Which is more sensitive for breast cancer screening, X-ray (X-ray) mammography or sono (ultrasound) mammogram?

Comparison of X-ray Mammography vs. Ultrasound Mammography for Breast Cancer Screening

X-ray mammography is more sensitive than ultrasound mammography for breast cancer screening in the general population, with sensitivity ranging from 60-90% compared to ultrasound's sensitivity of 67.2%. 1

Sensitivity Comparison by Imaging Modality

• X-ray mammography has a sensitivity between 60-90% for detecting breast cancer in the general screening population 1
• Ultrasound mammography has an overall sensitivity of approximately 67.2% (range 26.9%-87.5%) 2
• MRI has the highest sensitivity at 94.6% (range 85.7%-100%) but is not recommended for routine screening due to high cost and false-positive rates 1, 2

Factors Affecting Sensitivity

Breast Density

• X-ray mammography is significantly less sensitive in women with dense breast tissue 1
• Ultrasound may be more valuable as an adjunct tool in women with dense breasts 1, 3
• Digital mammography shows higher accuracy than film mammography in women with heterogeneously dense or extremely dense breasts 4

Age

• Mammography is less sensitive and results in less mortality reduction in younger women 1
• This decreased benefit may be due to greater mammographic density and more rapid tumor growth in younger women 1
• Ultrasound has been considered as a screening tool for younger women at high risk, though evidence doesn't support its use as a standalone screening method 1

Specific Detection Capabilities

• X-ray mammography is superior at detecting microcalcifications, which are often associated with early-stage cancers and DCIS 1, 3
• Ultrasound is better at detecting masses, especially in dense breast tissue 1, 3
• Combined use of mammography and ultrasound increases sensitivity compared to either modality alone 2, 5

Expert Recommendations

• The European Group for Breast Cancer Screening concluded there is no evidence to support the use of ultrasound for screening at any age 1
• Ultrasound has a well-established role in the diagnostic work-up of palpable breast lesions and for correlating findings with mammography or MRI 1
• The combination of mammography and ultrasound shows better sensitivity than either modality alone, with studies showing sensitivity increasing to 93.3% when both are used 5

Clinical Applications

• Mammography remains the primary screening tool for breast cancer detection in the general population 1
• Ultrasound is most valuable as an adjunct to mammography, particularly for:
  • Evaluating palpable abnormalities 1
  • Assessing women with dense breast tissue 3, 5
  • Further characterizing findings detected on mammography 1

Common Pitfalls and Caveats

• Ultrasound is highly operator-dependent, requiring skilled technologists and radiologists 1
• Ultrasound has a higher false-positive rate compared to mammography in some studies 1
• The sensitivity of both modalities is affected by breast density, with mammography particularly limited in dense breasts 1, 4
• Neither modality alone is sufficient for high-risk women, for whom MRI is recommended as an adjunct to mammography 1