What are the screening and prevention recommendations for individuals with category C breast density?

Screening and Prevention Recommendations for Category C Breast Density

For individuals with heterogeneously dense breasts (category C), digital breast tomosynthesis (DBT) should be the primary screening modality, with supplemental screening using ultrasound or MRI recommended based on additional risk factors. 1, 2

Understanding Category C Breast Density

Category C breast density, classified as "heterogeneously dense" in the BI-RADS system, affects approximately 43% of women aged 40-74 years 2. This density classification:

• Reduces mammography sensitivity to approximately 63-75% (compared to 87% in fatty breasts) 2
• Increases breast cancer risk by 23-30% compared to women with average breast density 1, 2
• Creates a "masking effect" that can hide cancers on standard mammography 1

Primary Screening Recommendations

For Average-Risk Women with Category C Breast Density:

• Annual screening beginning at age 40 1
• Digital Breast Tomosynthesis (DBT) as the preferred primary screening modality 1
  • DBT significantly improves cancer detection rates (CDR) in dense breasts 1
  • Reduces recall rates by 18-46% compared to standard mammography 1
  • Detects 1.2-3.0 additional cancers per 1,000 screenings 1

For Intermediate-Risk Women with Category C Breast Density:

(Personal history of breast cancer, history of atypia, LCIS)

• Annual screening with DBT 1
• Supplemental screening with MRI is recommended, especially for:
  • Women with dense breasts AND personal history of breast cancer 1
  • Women diagnosed with breast cancer before age 50 1, 3
  • Women with atypical ductal hyperplasia, atypical lobular hyperplasia, or LCIS 1

For High-Risk Women with Category C Breast Density:

(>20% lifetime risk, genetic mutations, chest radiation at young age)

• Annual screening with DBT 1
• Annual MRI screening starting at ages 25-30 1, 3
• Annual mammography with variable starting age (25-40) depending on risk type 3

Supplemental Screening Options

When primary screening with DBT is completed, supplemental screening should be considered based on risk factors:

1. Breast MRI or Abbreviated Breast MRI (AB-MRI):

   • Preferred supplemental screening for women with dense breasts 1, 3
   • Highest sensitivity for detecting additional cancers (14.7 per 1,000) 4
   • Recommended for women with dense breasts who desire supplemental screening 3

2. Whole Breast Ultrasound:

   • Alternative when MRI is contraindicated or unavailable 1, 3
   • Detects approximately 3.7 additional cancers per 1,000 screens 4
   • Lower specificity than mammography alone (84% vs 91%) 4

3. Contrast-Enhanced Mammography (CEM):

   • Emerging alternative when MRI cannot be performed 3

Implementation Considerations

• Risk Assessment: All women should undergo risk assessment by age 25 to identify those needing earlier or more intensive screening 3

• FDA Notification Requirements: As of September 2024, facilities must notify patients of their breast density status and inform them that supplemental imaging may be beneficial 2

• Potential Harms: Be aware that supplemental screening increases false positive results and unnecessary biopsies 1, 4

Clinical Pitfalls to Avoid

• Overreliance on standard mammography alone in women with dense breasts, as sensitivity is significantly reduced 2

• Failure to consider overall breast cancer risk beyond just breast density when making screening recommendations 2, 3

• Inconsistent supplemental screening practices: Despite widespread availability of supplemental screening modalities, utilization varies significantly between urban and rural facilities 5

• Assuming breast density is static: Breast density can change over time and tends to decrease with age 2