Why are breast cancer screening guidelines so confusing? Here’s what you need to know.

The U.S. Preventive Services Task Force just released new draft guidelines on breast cancer prevention, and they're stirring up some questions. The panel of medical experts now recommends that women start having regular mammograms at age 40 — a huge departure from previous guidance, which said that women should start mammograms by age 50.

This is a draft recommendation — in other words, it's not final yet — but it's expected to become official in a few months.

According to the new draft guidelines, women should be screened for breast cancer every other year starting at age 40 to lower their risk of dying from the disease. "While the Task Force has consistently recognized the lifesaving value of mammography, we previously recommended that women in their 40s make an individual decision about when to start screening based on their health history and preferences," a statement from the Task Force says. "In this new recommendation, the Task Force now recommends that all women get screened starting at age 40. This change could result in 19% more lives being saved."

But the screening recommendations are different from those of other organizations, including the American College of Obstetricians and Gynecologists and the American Cancer Society — which are also different from each other. What's going on here, and why are breast cancer prevention guidelines so confusing? Doctors break it all down.

What led to the new mammography screening recommendations?

It's important to point out that the screening recommendations revert to what the Task Force used to recommend around mammograms. In 2009, the organization increased the recommended age for routine mammograms from 40 to 50. At the time, the panel expressed concerns that starting screening at age 40 could lead to unnecessary treatments, such as unneeded biopsies and other therapies over false positives for cancer.

But since then, breast cancer diagnoses have increased — especially in women under 50 and younger Black women, who are dying from breast cancer at nearly double the rate of white women of the same age.

“New and more inclusive science about breast cancer in people younger than 50 has enabled us to expand our prior recommendation and encourage all women to get screened in their 40s,” the Task Force wrote on its website. “We have long known that screening for breast cancer saves lives, and the science now supports all women getting screened, every other year, starting at age 40.”

Dr. Christine Edmonds, an assistant professor of radiology at the Hospitals of the University of Pennsylvania, tells Yahoo Life: "There is overwhelming evidence that, for women at average lifetime risk of breast cancer, beginning screening at age 40 saves the most lives, as compared to beginning at age 45 or 50. In addition, the most life-years are lost to breast cancer among women diagnosed in their 40s as compared to women diagnosed in any other decade of life."

Edmonds says that when you factor that in with knowing there is "minimal risk" to screening women in their 40s, "it is with a resounding 'yes' that we recommend women begin screening no later than age 40."

Dr. Melissa D. Fana, director of women’s health for Suffolk County at NYU Langone's Perlmutter Cancer Center, tells Yahoo Life that the new recommendations are a "very important step in protecting women," adding, "We know mammography saves lives."

But many doctors say they've been recommending that women get screened for breast cancer starting at age 40, regardless of what the Task Force said in the past. "That has been our practice despite the earlier guidelines," Dr. Parvin Peddi, a medical oncologist and director of breast medical oncology for the Margie Petersen Breast Center at Providence Saint John’s Health Center, tells Yahoo Life. "There are still many patients diagnosed prior to 50."

Edmonds and Dr. Therese Bevers, medical director of the Cancer Prevention Center at MD Anderson Cancer Center, also tell Yahoo Life that their medical centers recommend annual screenings for average-risk women.

How often should people be screened who are average risk vs. higher risk?

The Task Force guidelines say that all women should start regular mammograms at age 40, but women who are considered high risk may need to start screening even earlier.

"Women at higher risk of breast cancer should also be screened annually," Edmonds says. "The age of screening onset depends on their specific risk factors and level of risk and should be determined by a breast cancer specialist. Those who are at greater than or equal to 20% lifetime risk of breast cancer should be screened with annual breast MRI." (Factors such as your family and personal history can weigh into your risk for breast cancer.)

"There are some very good risk analyses you can do online to figure out your risk," Dr. Michele Blackwood, chief in the section of breast surgery at the Rutgers Cancer Institute of New Jersey, tells Yahoo Life. "If your lifetime risk is 20% or higher, you definitely are high risk."

Why do some organizations have different guidelines than the new U.S. Preventive Services Task Force's recommendations?

The American College of Obstetricians and Gynecologists recommends that women have mammograms every one to two years, starting at age 40 — and the organization has held that recommendation for years. The American Society of Breast Surgeons also recommends annual screenings at 40, and the American Cancer Society suggests getting mammograms starting at age 45. Why is there a difference?

"We don't know what makes them do what they do," Blackwood says. "The [Task Force] recommendation to wait until 50 was confusing." Blackwood is in favor of annual screenings, rather than the Task Force's latest recommendation of every other year. "If you do them annually, you'll pick up cancers at earlier stages," she says.

A lot of why organizations recommend annual vs. biannual (every other year) screenings comes down to risk assessment, Bevers says. "The organizations that say to have mammograms annually are saying, We know that fewer women will die from breast cancer this way," she says. "The organizations who say to get screened biannually want to minimize possible harm of false positives."

The Task Force noted online that the organization analyzed modeling on the risks and benefits of screening every year or every other year and found that "when you balance lives saved against harms like unnecessary follow-up and treatment, women benefit more when screening is done every other year."

But experts say it's really best to get an annual mammogram. "The reasons provided by the [Task Force] for biennial as opposed to annual screening — potential for callbacks, for example — are nebulous, at best," Edmonds says.

Why isn't dense-breast guidance included and why is that important?

Women with dense breasts have an increased risk of developing breast cancer — something the Task Force acknowledges. However, the organization also says that it doesn't have specific recommendations for women with dense breasts just yet.

"We still don't have sufficient data to make clear screening recommendations in terms of who needs supplemental screening and how to provide this supplemental screening among women with dense breasts," Edmonds says. "Much more research is needed to better understand who may need supplemental screening, when in their lives they warrant supplemental screening and how to screen them."

What does this all mean for insurance?

The Task Force recommendations usually guide insurance coverage of screening tests, Bevers says. "Thus, a recommendation to begin screening mammography at age 40 protects insurance coverage for women age 40 and above," Edmonds says.

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