Summary about Disease
Familial adenomatous polyposis (FAP) is an inherited disorder characterized by the formation of numerous polyps (abnormal growths) in the colon and rectum. If left untreated, these polyps almost always develop into colorectal cancer. Other associated problems can include polyps in the upper gastrointestinal tract (stomach and small intestine), desmoid tumors (noncancerous growths), osteomas (benign bone tumors), congenital hypertrophy of the retinal pigment epithelium (CHRPE), and certain types of cancer.
Symptoms
Often asymptomatic in early stages
Rectal bleeding
Changes in bowel habits (diarrhea or constipation)
Abdominal pain or cramping
Presence of large numbers of polyps during colonoscopy/sigmoidoscopy.
Anemia (due to chronic blood loss)
Causes
FAP is caused by a mutation in the APC (adenomatous polyposis coli) gene. This gene acts as a tumor suppressor, and its mutation leads to uncontrolled cell growth and polyp formation. The condition is inherited in an autosomal dominant pattern, meaning only one copy of the mutated gene is needed to cause the disorder. About 25-30% of cases are due to a new mutation in the APC gene, meaning there is no family history of the condition.
Medicine Used
NSAIDs (Nonsteroidal Anti-inflammatory Drugs): Sulindac and celecoxib have been used to help reduce the number and size of polyps, but they are not a substitute for surgery.
Chemotherapy: Used if colorectal cancer develops. Chemotherapy medications are selected based on the stage and characteristics of the cancer.
Is Communicable
No, FAP is not communicable. It is a genetic disorder and cannot be spread from person to person.
Precautions
Genetic testing: Individuals with a family history of FAP should undergo genetic testing to determine if they have inherited the mutated APC gene.
Regular screening: Those diagnosed with FAP, or at risk of developing FAP, need regular colonoscopies (usually starting in adolescence) to monitor for polyp growth and detect cancer early.
Prophylactic surgery: Colectomy (removal of the colon) is often recommended as a preventative measure to eliminate the risk of colorectal cancer.
Upper endoscopy: To monitor for polyps in the stomach and duodenum.
How long does an outbreak last?
FAP is not an "outbreak." It is a chronic genetic condition. Polyps will continue to develop throughout a person's life unless the colon is removed.
How is it diagnosed?
Colonoscopy or Sigmoidoscopy: Visualization of numerous polyps in the colon and rectum.
Genetic Testing: Identification of a mutation in the APC gene.
Family History: A known family history of FAP increases the suspicion.
Timeline of Symptoms
Childhood/Adolescence: Usually asymptomatic, but polyps begin to develop.
Teens/Early 20s: Polyps become numerous and may cause rectal bleeding or changes in bowel habits.
30s-40s: If untreated, colorectal cancer is highly likely to develop.
The exact timeline can vary, and regular screening can detect polyps before symptoms appear.
Important Considerations
Prophylactic Colectomy: Is strongly recommended to prevent colorectal cancer. Options include total proctocolectomy with ileostomy or ileal pouch-anal anastomosis (IPAA). The choice depends on the severity of the polyposis and patient preferences.
Lifelong Surveillance: Even after colectomy, surveillance is necessary to monitor the remaining rectum (if not removed) and upper gastrointestinal tract.
Desmoid Tumors: These benign but locally aggressive tumors can occur in FAP patients, sometimes after surgery. They can cause significant morbidity.
Genetic Counseling: Is essential for families with FAP to understand the inheritance pattern, risks, and options for testing and management.
Attenuated FAP (AFAP): A less severe form of FAP with fewer polyps and a later onset of colorectal cancer. It can be more difficult to diagnose.