When Should You Get a Mammogram?

Editors note: This story originally ran May 15, 2023 and was updated May 2, 2024. 

Breast cancer screening saves lives, but when to start screening hasn’t always been clear. While the age to start has been debated in recent years, most experts now agree that women should start having mammograms at age 40.

“Starting mammograms at age 40 saves the most lives,” says UNC Health radiologist Genevieve Woodard, MD, PhD, chief of the UNC Breast Imaging Division.

Mammograms find cancer in its early stages, when it is most treatable. Approximately 1 in 8 women will be diagnosed with invasive breast cancer in her lifetime and 1 in 39 women will die from breast cancer, making it the second-leading cause of cancer death in women.

“Screening for breast cancer reduces the death rate from breast cancer,” Dr. Woodard says. “Seventy percent of women who get breast cancer have no risk factors, including family history. Therefore, all women should start screening mammography at age 40, but some women may need to start earlier and may need additional screening exams.”

If breast cancer has not spread to other organs or tissue in the body, then 99 percent of women survive for at least five years after diagnosis.

When to Start Getting Mammograms

The greatest risk factor for developing breast cancer is age. The greatest number of breast cancer cases are found in women ages 50 to 80, although 1 in 6 breast cancers occur in women in their 40s.

Leading medical organizations, including the American College of Radiology, the Society of Breast Imaging, and now the U.S. Preventive Services Task Force recommend screening mammograms starting at age 40.

Experts agree that women with risk factors for developing breast cancer should start mammograms early. This advice includes Black women, who have a lower rate of breast cancer (about 128 per 100,000 women) than white women (about 134 per 100,000), but their death rate from breast cancer is 40 percent higher. Breast cancer is the leading cause of cancer deaths among Black and Hispanic women. This is due in part to a higher risk from triple-negative breast cancer and later diagnosis, according to the American Cancer Society.

Another group at risk is transgender women assigned male sex at birth and exposed to feminizing hormones, and transgender men assigned female sex at birth who have breast tissue present.

If you are pregnant or lactating, you can still get a mammogram, but unless you are at high risk or have symptoms that need to be diagnosed, you might want to wait until after delivery, Dr. Woodard says.   There are minor risks of radiation from X-rays, even if most of your body is covered with a lead apron. When you are pregnant and lactating, your breasts are denser, which will make the mammogram harder to read.

No matter what your situation, talk to your doctor about your risk factors.

“By at least age 25, all women should have a discussion with their provider about their risk of breast cancer,” Dr. Woodard says.

Women should continue getting mammograms as long as they are in good health and expect to live another 10 years or more, she says.

Types of Breast Cancer Screening Tests

Mammograms are X-rays of your breasts. As you stand before the mammogram machine, a technologist will place your breast flat on a plate or platform. Another plate will press down on your breast from above and the side, flattening your breast tissue to allow X-rays to produce a clearer image of breast tissue. This process may be uncomfortable but is not painful and lasts only a few minutes.

Tomosynthesis, or 3D mammograms, are becoming more widely used, Dr. Woodard says. They provide a more detailed look at the breasts than the traditional 2D images, and more insurance companies are covering the cost.

“3D mammograms have been proven to have higher sensitivity, meaning we find more and smaller breast cancers,” she says. “And they have the added benefit of reducing false positives, which reduces the need for more testing or biopsy for things that are not breast cancer. It’s also great for dense breasts, giving us a better view of the tissue.”

For people at high risk of breast cancer, doctors may also advise a breast MRI, which uses magnets and intravenous contrast to get information that a mammogram may not pick up. Mammograms reveal information MRIs may not, so an MRI doesn’t replace a mammogram but is supplemental.

The Role of Breast Self-Exams

Examining your own breasts once a month lets you know what is normal for you. You can get familiar with how your breasts feel and look, and you will more easily recognize changes, such as lumps, pain or changes in size. Report those changes to your doctor. Similar exams are often done in the clinic by a doctor or other healthcare provider.

“Know what’s normal for you,” Dr. Woodard says. “For example, if you perform a self-exam consistently, you’ll know if you have a little lump that comes and goes with your menstrual cycle, or if your nipple looks different, or one breast is unusually larger or smaller than the other.”

If you have concerns about your breast health or questions about cancer screening, talk to your doctor or find one near you.