How can breast cancer risk calculators be used to assess and manage breast cancer risk?

Breast Cancer Risk Calculators for Assessment and Management

Breast cancer risk calculators should be used to identify women at elevated risk, guide appropriate screening protocols, and determine eligibility for risk reduction strategies including chemoprevention and enhanced surveillance. 1

Types of Risk Assessment Models

Several validated risk assessment models are available, each with specific strengths and applications:

Modified Gail Model (BCRAT)

• Available through NCI website (http://www.cancer.gov/bcrisktool/Default.aspx)
• Appropriate for women ≥35 years of age
• Considers: age, ethnicity, history of breast biopsy and breast cancer, age at menarche, parity, and age at first live birth
• Threshold of ≥1.7% 5-year risk is used to identify candidates for chemoprevention 1, 2
• Limitations: Does not adequately analyze detailed family histories; underestimates risk in BRCA1/2 carriers and women with strong family history 1

Family History-Based Models

• Tyrer-Cuzick (IBIS): Incorporates family history and epidemiologic variables
• BRCAPRO: Estimates both breast cancer risk and likelihood of BRCA mutation
• Claus Model: Useful for women with affected first- and second-degree relatives
• BOADICEA: Analyzes family history in first-degree and second-degree relatives on both maternal and paternal sides 1

Risk Stratification and Management Algorithm

Step 1: Determine Appropriate Risk Calculator

• For average-risk assessment: Modified Gail Model for women ≥35 years
• For women with strong family history: Use Tyrer-Cuzick, BRCAPRO, Claus, or BOADICEA models 1
• Not appropriate for Gail Model: Women with known genetic mutations, prior thoracic radiation before age 30, or history of LCIS 1

Step 2: Risk Assessment and Classification

• Average risk: <1.7% 5-year risk by Gail model
• Intermediate risk: ≥1.7% 5-year risk by Gail model
• High risk: ≥20-25% lifetime risk by specialized models, known BRCA mutation carriers, or history of thoracic radiation before age 30 1

Step 3: Management Based on Risk Level

For Average-Risk Women:

• Standard screening mammography according to age-appropriate guidelines
• Regular clinical breast exams

For Intermediate-Risk Women (≥1.7% 5-year risk):

• Standard screening mammography
• Consider chemoprevention with tamoxifen (premenopausal) or raloxifene/aromatase inhibitors (postmenopausal) 1, 2, 3
• Clinical breast exams every 6-12 months 4

For High-Risk Women (≥20-25% lifetime risk):

• Annual mammography starting at age 30 (or 10 years before earliest breast cancer in family)
• Annual breast MRI screening in addition to mammography 1
• Consider risk-reduction strategies including chemoprevention or prophylactic surgery 1
• More frequent clinical breast exams (every 6-12 months) 4

Clinical Implementation Tips

1. Use multiple models when appropriate: Different models may identify different women at high risk 1, 5

   • In one study, only 0.2% of women were classified as high-risk by all three models (Tyrer-Cuzick, BRCAPRO, and Gail) 5
   • Tyrer-Cuzick model identified more high-risk women than the Gail model 5

2. Consider genetic counseling referral when:

   • Multiple relatives with breast or ovarian cancer
   • Relatives diagnosed with breast/ovarian cancer under age 50
   • Family history on either maternal or paternal side 1

3. Update risk assessment periodically:

   • When family history changes (e.g., new cancer diagnoses in relatives)
   • For women who choose not to have regular screening 1

Common Pitfalls to Avoid

1. Using inappropriate models: Don't use Gail model for women with known genetic mutations or strong family history 1

2. Overlooking paternal family history: Breast cancer risk can be inherited equally from maternal and paternal sides 1

3. Relying on a single model: Each model has unique strengths and limitations; consider using multiple models for high-risk assessment 1, 5

4. Overestimating accuracy: Models predict risk for groups well but may be less accurate for individual women 6

   • The Gail model has been shown to overpredict absolute risk by 33% in some populations 6
   • However, more recent validation in screening populations shows better calibration 7

5. Neglecting risk reduction counseling: Women identified as high-risk should receive comprehensive counseling about risk reduction options 1

By systematically applying these risk assessment tools and following evidence-based management strategies, clinicians can effectively identify women at elevated breast cancer risk and implement appropriate screening and risk reduction measures to improve outcomes.