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Breast Cancer Screening and Mammograms: Answers to Common Questions

By BCRF | May 17, 2023

What to know about breast cancer screening guidelines, types of tools, dense breasts, research, and more

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 in the general population, and, looking ahead, researchers continue to explore ways to improve mammography and screening technologies.

Here, we answer common questions about mammography and breast cancer screening, plus how BCRF researchers are advancing this technology.

What is a mammogram?

A mammogram is an X-ray of the breast made by using low doses of radiation to create an image. 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 screening tools?

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, digital mammography emerged—a technique where images are stored as a digital computer image—and was termed 2D digital mammography. Today, film and digital images are reviewed by a radiologist, but digital computer mammography provides several advantages: image quality is better and easier to control; computer images allow a radiologist to magnify areas of concern; and images from subsequent mammograms are easier to compare.

The newest technology 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 “slice” at a time digitally—thereby deciphering 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—that is, the breast is compressed to help capture the complete breast in both techniques—3D imaging does mean more radiation (although well within the FDA-approved limits), is more expensive, and is not yet widely available.

Whole breast ultrasound (WBUS) or magnetic resonance imaging (MRI) are other breast imaging tools that 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 and MRI uses magnets to produce images of the whole breast.

What is a diagnostic mammogram versus a screening mammogram?

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 how often and at what age a woman should start getting 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 confirm 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 your care team to reposition your breast if necessary to get more accurate views of the suspect area. This means that a woman will know, in real time, if a follow-up biopsy is recommended.

WBUS and MRI may also be used as a follow-up when mammography has yielded abnormal results. While WBUS and MRI are safe and provide valuable information, they both 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.

When is WBUS necessary?

  • If you have a lump in your breast, WBUS may be used to determine if it’s fluid-filled, solid, or a combination; the latter two would be cause for more tests
  • If you have other persistent symptoms such as redness, pain, or swelling
  • If you have dense breast tissue, WBUS can provide more detail than a mammogram
  • If you have silicone implants, WBUS may be recommended since mammograms may not detect small lumps obscured by an implant

And MRI?

Unlike WBUS, MRI may be used with a contrast dye that makes it easier to see breast abnormalities. It is typically only used under certain circumstances:

  • As a screening tool for women who are at an increased risk of breast cancer (such as those who are BRCA gene carriers or whose family members are) and/or women with a family history of breast cancer. Note, for these women, clinicians may recommend alternating between mammograms and either MRIs or WBUS as part of their screening routine.
  • As a follow up to mammography to detect breast cancer

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

Breasts are made up of a combination of epithelial tissue that form the ducts and 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, and breast density decreases with age, with 40 percent of women over the age of 40 still having dense breasts.

Density can’t be determined from a physical exam; a mammogram is the only way to determine the composition of your breast/breast density. In March 2023, the FDA issued a ruling requiring mammography clinics to disclose a woman’s dense breast status and standardized how they do so (previously, disclosures varied by state with 12 not requiring any notification at all.)

Fatty tissue and dense tissue look different on a mammogram: X-rays pass through fatty tissue more easily and appear black in the image 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 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 WBUS or MRI in addition to a mammogram.

Dense Breast Tissue: What It Means And What To Know

When should women get mammograms?

Most organizations recommend breast cancer 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 May 2023, the influential U.S. Preventive Services Task Force (USPSTF) announced it was revising its previous guidelines to recommend women with an average breast cancer risk receive biannual mammograms beginning at age 40 instead of 50. The change comes as diagnoses are on the rise in women under 50. The task force emphasized that Black women especially be screened at 40 because they’re more likely to be diagnosed at younger ages and with aggressive breast cancers, leading to worse outcomes. This change highlighted 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 screening routine for their personal circumstances with their doctors to take into account 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 40-49 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 continued to recommend screening every other year. Some agencies—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, and all options should be considered in consult with your doctor.

What are the risks associated with breast cancer screening?

Technical advances in mammography machines allow the use of low doses of radiation to 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.

Are mammograms painful?

Every woman’s tolerance is different, but mammograms are generally not painful. Most women experience mild discomfort when the mammography machine compresses their breasts. Since the procedure is quick—usually less than 15 minutes—this is a bearable discomfort for most women.

What do I need to know about getting a mammogram after a COVID-19 vaccine?

Aim to have your mammogram before the COVID-19 vaccine or four to six weeks after the last dose. The COVID-19 vaccine, like other vaccines, can cause an enlargement of lymph nodes (axillary adenopathy) near the breast and under the arm. This is a normal and temporary reaction to a vaccine that mobilizes your immune system by signaling your lymph nodes to produce antibodies to fight the foreign substance. But enlarged lymph nodes could lead to false positives on a mammogram. So, it’s best to allow the lymph nodes time to return to normal size before your mammogram. But if it’s time for your mammogram, don’t delay—and be sure to let your care team know when you were vaccinated.

RELATED: COVID-19 and Breast Cancer: What Patients Need to Know

A comprehensive study has found that, alarmingly, breast cancer screening decreased globally by 46.7 percent (and by 44.6 percent in the U.S. and Canada) from January to March 2020 at the beginning of the COVID-19 pandemic. Screening rates rebounded in April 2020 and recovered by May 2020. However, this is still concerning for its implications on cancer mortality: Any delays in detection could result in a more later-stage diagnosis. COVID-19’s full effects remain to be seen but these data underscore the importance of regular screening.

Do mammograms save lives?

Yes, mammograms undoubtedly save lives because they help detect breast cancer early. Early detection—finding the 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 40 percent decline in the breast cancer mortality rate in the last 30 years, in part due to earlier and better detection methods. Today, a woman has a near 100 percent chance of survival (at five years) when breast cancer has been caught early (i.e., localized disease). And for those detected at advanced stages (i.e., stage 4), survival rates at five years are about 28 percent.

RELATED: Why We Must Improve Breast Cancer Screening

In a study published in Radiology, researchers looked at the impact of regular 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 screening’s benefits for detecting breast cancer and improving mortality.

How will research improve breast cancer screening?

Investigators are constantly working to improve mammography techniques, image quality, and methods to interpret results. 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 to improve and enhance breast cancer screening.

CEM and CESM holds 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, this technology is a simple and quick procedure but 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, which capitalizes on the power of computer analysis, as an efficient tool for helping 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 that compares MRI screening with 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 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 screening is the most important factor influencing outcome of a breast cancer diagnosis.

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.

Selected References:

ACP issues guidance statement for breast cancer screening of average-risk women with no symptoms | ACP Newsroom | ACP. (2019, April 19). American College of Physicians. Retrieved December 2020, from

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Helvie, M. A., & Bevers, T. B. (2018). Screening Mammography for Average-Risk Women: The Controversy and NCCN’s Position. Journal of the National Comprehensive Cancer Network, 16(11), 1398–1404.

Kuhl, C. K., Lehman, C., & Bedrosian, I. (2020). Imaging in Locoregional Management of Breast Cancer. Journal of Clinical Oncology, 38(20), 2351–2361.

Monticciolo, D. L., Newell, M. S., Moy, L., Niell, B., Monsees, B., & Sickles, E. A. (2018). Breast Cancer Screening in Women at Higher-Than-Average Risk: Recommendations From the ACR. Journal of the American College of Radiology, 15(3), 408–414.

Sharma, K.P., Grosse, S.D., Maciosek, M.V., Joseph, D., Roy, K., Richardson, L.C., & Jaffe, H. (2020, October). Preventing Breast, Cervical, and Colorectal Cancer Deaths: Assessing the Impact of Increased Screening. Preventing Chronic Disease: Public Health Research, Practice, and Policy 17, E123.

Teglia, F., Angelini, M., Astolfi, L., Casolari, G., & Boffetta, P. (2022, September 1). Global Association of COVID-19 Pandemic Measures With Cancer Screening. JAMA Oncology, 8(9), 1287.

Vourtsis, A., & Berg, W. A. (2018). Breast density implications and supplemental screening. European Radiology, 29(4), 1762–1777.