To counteract growing rates of breast cancer in younger women and to reduce racial disparities in deaths, an influential panel has changed its advice and is urging most women to begin getting regular mammograms at age 40.

The new recommendations from the U.S. Preventive Services Task Force say women without genetic mutations that make it extremely likely they will develop breast cancer should get their first mammogram to screen for the disease at age 40 and should continue with the exams every other year until they turn 74. The guidelines were published Tuesday in the Journal of the American Medical Assn.

Breast cancer is one of the most common cancers among women in the U.S., as well as one of the deadliest. An estimated 297,790 U.S. women were diagnosed with the disease last year, and 43,170 died of it, according to the American Cancer Society.

The task force, a group of 16 experts convened by the federal government, sparked an uproar 15 years ago when it said women could wait until 50 to begin regular, biennial breast cancer screening — much later and less frequent than what other medical groups were recommending at the time. The group’s rationale was that women in their 40s faced a low risk of breast cancer and that frequent testing of asymptomatic women in this age group caused too many to endure biopsies and other invasive procedures that were unnecessary and potentially dangerous.

The task force reaffirmed its controversial position in 2016. But when the time came to update its guidelines again, two facts stood out.

First, the incidence of invasive breast cancer in younger women, which had been slowly climbing since at least 2000, began to accelerate around 2015, rising by an average of 2% per year over the following four years.

Second, the task force recognized that among all racial and ethnic groups, Black women are most likely to be diagnosed with breast cancers that have progressed beyond stage 1, including the aggressive “triple negative” tumors that are particularly difficult to treat. Black women also have the highest mortality rate from breast cancer — about 40% higher than that of white women — “even when accounting for differences in age and stage at diagnosis,” the task force wrote in JAMA.

After analyzing data from randomized clinical trials and models based on real-world data, the panel determined that starting biennial mammograms at 40 instead of 50 would prevent an additional 1.3 breast cancer deaths per 1,000 women over the course of their screening lifetimes. For Black women, starting a decade earlier would avert an additional 1.8 deaths per 1,000 women.

“This is a big change, absolutely,” said Dr. Stamatia Destounis, chair of the American College of Radiology Commission on Breast Imaging. “We all realize that if you start to screen a woman at 40, you’re going to find the most cancers.”

Robert Smith, the American Cancer Society’s senior vice president for early cancer detection science, said the task force’s new guidance is more in line with advice from other medical organizations, including his own.

“We don’t want any woman to have a breast cancer diagnosed late if it can be avoided,” Smith said. “There’s no substitute for finding a breast cancer sooner in its natural history.”

But Ricki Fairley, founder and chief executive of Touch, the Black Breast Cancer Alliance in Annapolis, Md., said that if the goal is to reduce racial disparities, screening starting at age 40 isn’t nearly enough.

“I’m dealing with patients right now that are 24, 23, and are having breast cancer and dying,” said Fairley, a breast cancer survivor who was diagnosed at age 55. “Getting a first mammogram at age 40 is way too late for Black women.”

Reonna Berry, president and co-founder of the African American Breast Cancer Alliance in Minneapolis, criticized the task force for sticking with its advice to screen every other year.

“If we waited every two years to get a mammogram, a lot of Black women would be dead,” said Berry, who was diagnosed with breast cancer at 38 and again a few years ago, in her late 60s.

A radiologist reviews a mammogram at UCLA.

(Jay L. Clendenin / Los Angeles Times)

The American College of Radiology and the Society of Breast Imaging recommend annual screening starting at 40. The American Cancer Society recommends annual screenings for 45- to 54-year-olds, then screening every year or two after that. In addition, the ACR advises Black women to conduct a risk assessment and devise a screening strategy with a doctor when they are 25, Destounis said.

Smith said that although Black women under 40 are more likely than their white counterparts to be diagnosed with breast cancer, the difference isn’t large enough to warrant widespread screening.

According to data gathered by the National Cancer Institute, there are 38 breast cancer cases per 100,000 Black women between the ages of 30 and 34, compared with 32.3 cases per 100,000 white women in the same age group. For women ages 35 to 39, the respective figures are 74.8 and 69.2. In both age groups, that amounts to fewer than 6 additional breast cancers per 100,000 women.

Smith and others criticized the task force for failing to endorse screening mammograms for women over 74. As in years past, the panel determined there wasn’t enough evidence to make a recommendation one way or another.

“At the age of 75, the risk of breast cancer is very high,” Smith said.

There are 473.2 cases per 100,000 women of all racial and ethnic backgrounds between the ages of 75 and 79, and 425.8 cases for ages 80 to 84, the National Cancer Institute reports.

“There’s no reason, at least in our judgment, that women should stop screening as long as they’re in good health and expect to live another 10 years,” Smith said.

Dr. John B. Wong, a vice chair of the task force, said the lack of evidence regarding mammograms for older women is “totally frustrating.”

There are no randomized clinical trials with women in this age group, but the panel did consider a cohort study of more than 1 million Medicare patients that found no benefit to screening women ages 75 to 84, Wong said.

The situation was similar regarding the use of ultrasound or MRI as supplemental screening tools for women with dense breasts, he said.

“We know that they’re at increased risk, and we know mammography doesn’t work as well for them,” Wong said. “We would love to have some evidence to help us decide what to recommend about what they should do.”

On the question of screening frequency, the task force had enough data to act. With biennial screening between the ages of 40 and 74, there will be about 1,376 false-positive results per 1,000 women over their lifetimes, along with 14 instances of doctors finding and treating early-stage tumors that might never have become dangerous if left alone. Both would increase by about 50% if women were screened annually, Wong said.

The panel concluded that screening every other year prevents more deaths and results in more years of life gained per mammogram, producing a better balance of benefits and harms.

Dr. Julie Gralow, chief medical officer for the American Society of Clinical Oncology, said she would weigh those trade-offs differently.

“As a breast cancer doctor, I’m on the receiving end of everybody who’s diagnosed, and I think they way overplayed the harms versus the benefits,” she said, particularly the anxiety that would stem from being asked to come in for follow-up imaging. “I know for some women that’s very scary and all, but it’s almost a paternalistic kind of view.”

That notion was echoed by Karen Eubanks Jackson, founder and CEO of Sisters Network, a national breast cancer organization for Black women.

“We understand that having too many mammograms can sometimes not be in your favor,” said Jackson, a breast cancer survivor. “But as a Black woman having had it four times, I’d rather be false positive than be positive and not know it. Give me my choice.”

Gralow emphasized that the task force recommendations do not apply to women with any kind of breast abnormality.

“If you have any symptom, then you should go straight to diagnostics, and that should be done at any age,” she said.

In Smith’s ideal world, precision medicine would allow doctors to replace broad guidelines with individualized screening recommendations based on the information in each woman’s health records.

“They might say, ‘Start screening at an earlier age’ or ‘Screen every year’ or ‘You can go every other year, and that’s just as safe,’ ” Smith said. “The sooner we move in that direction, the better.”