What to Know About Mammogram Screening Guidelines and When to Start Mammograms

Here’s what the current mammogram guidelines say about when to start mammograms, how often you should get a mammogram, and more

Getting regular mammograms has a very clear benefit: helping to find breast cancer at an early stage—possibly even years before physical symptoms appear—when treatment is most likely to be successful.

What’s murkier, however, are mammogram screening guidelines, since recommendations vary depending on the medical professional organizations that issue them. While these groups are getting closer to a consensus on specific recommendations, such as when to start mammograms, some differences remain.

Read on to learn about the current guidelines and what you should know about them.

At what age should I start getting mammograms?

The right age to begin screening varies depending on your personal risk factors for breast cancer. If you’re at average risk, the recently updated United States Preventive Services Task Force (USPSTF) guidelines recommend starting mammogram screening at age 40 and getting one every two years until age 74. For women 40 to 49, this is a shift from the task force’s previous mammogram guidelines (published in 2016), which advised women at average risk of breast cancer in this age group to work with their doctors to make an individualized decision about when to start mammograms.

Why the change? Even though the disease is uncommon in women in their 40s, rates of breast cancer in younger women have been gradually rising since 2000, and they increased significantly from 2015 to 2019, with a 2 percent rise each year. By starting regular mammograms at age 40, the USPSTF estimates that nearly 20 percent more lives can be saved. Black women in particular stand to benefit from starting regular screening at age 40 since they develop and die of breast cancer earlier than non-Hispanic white women.

This update puts USPFTF in line with many other medical professional organizations’ guidelines that recommend starting mammograms at age 40, including the American College of Radiology (ACR), American Society of Breast Surgeons (ASBS), and the American College of Obstetrics and Gynecology (ACOG). One notable exception is the American Cancer Society (ACS), which advises starting at age 45, with screening being optional between ages 40 and 44.

How often should you get a mammogram?

These organizations remain split on how frequently women with an average risk of breast cancer should be screened. Some, such as ACBS and ACR, recommend getting annual rather than biennial (every two years) mammograms, while ACOG advises women to get screened every 1 to 2 years based on shared decision-making with their doctor. ACR’s mammogram screening guidelines recommend annual screening until age 54, stating that women can consider switching to biennial mammograms when they turn 55.

Why is there so much conflicting advice on how often you should get a mammogram? Even though these organizations look at the same data on the risks and benefits of mammograms to make their decisions, they don’t always interpret it the same way.

“Guidelines are just that: guidelines. They’re extremely useful in the aggregate and help doctors in the clinic,” BCRF’s Chief Scientific Officer Dr. Dorraya El-Ashry said. “But an individual woman’s screening decisions should always be made in conversation with her doctor and considering all of her potential risk factors.”

What are the mammogram guidelines for women at high risk of breast cancer?

High-risk women should start getting yearly high-risk breast cancer screening and mammograms earlier than women at average risk of breast cancer, typically around age 30 or even earlier. Women at high risk include those who:

• Have a known BRCA1 or BRCA2 mutation. While anyone can have these mutations, they’re more common in Ashkenazi Jewish women.
• Have a first-degree relative (parent, sibling, or child) with a BRCA1 orBRCA2 gene mutation.
• Have a lifetime risk of breast cancer of about 20 to 25 percent or greater, according to risk assessment tools conducted by a doctor.
• Have Li-Fraumeni syndrome, Cowden syndrome, or Bannayan-Riley-Ruvalcaba syndrome, or have first-degree relatives with one of these conditions.
• Had radiation therapy to the chest before they were 30 years old.

To ensure that women who need earlier high-risk breast cancer screening receive it, ACR released updated guidelines in 2023 that call for all women—and particularly Black and Ashkenazi Jewish women—to undergo a breast cancer risk assessment with their physician by age 25.

If you’re identified as a high-risk patient, you may need to get mammograms and breast MRIs regularly. While mammograms are highly accurate, they aren’t perfect and do miss some cancers—particularly in women with dense breasts. Half of women over the age of 40 have dense breasts and that number is even higher for women under 40. Breast MRI provides more detailed images and helps identify breast cancers earlier. Your doctor may recommend timing your mammogram and MRI together or alternating the two every 6 months.

Are there specific mammogram screening recommendations for women with dense breasts?

Women with dense breasts—breasts with relatively high amounts of glandular tissue and fibrous connective tissue and relatively low amounts of fatty breast tissue—should always get regular mammograms, which is the most useful tool for breast cancer detection. However, dense breasts can make it more difficult for radiologists to interpret mammograms. The fatty breast tissue appears dark on mammograms, while both dense tissue and some breast abnormalities appear white on a mammogram, increasing the risk that cancer may be missed.

To address this issue, many experts advise women with dense breasts to get supplemental screenings, such as a breast ultrasound or MRI. While these are more sensitive than mammograms, they can increase false positives.

Medical professional organizations have not issued supplemental screening guidelines for women with dense breasts, citing insufficient evidence assessing the benefits and harms of supplemental screening. Without such guidelines, women who have dense breasts and require supplemental screening may have to pay for these additional tests out of pocket, depending on whether they live in a state that requires insurers to cover them.

“Women with dense breasts are in a grey area and need better options for screening,” Dr. El-Ashry said. “This is why BCRF is supporting research to test new screening technologies, including those like contrast-enhanced mammography that augment existing screening tools and could be deployed widely and affordably.”

Can I get mammograms during pregnancy or while I’m nursing?

It is generally considered safe to have mammograms during pregnancy or while breastfeeding. While mammograms do expose you to radiation, the amount is small and focused on your breasts, so most of it doesn’t reach other body parts. (Radiation does not affect breast milk). Plus, the technician will place a lead shield on the lower part of your stomach during your screening to provide extra protection for the fetus.

That said, experts aren’t 100 percent certain about the effects that a small dose of radiation may have on a fetus. Your doctor may advise you to get a breast ultrasound, which uses sound waves rather than radiation to capture images of breast tissue. Ultrasound is already preferred for women who are pregnant or nursing because both increase breast density, making it harder to detect suspicious areas mammograms during pregnancy.

What type of mammogram should I get? 2D vs. 3D Mammograms

There are two types of screening mammograms: standard 2D digital mammography and 3D digital mammography, a newer technique also known as 3D tomosynthesis, digital breast tomosynthesis, or 3D breast imaging. These may also be used for diagnostic mammograms.

In 2D digital mammography, the technician takes images of the breasts from two angles, one from top to bottom and the other from side to side. When you get a 3D mammography, multiple images are taken from several angles to create a 3D image that enables radiologists to evaluate breast tissue more clearly by layer.

While 3D mammography might seem superior to 2D mammography, it has advantages and disadvantages. 3D mammograms provide better visibility of cancer, and there is a reduced rate of follow-up imaging compared to 2D mammograms. But a 3D mammogram exposes you to a higher dose of radiation, and it may miss microcalcifications that, while common and often harmless, can be a sign of breast cancer. 3D mammograms also often cost more than 2D mammograms, though most health insurance companies cover them. In some states, insurers are required to do so.

So, between 2D vs. 3D mammograms, which type of mammogram should you get? Currently, there are no firm recommendations from medical professional organizations. For example, ACS guidelines say women should be able to choose whether they get 2D or 3D mammograms, while USPSTF simply states that both 2D and 3D mammography are effective screening techniques. ASBS goes a step further, declaring 3D mammography the preferred modality.

Ultimately, you should talk with your doctor about the appropriate technique for you. Most women get 2D mammograms, but 3D mammography may be recommended if you have dense breasts or are at high risk of breast cancer since it’s more effective for these groups.

The bottom line

Ultimately, decisions about when to start mammograms, how you should get a mammogram, and more should be made in conversation with your doctor and based on your personal risk of breast cancer. If you’re under 40, make sure you’ve had a breast cancer risk assessment done, and if you’re 40 or older and haven’t started screening, ask your doctor when you should.