Adenomatosis polyposis coli

Adenomatous Polyposis Coli (APC) is a genetic disorder characterized by the development of hundreds to thousands of benign tumors called adenomas in the colon and rectum. Individuals with this condition have a significantly increased risk of developing colorectal cancer at a young age. APC is primarily associated with two inherited conditions: Familial Adenomatous Polyposis (FAP) and its variant, Attenuated Familial Adenomatous Polyposis (AFAP). The disorder is caused by mutations in the APC gene, which plays a crucial role in controlling cell growth and cell death, acting as a tumor suppressor.

Genetics

The APC gene is located on chromosome 5 (5q21-q22) and is responsible for producing a protein that helps control the rate at which cells divide. Mutation of the APC gene leads to the development of polyps by allowing uncontrolled cell division, primarily in the tissues of the colon and rectum. These mutations are usually inherited in an autosomal dominant pattern, meaning only one copy of the altered gene is sufficient to increase the risk of developing polyps and cancer. However, a person inheriting the defective gene has a 100% chance of developing FAP, making early diagnosis and management crucial.

Clinical Presentation

Individuals with APC typically begin to develop polyps in their teens or early adulthood, although the polyps can start to appear in childhood. Without preventive surgery, nearly all individuals with classical FAP will develop colorectal cancer by the age of 40. Symptoms may include blood in the stool, abdominal pain, and changes in bowel habits, although many individuals may be asymptomatic in the early stages of the disease.

Diagnosis

Diagnosis of APC is based on a combination of clinical findings, family history, and genetic testing. Colonoscopy is the primary diagnostic tool, allowing for the visualization and biopsy of polyps. Genetic testing can identify mutations in the APC gene, confirming the diagnosis and allowing for family screening.

Management

Management of APC involves regular surveillance with colonoscopy to monitor for the development of polyps and cancer. Prophylactic colectomy, the surgical removal of the colon, is often recommended to prevent colorectal cancer. The timing of surgery depends on the number, size, and histology of the polyps, as well as patient and family preferences. After surgery, patients may require regular follow-up and management of any remaining rectal stump, if not removed, or ileal pouch to monitor for polyp development.

Prognosis

The prognosis for individuals with APC greatly improves with early detection and management of polyps and cancer. Prophylactic surgery to remove the colon significantly reduces the risk of colorectal cancer. However, individuals with APC may still have an increased risk of developing other cancers, including cancers of the thyroid, liver, and pancreas, necessitating ongoing surveillance.