Mammograms: Everything You Need to Know

What is a mammogram? What are the different types of mammograms? BCRF answers common questions about this breast cancer screening tool

Did you know that some form of mammography has been around since the early 1900s? In 1913, German surgeon Albert Salomon first used X-rays to identify differences between healthy and diseased breast tissues. Steady advancements in breast imaging continued through the first half of the 20th century, and by the 1960s, mammography had become a widely used diagnostic tool. Today, mammography is the gold standard in breast cancer screening, and, looking ahead, researchers continue to explore ways to improve mammography and other breast cancer screening methods.

Here, we answer common questions about mammography and breast cancer screening including: Are mammograms safe? What do I need to know about breast cancer screening methods? Plus, we dive into how BCRF researchers are advancing this lifesaving technology.

What is a mammogram?

A mammogram is an X-ray image of the breast made using low doses of radiation. Doctors analyze these X-rays for masses or microcalcifications that may indicate the presence of breast cancer. Mammograms are used for diagnosis and screening to detect breast cancer early, when it’s most easily treated.

What are the different types of mammograms and breast cancer screening methods?

Most women receive the standard-of-care technique called 2D mammography, where two X-ray images of a person’s breast are taken (one from the top and one from the side). In the first years of mammography, X-ray images were saved on film. As technology advanced, 2D digital mammography emerged—a technique where images are stored as a digital computer image. Today, a radiologist reviews both film and digital images, but digital computer mammography provides several advantages: image quality is better and easier to control; radiologists can magnify areas of concern; and images from subsequent mammograms are easier to compare.

One of the newest types of mammograms is 3D digital mammography, where a technician takes multiple images from different angles in an arc over the breast. These images are computer synthesized to create a three-dimensional reproduction of a person’s breast. Radiologists can then incrementally assess breast tissue one digital “slice” at a time, thereby seeing more detail than previously possible. Also known as 3D tomosynthesis, digital breast tomosynthesis, or 3D breast imaging, this technique has been shown to reduce the rate of false positives and call-back appointments. While the patient experience is similar, 3D imaging does mean more radiation (although well within the FDA-approved limits), is more expensive, and is not yet widely available.

Other breast imaging tools, such as whole breast ultrasound (WBUS) and magnetic resonance imaging (MRI), can accompany mammography in certain circumstances. Both tools reveal information about the structure of the breast and surrounding areas without the use of X-rays. WBUS uses sound waves to produce images of the whole breast whereas MRI uses magnets.

What is a diagnostic mammogram?

Wondering about the differences between screening vs. diagnostic mammograms? A screening mammogram is recommended as routine medical care for healthy women, particularly those who don’t have symptoms or a known predisposition or elevated genetic risk. (Keep reading for information on at what age and how often a woman should get screened.) Regular screening mammograms help doctors identify changes in your breast from year to year that may be a cause for concern. They are usually performed quickly with results sent to you within a week or two.

In contrast, a diagnostic mammogram is used to evaluate a suspicious finding. It is basically the same procedure as a screening mammogram, but more images are taken in each position (from the top and from the side), allowing the technologist to reposition your breast if necessary to get more accurate views of the suspect area. This means that a woman will possibly know, in real time, if a follow-up biopsy is recommended.

WBUS or MRI may also be used as a follow-up when mammography has yielded abnormal results. It is important to note that both techniques result in higher rates of false-positives and cost more than standard-of-care mammography, and MRI may not be readily available in all areas. They also do not take the place of a mammogram. However, these supplemental tests are safe and provide valuable information.

What are dense breasts, and how do they affect breast cancer screening methods and mammography?

Breasts are made up of a combination of different tissues. Epithelial tissue forms the ducts while the rest of the breast is a mix of fatty, glandular, and fibrous tissue. Having dense breasts means that you have a low amount of fatty tissue compared to glandular and fibrous tissues. Density varies from individual to individual but generally, younger women tend to have dense breasts. Breast density decreases with age, with 40 percent of women having dense breasts after age 40.

Fatty tissue and dense tissue look different on a mammogram: Fatty tissue appears black on the image because X-rays pass through it more easily, whereas dense tissue appears white. Since calcifications, masses, and tumors also appear white on the image, having dense breasts can make it more difficult to detect cancer and discern changes in your breast. Women with dense breasts also have a higher risk for breast cancer compared to women with less-dense tissue. The reason for this is unclear. Therefore, for most women with dense breasts, doctors recommend breast cancer screening methods like WBUS or MRI in addition to a mammogram.

A mammogram is the only way to determine the composition of your breasts and breast density; a physical exam is not enough. In March 2023, the FDA issued a ruling requiring mammography clinics to disclose a woman’s dense breast status. Previously, disclosures about breast density varied by state with 12 not requiring any notification at all. These new regulations, which went into effect on September 10, 2024, seek to empower patients with the information they need to make informed decisions about breast cancer screening. You can now find your status on your mammography report.

When should women get mammograms?

Most breast cancer/mammogram screening guidelines recommend screening beginning at age 40 but differ on frequency (annual versus biannual screening). Discrepancies such as these partially reflect the field’s competing focuses on increasing early detection versus reducing the rate of false positives and overtreatment.

In April 2024, the influential U.S. Preventive Services Task Force (USPSTF) finalized new guidelines for breast cancer screening. It revised its previous recommendation, which had stated that women with an average breast cancer risk receive biannual mammograms beginning at age 50. The group now recommends biannual screening for women at average risk beginning at age 40. The change comes as diagnoses are on the rise in women under 50. The task force emphasized that Black women especially should start breast cancer screening at 40 because they’re more likely to be diagnosed at younger ages and with aggressive breast cancers, leading to worse outcomes. This change highlights the continued need to personalize screening.

“A one-size-fits-all approach to screening recommendations creates vulnerable populations,” said BCRF Chief Scientific Officer Dr. Dorraya El-Ashry. “Personalized, risk-based screening should be the ultimate goal. Research can and is helping us identify and even quantify that risk, better informing decisions around screening.”

Everyone should discuss the best breast cancer screening routine for their personal circumstances with their doctors, taking into account their family history of breast cancer, genetic makeup, and other factors.

How often should you get a mammogram?

Most commonly, breast cancer screening via mammography is recommended yearly beginning at 40. However, the American College of Physicians (ACP) has stated that women between 50-74 with an average risk of breast cancer (based on family history, genetics, etc.) can opt to have screening mammography every two years, and the recent USPSTF draft guidelines continue to recommend screening every other year.

The American College of Obstetricians and Gynecologists (ACOG) and the American College of Radiology (ACR) have concluded that annual screening should continue for women 50–74. The American Cancer Society (ACS) concurs but adds that women 55–74 can opt to have screening every two years.

The bottom line is that these are guidelines. You should discuss all breast cancer screening methods and guidelines with your doctor.

Are there any risks associated with mammograms?

Some of the most common questions women have about breast cancer screening are about safety: Are mammograms safe? Are there any mammogram risks? Technical advances in mammography machines mean that low doses of radiation now yield high-quality images. The Mammography Quality Standards Act (MQSA) was developed to ensure that this radiation dose is as low as possible. Therefore, getting a mammogram is relatively safe. In fact, the ACS estimates that a woman receives less radiation from a mammogram of both breasts than the amount she receives from her natural surroundings (background radiation) over seven weeks.

While your doctor may delay your mammogram if you are pregnant and at a low risk for breast cancer, there is no evidence to suggest that a mammogram is harmful to a fetus.

What does a mammogram involve?

Before your mammogram, you’ll be asked to undress from the waist up and remove any jewelry, lotion, or deodorant, as these can interfere with the X-ray image. A technologist will position each breast on a flat surface and gently compress it with a plastic plate to evenly spread the tissue. This compression may feel uncomfortable, but it lasts only a few seconds per image. You can eat, drink, and take medications as normal before and after the appointment. To make the experience more comfortable, consider scheduling your mammogram a week after your period, when your breasts are less tender.

How long does a mammogram take?

Generally, a mammogram takes between 15 to 30 minutes—and even as little as 10 minutes. Your breasts will only be compressed for a few seconds at a time.

Do mammograms save lives?

Yes, mammograms undoubtedly save lives because they help detect breast cancer early. Early detection—finding breast cancer before it has a chance to spread—is the key to a good prognosis from a breast cancer diagnosis. There has been a more than 40 percent decline in the breast cancer mortality rate in the last 30 years, in part due to earlier and better breast cancer screening methods. Today, a woman has a near 100 percent chance of survival (at five years) when breast cancer has been caught early, when it is still confined to the breast (localized disease). For those with advanced cancer (stage 4), five-year survival rates are about 31 percent.

In a study published in Radiology, researchers looked at the impact of regular breast cancer screenings and found that women who had mammograms in each of the two years preceding a diagnosis were 50 percent less likely to die than those who had not. This large study further emphasized breast cancer screening’s benefits for detecting breast cancer and reducing mortality rates.

How will research improve mammograms?

In the U.S., breast cancer is the leading cause of cancer-related death and the most commonly diagnosed cancer in women. More than 330,000 women are diagnosed with breast cancer each year, and one in eight women will develop the disease over their lifetime. Early detection through regular breast cancer screening is the most important factor influencing the outcome of a breast cancer diagnosis.

Investigators are constantly working to improve mammograms and other breast cancer screening methods, image quality, and interpretation. In particular, BCRF-funded researchers are testing new technologies — including contrast-enhanced spectral mammography (CESM), artificial intelligence (AI) and contrast-enhanced ultrasound technology (CEM), and AI plus machine learning (technology that enables computers to solve more intricate problems) — to improve and enhance breast cancer screening.

CEM and CESM hold particular promise for screening women with dense breasts. In addition to yielding traditional mammography images, CESM detects blood flow patterns, which can indicate breast cancer. As with traditional mammography, it is a simple and quick procedure, but it is better able to detect early breast cancer in dense breasts and is more precise than traditional mammography, resulting in fewer false positive results.

Researchers are assessing AI as an efficient tool to help radiologists interpret mammograms. Thus far, AI has provided a distinct advantage in accurately detecting breast cancer earlier and reducing the rate of false positives and unnecessary procedures. In combination with machine learning—technology that enables computers to solve more intricate problems—BCRF researchers are analyzing mammograms from tens of thousands of patients and correlating the results with patient data (such as reproductive and genetic factors and biomarker data) to develop better breast cancer risk prediction models.

BCRF also supports an AI screening project spearheaded by Drs. Regina Barzilay and Adam Yala that compares highly precise MRI screening versus a unique model called MIRAI, which combines AI and machine learning to analyze mammograms. In initial studies, MIRAI shows great promise for detecting breast cancer earlier, more efficiently, and at less cost than MRI. Researchers are now testing MIRAI more broadly.

AI is an exciting technique with broad implications for breast cancer screening and has the potential to predict, with high sensitivity and specificity, those patients most likely to develop breast cancer. In fact, BCRF support has enabled researchers to develop a novel AI-driven tool that can determine a woman’s 5-year breast cancer risk from a single mammogram. The tool, Clairity Breast, received de novo FDA-approval, the first of its kind AI tool to be cleared for risk assessment.

Research is rapidly advancing mammography’s power to deliver personalized, targeted screening practices that will improve outcomes for high-risk populations while reducing unnecessary procedures and treatment. BCRF is proud to support this and other groundbreaking science that will personalize care, help save lives, and put an end to breast cancer.