mammography

Indications

• screening & diagnosis of breast disease
  • screening for breast cancer

Benefit/risk

• of no benefit for prevention of breast cancer mortality
• number need to harm
  • 2 within 10 years for false positive
  • 5 within 10 years for unnecessary surgery
• U.S. women are more likely to be aware of screening's benefits than its harms
• AI-supported mammography screening results in a similar rate of cancer detection reading by 2 radiologist, with a substantially lower radiologist workload

Adverse effects

• may in increase risk of breast cancer in women with BRCA1 or BRCA2 mutation
  • increases risk from 22% to 35% by age 40 if mammogram(s) prior to age 30

Procedure

• imaging studies of the breasts by means of X-rays, ultrasound, & nuclear magnetic resonance
• mammography device with option for patient-assisted compression FDA-approved Sept 2017

Notes

• benefits of screening mammography often exaggerated
• 1/3 of breast cancers may be a result of overdiagnosis
• mortality reduction from breast cancer due to screening is 2.4 per 100,000 or ~1/3 (2.4/7.2) of the 7.2 per 100,000 deaths from breast cancer
• no mortality benefit in annual mammography
• overdiagnosis > 20% in the lesions found
• women with false-positive results on screening mammography are more likely to be subsequently diagnosed with breast cancer than women with true-negative results
• overall breast cancer mortality has declined similarly (40-42%) in women > 40 & women < 40 years of age
  • women < 40 years of age are not frequently screened
• clinical trials have not included women > 74 years of age, thus benefits of screening for breast cancer with mammography in patients >= 75 years of age is unknown
• potentially overdiagnosed breast cancer* accounts for 47% of breast cancers in women 75-84 years & 54% of breast cancers in women >= 85 years

* overdiagnosed breast cancer refers to breast cancer detected by screening that would not have caused clinical disease if screening had not occurred

* false positives

• false positive may delay subsequent mammograms
• false positives decrease likelihood of return for screening
• false-positives with 20-year cumulative incidence of breast cancer of 11.3%, vs 7.3% for controls (RR=1.6)
  • association strongest in women 60-76 years, women with lower breast density, & cases of biopsy with diagnosis of benign nature
  • association strongest for ipsilateral cancers

Recommendations*:

• US Preventive Services Task Force (USPSTF)
  • screening mammography with or without clinical breast examination every 1-2 years for women age 50 & older
  • no consensus on upper age limit to discontinue screening, but USPSTF suggests upper age limit of 75
• American Cancer Society recommends annual screening mammography for all women age 45-54 & biennial screening for women age >=55 until life expectancy is < 10 years
  • women should have the opportunity to begin annual screening mammography at age 40 & continue annual screening indefinitely
• American College of Obstetricians and Gynecologists
  • screening mammography annually for women age 40 & older
• screening older women every 2 years reduces false positives (29% vs 48% for annual screening) without change in characteristics of breast cancer diagnoses
• no upper age limit
• uncertain benefit for women > 75-80 years of age

* most recent randomized trial of screening mammography occurred > 50 years ago

* of 1000 women 50 years of age screened yearly for 10 years, 0.3-3.2 fewer breast cancer deaths, 490-670 false-positives & 3-14 overdiagnoses usually leading to unnecessary treatment

Sensitivity: 87%, Specificity 97%

Sensitivity: 36%*, positive predictive value: 89%

False positives:

• annual screening 10 year window: 61% of women
• biennial screening 10 year window: 42% of women

In this same study (BRCA+ women), sensitivity of MRI = 77%

Mammographic breast density:

• risk factor for breast cancer
• genetically determined
• 4 categories of mammographic density
  • almost entirely fat (< 25%)
  • scattered fibroglandular densities (25-50%)
  • heterogenously dense (51-75%)
  • extremely dense (>75%)
• some states may require informing women whether they have dense breast tissue
  • and if so, that dense tissue may hide tumors on mammograms & increase one's risk for breast cancer
• FDA proposes that information on breast density must be included in the mammography summary letter sent to patients
• radiologists often disagree when assessing breast density on mammograms

3 parameters adversely affecting mammographic screening all affect breast density:

• menopausal hormone therapy
  • short-term hormone therapy suspension before mammography not helpful
• prior breast surgery
• body mass index < 25

supplemental ultrasonography to screen women with dense breasts of little benefit

breast density alone shouldn't guide decisions about supplemental screening

incorporating breast cancer risk assessment into mammogram reporting could help determine which women would benefit from supplemental screening

5-year risk for advanced breast cancer more useful than breast density

Digital mammography vs film mammography:

• digital mammography may be better than conventional film mammography when breast tissue is dense
• some cancers may be detected by film only or by digital imaging only.
• women with heterogenously dense or extremely dense breast tissue (BI-RADS categories) should undergo routine digital screening mammography
• computer-aided detection during screening mammography is associated with higher rates of false-positives & subsequent testing, a higher rate of ductal carcinoma in situ diagnosis, & earlier-stage diagnosis of invasive breast cancer
• computer-aided detection does not improve mammography accuracy

3D mammography (tomosynthesis) imaging FDA-approved Feb 2011

• increases cancer detection rates compared with digital mammography alone
• associated with reduced rates of recall for additional imaging

American College of Radiology Breast Imaging Reporting & Data System (BI-RADS) Assessment Categories:

• 0: incomplete assessment; need additional imaging evaluation, prior mammograms for comparison, or both
• 1: negative; normal mammographic study
• 2: benign findings
• 3: probably benign findings; initial short-interval follow-up suggested
• 4: suspicious abnormality; biopsy should be considered
• 5: highly suggestive of malignancy; appropriate action should be taken
• 6: known-biopsy-proven malignancy; appropriate action should be taken

FDA proposes known 'biopsy proven malignancy' available for mammography reports so the it is clear that cancers being mammographically assessed for treatment are already known & identified

FDA can contact patients & providers directly when a facility does not meet reporting requirements

More general terms

• radiography (roentgenography)

More specific terms

• 3D mammography; digital mammography; breast tomosynthesis
• galactography; breast ductography
• mammographic guidance for needle placement
• mammography for biopsy-proven breast cancer

Additional terms

• breast cancer
• screening for breast cancer

Patient information

mammography patient information