Mammography
Mammography is the process of using low-energy X-rays to examine the human breast for diagnosis and screening. The goal of mammography is the early detection of breast cancer, typically through detection of characteristic masses, microcalcifications, asymmetries, and distortions.
As with all X-rays, mammograms use doses of ionizing radiation to create images. These images are then analyzed for abnormal findings. It is usual to employ lower-energy X-rays, typically Mo and Rh than those used for radiography of bones. Mammography may be 2D or 3D, depending on the available equipment or purpose of the examination. Ultrasound, ductography, positron emission mammography, and magnetic resonance imaging are adjuncts to mammography. Ultrasound is typically used for further evaluation of masses found on mammography or palpable masses that may or may not be seen on mammograms. Ductograms are still used in some institutions for evaluation of bloody nipple discharge when a mammogram is non-diagnostic. MRI can be useful for the screening of high-risk patients, for further evaluation of questionable findings or symptoms, as well as for pre-surgical evaluation of patients with known breast cancer, in order to detect additional lesions that might change the surgical approach.
In 2023, the U.S. Preventive Services Task Force issued a draft recommendation statement that all women should receive a screening mammography every two years from age 40 to 74. The American College of Radiology, Society of Breast Imaging, and American Cancer Society recommend yearly screening mammography starting at age 40. The Canadian Task Force on Preventive Health Care and the European Cancer Observatory recommend mammography every 2 to 3 years between ages 50 and 69. These task force reports point out that in addition to unnecessary surgery and anxiety, the risks of more frequent mammograms include a small but significant increase in breast cancer induced by radiation. Additionally, mammograms should not be performed with increased frequency in patients undergoing breast surgery, including breast enlargement, mastopexy, and breast reduction.
Types
Digital
Digital mammography is a specialized form of mammography that uses digital receptors and computers instead of X-ray film to help examine breast tissue for breast cancer. The electrical signals can be read on computer screens, permitting more manipulation of images to allow radiologists to view the results more clearly. The standard digital mammography is "full field", in which the entire breast is imaged in a single view. Digital mammography can also include the use of "spot views", in which a paddle is used to further compress areas of concern.Digital mammography is also utilized in stereotactic biopsy. Breast biopsy may also be performed using a different modality, such as ultrasound or magnetic resonance imaging.
While radiologists had hoped for more marked improvement, the effectiveness of digital mammography was found comparable to traditional X-ray methods in 2004, though there may be reduced radiation with the technique and it may lead to fewer retests. Specifically, it performs no better than film for post-menopausal women, who represent more than three-quarters of women with breast cancer. The U.S. Preventive Services Task Force concluded that there was insufficient evidence to recommend for or against digital mammography over basic film mammography for breast cancer screening.
Digital mammography is a NASA spin-off, utilizing technology developed for the Hubble Space Telescope. As of 2022, over 99% of certified mammography centers in the United States screening centers use digital mammography. Globally, systems by Fujifilm Corporation are the most widely used. In the United States, GE's digital imaging units typically cost US$300,000 to $500,000, far more than film-based imaging systems. Costs may decline as GE begins to compete with the less expensive Fuji systems.
3D mammography
, also known as digital breast tomosynthesis, tomosynthesis, and 3D breast imaging, is a mammogram technology that creates a 3D view of the breast using X-rays from different angles. Supplementing standard 2D mammography with DBT has been shown to improve cancer detection. Cost effectiveness is unclear as of 2016. Another concern is that it more than doubles the radiation exposure.Contrast-enhanced mammography
Contrast-enhanced mammography is an advanced imaging technique that employs iodinated contrast agents to visualize breast neovascularization, functioning similarly to magnetic resonance imaging. Tumor-associated angiogenesis often results in leaky blood vessels, allowing contrast material to accumulate within the tumor tissue and produce an iodine-enhanced image. This enhances the visibility of malignancies that might otherwise be obscured by dense breast tissue. Contrast-enhanced mammography is also referred to as contrast-enhanced spectral mammography, contrast-enhanced digital mammography, or contrast-enhanced dual-energy mammography.A large randomized controlled trial published in The Lancet in 2025 found that contrast-enhanced mammography detects significantly more invasive breast cancers in women with dense breast tissue than standard mammography or ultrasound. Conducted across 10 U.K. screening sites with over 9,000 participants, the study reported that contrast-enhanced mammography identified 15.7 invasive cancers per 1,000 exams, compared to 4.2 for ultrasound and 15 for MRI, with no statistically significant difference between Contrast-enhanced mammography and MRI. CEM was also found to be more cost-effective and accessible than MRI. Advocates suggest contrast-enhanced mammography could improve early detection and outcomes for women with dense breasts, but acknowledge risks of overdiagnosis.
Photon counting
Photon-counting mammography was introduced commercially in 2003 and was shown to reduce the X-ray dose to the patient by approximately 40% compared to conventional methods while maintaining image quality at an equal or higher level. The technology was subsequently developed to enable spectral imaging with the possibility to further improve image quality, to distinguish between different tissue types, and to measure breast density.Galactography
A galactography is a now infrequently used type of mammography used to visualize the milk ducts. Prior to the mammography itself, a radiopaque substance is injected into the duct system. This test is indicated when nipple discharge exists.Medical uses
Mammography can detect cancer early when it's most treatable and can be treated less invasively.According to National Cancer Institute data, since mammography screening became widespread in the mid-1980s, the U.S. breast cancer death rate, unchanged for the previous 50 years, has dropped well over 30 percent. In European countries like Denmark and Sweden, where mammography screening programs are more organized, the breast cancer death rate has been cut almost in half over the last 20 years.
Mammography screening cuts the risk of dying from breast cancer nearly in half. A recent study published in Cancer showed that more than 70 percent of the women who died from breast cancer in their 40s at major Harvard teaching hospitals were among the 20 percent of women who were not being screened. Some scientific studies have shown that the most lives are saved by screening beginning at age 40.
A recent study in the British Medical Journal shows that early detection of breast cancer – as with mammography – significantly improves breast cancer survival.
The benefits of mammography screening at decreasing breast cancer mortality in randomized trials are not found in observational studies performed long after implementation of breast cancer screening programs
When to start screening
In 2014, the Surveillance, Epidemiology, and End Results Program of the National Institutes of Health reported the occurrence rates of breast cancer based on 1000 women in different age groups. In the 40–44 age group, the incidence was 1.5 and in the 45–49 age group, the incidence was 2.3. In the older age groups, the incidence was 2.7 in the 50–54 age group and 3.2 in the 55–59 age group.While screening between ages 40 and 50 is somewhat controversial, the preponderance of the evidence indicates that there is a benefit in terms of early detection. Currently, the American Cancer Society, the American Congress of Obstetricians and Gynecologists, the American College of Radiology, and the Society of Breast Imaging encourage annual mammograms beginning at age 40.
The National Cancer Institute encourages mammograms every one to two years for women ages 40 to 49. In 2023, United States Preventive Services Task Force revised the recommendation that women and transgender men undergo biennial mammograms starting at the age of 40, rather than the previously suggested age of 50. This adjustment is prompted by the increasing incidence of breast cancer in the 40 to 49 age group over the past decade.
In contrast, the American College of Physicians, a large internal medicine group, has recently encouraged individualized screening plans as opposed to wholesale biannual screening of women aged 40 to 49. The American Cancer Society recommendations for women at average risk for breast cancer is a yearly mammogram from age 45 to 54 with an optional yearly mammogram from age 40 to 44.
Screening for high-risk population
Women who are at high risk for early-onset breast cancer have separate recommendations for screening. These include those who:- Have a known BRCA1 or BRCA2 gene mutation.
- Have a 1st-degree relative, 2nd-degree relative, or 3rd-degree relative with a known BRCA1 or BRCA2 gene mutation.
- Have a lifetime risk of breast cancer >20% according to risk assessment tools
- History of radiation therapy to chest between 10 and 30 years of age
- Have or has a 1st-degree relative with a genetic syndrome including Li-Fraumeni syndrome, Cowden syndrome, or Bannayan-Riley-Ruvalcaba syndrome
The National Comprehensive Cancer Network advocates screening for women who possess a BRCA1 or BRCA2 mutation or have a first-degree relative with such a mutation, even in the absence of the patient being tested for BRCA1/2 mutations. For women at high risk, the network recommends undergoing an annual mammogram and breast MRI between the ages of 25 and 40, considering the specific gene mutation type or the youngest age of breast cancer occurrence in the family. Additionally, the network suggests that high-risk women undergo clinical breast exams every 6 to 12 months starting at age 25. These individuals should also engage in discussions with healthcare providers to assess the advantages and disadvantages of 3D mammography and acquire knowledge on detecting changes in their breasts.