Hereditary nonpolyposis colon cancer

Hereditary Nonpolyposis Colon Cancer
Synonyms	N/A
Pronounce	N/A
Specialty	N/A
Symptoms	Increased risk of colorectal cancer, endometrial cancer, and other cancers
Complications	N/A
Onset	Typically in adulthood
Duration	Lifelong
Types	N/A
Causes	Genetic mutation in DNA mismatch repair genes
Risks	Family history of HNPCC
Diagnosis	Genetic testing, colonoscopy
Differential diagnosis	N/A
Prevention	N/A
Treatment	Surveillance, surgery, chemotherapy
Medication	N/A
Prognosis	Variable, depending on cancer stage and treatment
Frequency	1 in 370 individuals
Deaths	N/A

Hereditary Nonpolyposis Colon Cancer (HNPCC), also known as Lynch syndrome, is an autosomal dominant genetic condition that significantly increases the risk of developing colorectal cancer and other types of cancer. It is the most common form of hereditary colorectal cancer.

Genetics

HNPCC is caused by germline mutations in one of several DNA mismatch repair (MMR) genes, including MLH1, MSH2, MSH6, PMS2, and EPCAM. These genes are responsible for correcting errors that occur during DNA replication. When these genes are mutated, errors accumulate, leading to increased genomic instability and cancer development.

Inheritance Pattern

HNPCC follows an autosomal dominant inheritance pattern, meaning that an individual only needs to inherit one copy of the mutated gene from an affected parent to be at risk. Each child of an affected individual has a 50% chance of inheriting the mutation.

Clinical Features

Individuals with HNPCC have a significantly increased risk of developing colorectal cancer, often at a younger age than the general population. The average age of onset is around 45 years. In addition to colorectal cancer, individuals with HNPCC are at increased risk for other cancers, including:

• Endometrial cancer
• Ovarian cancer
• Gastric cancer
• Small bowel cancer
• Urothelial cancer
• Biliary tract cancer

Diagnosis

Diagnosis of HNPCC is based on a combination of clinical criteria, family history, and genetic testing.

Clinical Criteria

The Amsterdam Criteria and Bethesda Guidelines are used to identify individuals who should undergo genetic testing for HNPCC. These criteria consider factors such as the number of relatives with colorectal cancer, the age of onset, and the presence of other HNPCC-associated cancers.

Genetic Testing

Genetic testing involves analyzing the MMR genes for mutations. If a mutation is identified, other family members can be tested to determine their risk.

Management

Management of HNPCC involves regular surveillance and preventive measures to reduce cancer risk.

Surveillance

Individuals with HNPCC should undergo regular colonoscopy starting at age 20-25, or 2-5 years earlier than the youngest case in the family. Surveillance for other cancers, such as endometrial and ovarian cancer, may also be recommended.

Surgical Options

Prophylactic surgery, such as colectomy, may be considered in some cases to reduce the risk of colorectal cancer. For women, prophylactic hysterectomy and oophorectomy may be considered to reduce the risk of gynecological cancers.

Chemotherapy

Chemotherapy may be used to treat cancers that develop in individuals with HNPCC. The choice of chemotherapy depends on the type and stage of cancer.

Prognosis

The prognosis for individuals with HNPCC varies depending on the type and stage of cancer at diagnosis. Early detection through surveillance can improve outcomes.

See Also

• Colorectal cancer
• Genetic counseling
• Cancer prevention

External Links

• National Cancer Institute: Lynch Syndrome
• Genetics Home Reference: Lynch Syndrome