton said.
The risk-based approach did not lower the number of biopsies that were done in the risk-based screening group, however, despite the fact that fewer mammograms were done, Dr. Norton said, adding that this was disappointing.
Each woman had an extensive individual risk assessment, including testing for genetic mutations like BRCA1 and BRCA2 but also for smaller changes in DNA that help predict breast cancer risk.
The study is one of the first to offer genetic testing to all women regardless of family history, and it found that 30 percent of women who tested positive for a genetic variant that raised their breast cancer risk did not report having any breast cancer in their family. Normally, these women would not be offered genetic testing, meaning their higher risk might not be known and taken into account.
“That tells us family history is not the way to determine who should get extra screening,” Dr. Esserman said.
About one-quarter of the women were determined to be in the lowest risk category and were told to hold off on screening until age 50, or until an algorithm predicted that their risk was equivalent to that of a 50-year-old.
Sixty-two percent of the women were deemed at average risk and were told to undergo screening every two years.
Women at elevated risk, who made up 8 percent of the cohort, were advised to be screened every year, while those deemed to be at the highest risk — about 2 percent of the women — were screened every six months, regardless of age, alternating between mammograms and magnetic resonance imaging.
Those women who were at elevated or highest risk for cancer also were given personalized recommendations on how they could reduce their risk, make decisions about breast health, diet and exercise, and consider risk-reducing medications. Screening is not enough, Dr. Esserman said, adding, “We should be looking at people’s risk and trying to reduce it.”
The United States spends about $12 billion on breast cancer screening every year, but the process needs improvement, she said.
“We’re still screening the way we did in 1980s,” Dr. Esserman said. “Every time a celebrity has breast cancer, we hear the message that ‘screening every year starting at 40 is what’s going to save you.’ But it doesn’t necessarily find those who are at highest risk.”
Roni Caryn Rabin is a Times health reporter focused on maternal and child health, racial and economic disparities in health care, and the influence of money on medicine.
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