What is the management of familial adenomatous polyposis (FAP) with hundreds of polyps on exam?

Management of Familial Adenomatous Polyposis with Hundreds of Polyps

Patients with FAP and hundreds of polyps should undergo prophylactic proctocolectomy with ileoanal pouch anastomosis between ages 16-20 years to prevent colorectal cancer development. 1

Diagnosis and Initial Assessment

When a patient presents with hundreds of colorectal polyps, the diagnosis of classical familial adenomatous polyposis (FAP) should be confirmed through:

• Genetic testing for APC gene mutations (detectable in >70% of typical FAP cases) 1, 2
• Family history assessment (present in ~70% of cases) 3
• Evaluation for extracolonic manifestations:
  • Duodenal adenomas
  • Thyroid nodules
  • Desmoid tumors
  • Osteomas
  • Congenital hypertrophy of retinal pigment epithelium (CHRPE)

Surgical Management

The presence of hundreds of polyps indicates classical FAP, which carries a 100% lifetime risk of colorectal cancer if left untreated 3. Two main surgical options exist:

1. Proctocolectomy with ileoanal pouch anastomosis (IPAA):

   • Preferred option for patients with severe rectal polyposis (hundreds of polyps)
   • Removes entire colon and rectum, eliminating risk of rectal cancer
   • Long-term cancer risk reduction is superior to IRA 1

2. Total colectomy with ileorectal anastomosis (IRA):

   • May be considered in patients with relatively few rectal polyps
   • Preserves rectal function but requires lifelong surveillance
   • Risk of rectal cancer remains (12-29%) 1

For patients with hundreds of polyps, IPAA is strongly recommended due to the high polyp burden and subsequent cancer risk 1, 4.

Timing of Surgery

• Surgery should be performed between ages 16-20 years 1
• Surgery may be delayed briefly for important educational episodes, but patients with large numbers of polyps should be strongly discouraged from delaying surgery 1
• Patients with hundreds of polyps should undergo surgery before age 25 1

Post-Surgical Surveillance

After surgery, ongoing surveillance is essential:

1. For patients with IPAA:

   • Annual endoscopic examination of the ileoanal pouch/anal transition zone for life 1

2. For patients with IRA (if chosen despite high polyp burden):

   • Annual examination of the retained rectum for life 1

3. Upper gastrointestinal surveillance:

   • Begin at age 25 years or when colorectal polyposis is diagnosed (whichever comes first) 1, 2
   • Repeat every 3 years if normal
   • Frequency increases based on Spigelman staging of duodenal polyposis 2

4. Extracolonic manifestation screening:

   • Annual thyroid ultrasound 2, 5
   • Regular physical examination for desmoid tumors 2, 5
   • Abdominal imaging for high-risk patients (family history of desmoids, prior surgery) 2

Chemoprevention

• Adjunctive therapy with celecoxib may be considered for management of remaining adenomas after surgery 3
• This should not replace appropriate surgical management or surveillance

Common Pitfalls to Avoid

1. Delaying surgery: With hundreds of polyps, cancer risk is high and surgery should not be unnecessarily delayed 1

2. Inadequate surveillance: Lifelong monitoring is essential even after surgery 1, 2

3. Focusing only on colorectal manifestations: FAP is a multisystem disorder requiring comprehensive surveillance for extracolonic manifestations 5

4. Choosing IRA for patients with severe rectal polyposis: While IRA may offer better functional outcomes (fewer stools, less incontinence), the cancer risk with hundreds of polyps makes IPAA the safer option 1, 6

Recent evidence suggests that intensive endoscopic surveillance and adenoma destruction may allow for rectal preservation in some patients 6, but with hundreds of polyps, the standard recommendation remains proctocolectomy with IPAA to maximize cancer prevention 1, 4.