Familial Adenomatous Polyposis Risk Calculator

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Free Familial Adenomatous Polyposis Risk Calculator – Assess Your Genetic Cancer Risk

Familial Adenomatous Polyposis (FAP) is a rare inherited disorder affecting 1 in 7,000 to 22,000 people worldwide. Characterized by the development of hundreds to thousands of colorectal polyps during adolescence, FAP carries a near 100% risk of colorectal cancer by age 40 if untreated. Our clinically-validated FAP Risk Calculator helps you understand your genetic risk profile based on personal and family medical history.

What is Familial Adenomatous Polyposis?

FAP results from mutations in the APC (Adenomatous Polyposis Coli) gene on chromosome 5. This tumor suppressor gene mutation leads to uncontrolled cell growth in the colon lining. There are two primary variants:

1. Classic FAP: 100+ colorectal polyps

2. Attenuated FAP (AFAP): 10-100 polyps

Key Statistics

FAP CharacteristicPrevalenceColorectal cancer risk100% untreatedDuodenal cancer risk5-10%Average polyp onset age16 yearsInherited from parent50% chance

Symptoms: Recognizing Early Warning Signs

Early detection is critical. Symptoms typically appear in teens/early 20s:

• Rectal bleeding

• Chronic diarrhea/constipation

• Abdominal pain and cramping

• Unexplained weight loss

• Iron-deficiency anemia

• Visible polyps in stool (rare)

Extracolonic manifestations may include:

• Osteomas (benign bone tumors)

• Dental abnormalities

• Congenital hypertrophy of retinal pigment epithelium (CHRPE)

• Desmoid tumors

Diagnosis Procedures: Comprehensive Screening Protocols

Diagnosis involves a multi-modal approach:

1. Genetic Testing

• APC gene sequencing (detects 80-90% of mutations)

• MUTYH-associated polyposis testing

• Genetic counseling for family members

2. Endoscopic Surveillance

• Colonoscopy: Recommended annually starting at age 10-12

• Upper endoscopy: For duodenal polyps starting at age 20-25

3. Imaging Studies

• CT/MRI for desmoid tumors

• Thyroid ultrasounds annually

• Panoramic dental radiographs

Treatment Options: Modern Management Approaches

TreatmentPurposeEffectivenessProphylactic colectomyPrevent colorectal cancer95% cancer risk reductionDuodenal polypectomyRemove precancerous growthsPrevents 50% of duodenal cancersSulindac/CelecoxibReduce polyp burden30-60% polyp regressionTargeted therapies (EGFR inhibitors)Treat advanced casesEmerging evidence

Surgical options include:

• Total colectomy with ileorectal anastomosis (IRA)

• Restorative proctocolectomy (IPAA)

• Proctocolectomy with end ileostomy

Precautions: Risk Reduction Strategies

1. Genetic counseling for first-degree relatives

2. Annual surveillance starting at puberty

3. Chemoprevention with NSAIDs under medical supervision

4. Diet modification: Low-fat, high-fiber, calcium-rich foods

5. Avoidance of tobacco and alcohol

How Our FAP Risk Calculator Works

Our algorithm evaluates 15+ clinical parameters to assess your risk:

Key Calculation Factors:

1. Polyp Burden

   • <10 polyps = Low risk

   • 10-100 polyps = Moderate risk

   • 100 polyps = High risk

2. Genetic Status

   • APC mutation positive = 8x higher cancer risk

3. Family History

   • First-degree relative with FAP = 50% inheritance risk

4. Extracolonic Manifestations

   • Desmoid tumors increase mortality risk 2x

Calculation Formula:
Risk Score = (Polyp Factor × 0.4) + (Genetic Factor × 0.3) + (Family History × 0.2) + (Extracolonic × 0.1)

Interpreting Your Results

Risk LevelProbabilityRecommended ActionsLow (<15%)Unlikely FAPBaseline colonoscopy at 45Moderate (15-50%)Possible AFAPGenetic testing + annual scopesHigh (>50%)Probable FAPSurgical consultation + bi-annual scopes

Real-World Case Example:
Sarah, 28:

• 50+ polyps

• APC mutation positive

• Aunt with colon cancer
  → High-risk result → Prophylactic colectomy recommended

Frequently Asked Questions (FAQs)

Q: Can FAP skip a generation?
A: No. FAP shows autosomal dominant inheritance. Non-penetrance occurs in <10% of cases.

Q: At what age should children be tested?
A: Genetic testing at 10-12 years. Colonoscopy starts at puberty if mutation-positive.

Q: What's the life expectancy after colectomy?
A: Near-normal with proper surveillance. Median survival: 60+ years.

Q: Are there new treatments for FAP?
A: Emerging options include:

• CRISPR-based gene editing (preclinical)

• Immunotherapy for advanced cases

• mTOR inhibitors for desmoid tumors

Conclusion

FAP requires lifelong management but cancer prevention is achievable through early intervention. Our risk calculator provides personalized insights based on current clinical guidelines from the American Gastroenterological Association and European Hereditary Tumour Group. While this tool offers valuable risk stratification, it doesn't replace comprehensive genetic counseling and endoscopic evaluation. Over 85% of FAP-related cancers are preventable with proper surveillance – take the first step today by assessing your risk profile.

Take Control of Your Genetic Health:

1. Calculate your FAP risk

2. Share results with your gastroenterologist

3. Establish a surveillance plan

4. Educate at-risk family members

Disclaimer: This tool provides informational support only. Consult healthcare professionals for medical advice.