From the Guidelines
The best initial test for a 20-year-old man with a family history of hereditary polyposis (Familial Adenomatous Polyposis, FAP) is colonoscopy or sigmoidoscopy.
Key Points
- The risk of developing colorectal cancer (CRC) before age 20 is very low in FAP patients, but it is essential to start screening early to detect adenomas before they become malignant 1.
- According to the European group, endoscopic surveillance should start from the early teens, and since the patient is already 20 years old, sigmoidoscopy every 2 years or colonoscopy should be considered as the initial test 1.
- If an APC mutation of the particular family has been identified, mutation testing can be used as an initial test, but this is not a substitute for endoscopic surveillance 1.
- The patient should be aware of FAP-related symptoms, such as increasing bowel movements, rectal bleeding, and features of anaemia, and report them to their doctor immediately 1.
- Annual colonoscopy should be carried out once adenomas are detected, until colectomy is planned 1.
- It is crucial to continue lifelong surveillance in mutation carriers to reduce the risk of CRC and CRC-associated mortality 1.
From the Research
Initial Testing for Familial Adenomatous Polyposis (FAP)
The best initial test for a 20-year-old man with a family history of hereditary polyposis (Familial Adenomatous Polyposis, FAP) is:
- Genetic testing for mutations in the APC gene, which is the primary gene responsible for FAP 2, 3
- Predictive testing for first-degree relatives is possible from the age of 10 to 12 years on, but for a 20-year-old, genetic testing can be considered if the family's specific APC mutation is identified 2
- Colonoscopy may also be considered as an initial test, as it can detect adenomatous polyps in the colon and rectum, which are characteristic of FAP 4, 3
Considerations for Testing
- A family history of FAP is an indicator to start early screening in patients, especially those with a paternal family history of the disease 4
- Clinical suspicion for FAP should be kept in mind, especially in young patients without a family history and unexplained heme-positive stool 4
- Other findings that could suggest FAP include a personal or family history of extra-colonic manifestations such as fibromas, osteomas, or dentition abnormalities 4, 5
Genetic Counseling
- Genetic counseling is crucial for helping FAP patients and their relatives understand the syndrome and its implications 6
- Genetic counseling can occur at several time points, including when FAP is diagnosed, when an FAP patient is considering reproductive options, and when an at-risk person is considering genetic testing 6