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Mammography (also called mastography; DICOM modality: MG) is the process of using low-energy (usually around 30 Peak kilovoltage) 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 (K-shell X-ray energies of 17.5 and 19.6 keV) and Rh (20.2 and 22.7 keV) than those used for radiography of . Mammography may be 2D or 3D (tomosynthesis), depending on the available equipment or purpose of the examination. Ultrasound, ductography, positron emission mammography (PEM), and magnetic resonance imaging (MRI) 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 the 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 (for example, from breast-conserving lumpectomy to mastectomy).
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 (2012) and the European Cancer Observatory (2011) 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.
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 (MRI).
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 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 Fujifilm systems.
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.
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. (Otto et al) 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 The BMJ 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 (for instance, Bleyer et al.)
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 (ACOG), 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 (USPSTF) 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.
The American College of Radiology recommends these individuals to get annual mammography starting at the age of 30. Those with a history of chest radiation therapy before age 30 should start annually at age 25 of 8 years after their latest therapy (whichever is latest). The American Cancer Society also recommends women at high risk should get a mammogram and breast MRI every year beginning at age 30 or an age recommended by their healthcare provider.
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.
Until some years ago, mammography was typically performed with screen-film cassettes. Today, mammography is undergoing transition to digital detectors, known as digital mammography or Full Field Digital Mammography (FFDM). The first FFDM system was approved by the FDA in the U.S. in 2000. This progress is occurring some years later than in general radiology. This is due to several factors:
As of March 1, 2010, 62% of facilities in the United States and its territories have at least one FFDM unit. (The FDA includes computed radiography units in this figure.)
Tomosynthesis, otherwise known as 3D mammography, was first introduced in clinical trials in 2008 and has been Medicare-approved in the United States since 2015. As of 2023, 3D mammography has become widely available in the US and has been shown to have improved sensitivity and specificity over 2D mammography.
Mammograms are either looked at by one (single reading) or two (double reading) trained professionals: these film readers are generally , but may also be radiographers, , or breast clinicians (non-radiologist physicians specializing in breast disease).
Double reading significantly improves the sensitivity and specificity of the procedure, and is standard practice in the United Kingdom, but not in the United States as it is not reimbursed by Medicare or private health insurance. This is despite multiple trials showing increased accuracy of detection and improved patient outcomes for both prevalence and mortality rate when double reading is employed. Clinical decision support systems may be used with digital mammography (or digitized images from analogue mammography), but studies suggest these approaches do not significantly improve performance or provide only a small improvement.
The use of language with BI-RADS is extremely precise, with a limited set of permissible adjectives for lesion margins, shape and internal density, each of which carries a different prognostic significance. Margins of a lesion, for example, can only be described as circumscribed, obscured, micropapillary, indistinct or stellate. Similarly, shape can only be round, oval or irregular. Each of these agreed upon adjectives is referred to as a "descriptor" in the BI-RADS lexicon, with specific positive and negative predictive values for breast cancer with each word. Additionally, each BI-RADS category corresponds with a probability of cancer. This fastiduous attention to semantics with BI-RADS allows for standardization of cancer detection across different treatment centers and imaging modalities.
After describing the findings, the radiologist provides a final assessment ranging from 0 to 6:
BI-RADS 3, 4 and 5 assessments on screening mammograms require further investigation with a second "diagnostic" study. The latter is a more detailed mammogram that allows dedicated attention to the abnormal finding with additional maneuvers such as magnification, rolling of breast tissue or exaggerated positioning. There may also be imaging with ultrasound at this time, which carries its own parallel BI-RADS lexicon. Suspicious lesions are then biopsy with local anesthesia or proceed straight to surgery depending on their staging. Biopsy can be done with the help of x-rays or ultrasound, depending on which imaging modality shows the lesion best.
In the UK mammograms are scored on a scale from 1–5 (1 = normal, 2 = benign, 3 = indeterminate, 4 = suspicious of malignancy, 5 = malignant). Evidence suggests that accounting for genetic risk, factors improve breast cancer risk prediction.
In 1913, German surgeon Albert Salomon performed a mammography study on 3,000 mastectomies, comparing X-rays of the breasts to the actual removed tissue, observing specifically microcalcifications. By doing so, he was able to establish the difference as seen on an X-ray image between cancerous and non-cancerous tumors in the breast. Salomon's mammographs provided substantial information about the spread of tumors and their borders. (2025). 9783540219279, Springer. ISBN 9783540219279
In 1930, American physician and radiologist Stafford L. Warren published "A Roentgenologic Study of the Breast", a study where he produced stereoscopic X-rays images to track changes in breast tissue as a result of pregnancy and mastitis. (2025). 9780721695631, Saunders. ISBN 9780721695631 In 119 women who subsequently underwent surgery, he correctly found breast cancer in 54 out of 58 cases.
As early as 1937, Jacob Gershon-Cohen developed a form a mammography for a diagnostic of breast cancer at earlier stages to improve survival rates.Gardner, Kirsten E. Early Detection: Women, Cancer, and Awareness Campaigns in the Twentieth-Century United States. U of North Carolina P, 2006. p.179 In 1949, Raul Leborgne sparked renewed enthusiasm for mammography by emphasizing the importance of technical proficiency in patient positioning and the adoption of specific radiological parameters. He played a pioneering role in elevating imaging quality while placing particular emphasis on distinguishing between benign and malignant calcifications. In the early 1950s, Uruguayan radiologist Raul Leborgne developed the breast compression technique to produce better quality images, and described the differences between benign and malign microcalcifications.
In 1956, Gershon-Cohen conducted clinical trails on over 1,000 asymptomatic women at the Albert Einstein Medical Center on his screening technique, and the same year, Robert Egan at the University of Texas M.D. Anderson Cancer Center combined a technique of low kVp with high mA and single emulsion films developed by Kodak to devise a method of screening mammography. He published these results in 1959 in a paper, subsequently vulgarized in a 1964 book called Mammography.Medich DC, Martel C. Medical Health Physics. Health Physics Society 2006 Summer School. Medical Physics Publishing. pp.25 The "Egan technique", as it became known, enabled physicians to detect calcification in breast tissue; of the 245 breast cancers that were confirmed by biopsy among 1,000 patients, Egan and his colleagues at M.D. Anderson were able to identify 238 cases by using his method, 19 of which were in patients whose physical examinations had revealed no breast pathology.
Use of mammography as a screening technique spread clinically after a 1966 study demonstrating the impact of mammograms on mortality and treatment led by Philip Strax. This study, based in New York, was the first large-scale randomized controlled trial of mammography screening.
In 1985, László Tabár and colleagues documented findings from mammographic screening involving 134,867 women aged 40 to 79. Using a single mediolateral oblique image, they reported a 31% reduction in mortality. Dr. Tabár has since written many publications promoting mammography in the areas of epidemiology, screening, early diagnosis, and clinical-radiological-pathological correlation.
Keen and Keen indicated that repeated mammography starting at age fifty saves about 1.8 lives over 15 years for every 1,000 women screened. This result has to be weighed against the adverse effects of errors in diagnosis, overtreatment, and radiation exposure.
The Cochrane analysis of screening indicates that it is "not clear whether screening does more good than harm". According to their analysis, 1 in 2,000 women will have her life prolonged by 10 years of screening, while 10 healthy women will undergo unnecessary breast cancer treatment. Additionally, 200 women will experience significant psychological stress due to false positive results.
The Cochrane Collaboration (2013) concluded after ten years that trials with adequate randomization did not find an effect of mammography screening on total cancer mortality, including breast cancer. The authors of this Cochrane review write: "If we assume that screening reduces breast cancer mortality by 15% and that overdiagnosis and over-treatment is at 30%, it means that for every 2,000 women invited for screening throughout 10 years, one will avoid dying of breast cancer and 10 healthy women, who would not have been diagnosed if there had not been screening, will be treated unnecessarily. Furthermore, more than 200 women will experience important psychological distress including anxiety and uncertainty for years because of false positive findings." The authors conclude that the time has come to re-assess whether universal mammography screening should be recommended for any age group. They state that universal screening may not be reasonable. The Nordic Cochrane Collection updated research in 2012 and stated that advances in diagnosis and treatment make mammography screening less effective today, rendering it "no longer effective". They conclude that "it therefore no longer seems reasonable to attend" for breast cancer screening at any age, and warn of misleading information on the internet.
Newman posits that screening mammography does not reduce death overall, but causes significant harm by inflicting cancer scare and unnecessary surgical interventions. (2025). 9781416551539, Scibner. ISBN 9781416551539 The Nordic Cochrane Collection notes that advances in diagnosis and treatment of breast cancer may make breast cancer screening no longer effective in decreasing death from breast cancer, and therefore no longer recommend routine screening for healthy women as the risks might outweigh the benefits.
Of every 1,000 U.S. women who are screened, about 7% will be called back for a diagnostic session (although some studies estimate the number to be closer to 10% to 15%). About 10% of those who are called back will be referred for a biopsy. Of the 10% referred for biopsy, about 3.5% will have cancer and 6.5% will not. Of the 3.5% who have cancer, about 2 will have an early stage cancer that will be cured after treatment.
Mammography may also produce false negatives. Estimates of the numbers of cancers missed by mammography are usually around 20%. Reasons for not seeing the cancer include observer error, but more frequently it is because the cancer is hidden by other dense tissue in the breast, and even after retrospective review of the mammogram the cancer cannot be seen. Furthermore, one form of breast cancer, lobular cancer, has a growth pattern that produces shadows on the mammogram that are indistinguishable from normal breast tissue.
The Canadian Task Force found that for women ages 50 to 69, screening 720 women once every 2 to 3 years for 11 years would prevent one death from breast cancer. For women ages 40 to 49, 2,100 women would need to be screened at the same frequency and period to prevent a single death from breast cancer.
Women whose breast cancer was detected by screening mammography before the appearance of a lump or other symptoms commonly assume that the mammogram "saved their lives".
Lay summary: In practice, the vast majority of these women received no practical benefit from the mammogram. There are four categories of cancers found by mammography:
Only 3% to 13% of breast cancers detected by screening mammography will fall into this last category. Clinical trial data suggests that 1 woman per 1,000 healthy women screened over 10 years falls into this category. Screening mammography produces no benefit to any of the remaining 87% to 97% of women. The probability of a woman falling into any of the above four categories varies with age. (2025). 9781450300308 ISBN 9781450300308
A 2016 review for the United States Preventive Services Task Force found that mammography was associated with an 8%-33% decrease in breast cancer mortality in different age groups, but that this decrease was not statistically significant at the age groups of 39–49 and 70–74. The same review found that mammography significantly decreased the risk of advanced cancer among women aged 50 and older by 38%, but among those aged 39 to 49 the risk reduction was a non-significant 2%. The USPSTF made their review based on data from randomized controlled trials (RCT) studying breast cancer in women between the ages of 40–49.
Research shows that false-positive mammograms may affect women's well-being and behavior. Some women who receive false-positive results may be more likely to return for routine screening or perform breast self-examinations more frequently. However, some women who receive false-positive results become anxious, worried, and distressed about the possibility of having breast cancer, feelings that can last for many years.
False positives also mean greater expense, both for the individual and for the screening program. Since follow-up screening is typically much more expensive than initial screening, more false positives (that must receive follow-up) means that fewer women may be screened for a given amount of money. Thus as sensitivity increases, a screening program will cost more or be confined to screening a smaller number of women.
The importance of these missed cancers is not clear, particularly if the woman is getting yearly mammograms. Research on a closely related situation has shown that small cancers that are not acted upon immediately, but are observed over periods of several years, will have good outcomes. A group of 3,184 women had mammograms that were formally classified as "probably benign". This classification is for patients who are not clearly normal but have some area of minor concern. This results not in the patient being biopsied, but rather in having early follow up mammography every six months for three years to determine whether there has been any change in status. Of these 3,184 women, 17 (0.5%) did have cancers. Most importantly, when the diagnosis was finally made, they were all still stage 0 or 1, the earliest stages. Five years after treatment, none of these 17 women had evidence of re-occurrence. Thus, small early cancers, even though not acted on immediately, were still reliably curable.
According to National Vital Statistics System, mortality from breast cancer has been steadily decreasing in the United States from 2018 to 2021. There have also been no new randomized trials of screening mammography for women in their 40s since the previous USPSTF recommendation was made. In addition, the 8 most recent randomized trials for this age group revealed no significant effect. Instead, the USPSTF used statistical models to estimate what would happen if the starting age were lowered, assuming that screening mammography reduces breast cancer mortality by 25%. This found that screening 1,000 women from 40–74 years of age, instead of 50-74, would cause 1-2 fewer breast cancer deaths per 1,000 women screened over a lifetime.
Approximately 75 percent of women diagnosed with breast cancer have no family history of breast cancer or other factors that put them at high risk for developing the disease (so screening only high-risk women misses majority of cancers). An analysis by Hendrick and Helvie, published in the American Journal of Roentgenology, showed that if USPSTF breast cancer screening guidelines were followed, approximately 6,500 additional women each year in the U.S. would die from breast cancer.
The largest (Hellquist et al) and longest running (Tabar et al) breast cancer screening studies in history re-confirmed that regular mammography screening cut breast cancer deaths by roughly a third in all women ages 40 and over (including women ages 40–49). This renders the USPSTF calculations off by half. They used a 15% mortality reduction to calculate how many women needed to be invited to be screened to save a life. With the now re-confirmed 29% (or up) figure, the number to be screened using the USPSTF formula is half of their estimate and well within what they considered acceptable by their formula.
People with Mental disorder are also less likely to attend cancer screening appointments. In Northern Ireland women with mental health problems were shown to be less likely to attend screening for breast cancer, than women without. The lower attendance numbers remained the same even when marital status and social deprivation were taken into account.
At this time, MQSA applies only to traditional mammography and not to related scans, such as breast ultrasound, stereotactic breast biopsy, or breast MRI.
As of September 10, 2024, the MQSA requires that all patients be notified of their breast density ("dense" or "not dense") in their mammogram reports.
Another study of 32 published papers involving 23,804 mammograms and various machine learning methods (CNN, ANN, and SVM) found promising results in the ability to assist clinicians in large-scale population-based breast cancer screening programs.
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