New Mammogram Guidelines: What Women Should Know

[Originally published: Sept. 22, 2023. Updated: April 30, 2024.]

Women who are at average risk for breast cancer should start mammogram screening at age 40 and get one every two years until age 74. That’s the latest recommendation from the U.S. Preventive Services Task Force (USPSTF), an independent, volunteer panel of national experts that makes recommendations focused on disease prevention.

Previously, the USPSTF said that women should start mammograms—X-ray examinations of the breast used to detect cancer and other breast diseases—at age 50. The new advice does not apply to women considered high risk, including those who have had breast cancer, carry genetic mutations that increase cancer risk, have had high-risk breast lesions on previous biopsies, or have experienced high-dose chest radiation before age 30. Women in this category should continue to follow their doctor’s advice on screening age and frequency.

The change is not based on new scientific data but a review of existing studies on breast cancer screening programs, cancer cases, and deaths in the United States. Breast cancer is the second most common cancer in women in the U.S., and the death rate is highest among Black women.

“For many years, there has been much debate about when women between ages 40 and 50 should start mammograms,” says Eric Winer, MD, director of Yale Cancer Center, as well as president and physician-in-chief of the Smilow Cancer Hospital Yale New Haven Health System.

For example, the American Cancer Society (ACS) recommends that women at average risk of breast cancer get a mammogram every year between ages 45 and 54. Women 55 and older can switch to a mammogram every other year or continue with yearly mammograms, the ACS says, with screening continuing at an annual or biennial (every other year) interval if they are in good health and expected to live 10 or more years.

Below, we talked more with Dr. Winer about the recommendations and what they mean for women.

The new guidelines are for “cisgender women and all other persons assigned female at birth” who are 40 years or older and are at average risk of breast cancer.

The guidelines also apply to women with dense breasts, which means there is more fibrous tissue in the breasts than fatty tissue, making it difficult to spot cancer on mammography.

However, for women with a first-degree relative (meaning a mother and/or sister) who has had cancer, “it is generally recommended to start screening 10 years younger than the first-degree relative was at the time of her diagnosis,” says Dr. Winer. “So, if your mom was 42 when she was diagnosed, you would start in your early 30s.”

The panel made its updated recommendations based on a systematic review comparing the effectiveness of mammography-based breast cancer screening strategies by age to start and stop screening, as well as screening intervals, use of supplemental imaging, breast cancer deaths, and other data.

There was no new clinical trial data, but the panel commissioned modeling studies to provide information about the benefits and harms of breast cancer screening strategies that vary by age of starting and by race.

The differing opinions about when a woman should start mammograms is largely because breast cancer is somewhat, though not dramatically, less common in women in their 40s compared to those who are older, Dr. Winer explains.

“Studies have not consistently shown a benefit in women between the ages of 40 and 50 receiving mammograms,” says Dr. Winer. “And there are false positives, which can lead to more invasive testing and over-treatment, particularly for early cancers that may never progress.”

But the USPSTF’s claim is that a new analysis of existing data suggests that perhaps there is more benefit, he adds.

“Plus, I think this may have been motivated by concerns about breast cancer in young Black women,” he says. “Even though, overall, Black women are less likely to get breast cancer than White women, young Black women are equally likely to get it and have a much higher chance of dying from it.”

Many women already start getting mammograms at age 40 since they are covered fully by insurance companies annually from 40 to 74. This means the new advice from the task force won’t change anything for them. But women who planned to start at 45 may now consider starting at 40.

“Choosing whether to start at 40 or 45 is the main decision point for most women of average risk,” Dr. Winer says. “If a woman is at a higher risk of getting breast cancer because of a family history or other personal factors, then it probably makes sense to start at 40.”

But people who are at low risk could still consider waiting until they're 45, he adds.

When the task force makes its recommendations, it does so with a balance between benefits (such as lives potentially saved by mammography) and possible harms (such as false-positive results that lead to more testing and invasive procedures, treating tumors that are slow-growing and would never be life-threatening, and radiation exposure).

The panel’s research said there was no benefit to annual mammograms compared to getting them every other year.

Still, many women will likely continue to get them every year while in their 40s, Dr. Winer says.

“For younger women starting mammograms, I would tend to err on the side of caution and do it yearly, but there are different opinions on this. Certainly, doing it every other year is better than nothing at all, and it might be just as good as doing it every year,” he says. “However, I think women with a higher risk should go every year until age 55, when I think switching to every other year would make a great deal of sense.”

There is stronger evidence in women over 55 that every other year screening is essentially equivalent to annual mammography, he adds.

While the seemingly constant—and sometimes conflicting—changes in screening recommendations for breast cancer can be confusing and frustrating for women, Dr. Winer points out that the differences in the recommendations are relatively subtle, and there are other steps a woman should take.

“Some studies have suggested that regular exercise may lower cancer risk, and certainly maintaining an optimal body weight after age 50 can help lower the risk. Women over 50 who are overweight or obese are at higher risk of developing breast cancer,” he says.

But just being a woman means there is some risk of breast cancer, and with that in mind, women need to be aware of their breasts so if there is something abnormal, they will immediately seek out the advice of their doctor, he adds.

“Women should also know that new and better treatments for breast cancer are constantly under development. Deaths from breast cancer continue to go down,” Dr. Winer says. “And by finding breast cancer early, some women will need that much less treatment, which usually means that the treatment is much easier to tolerate.”