Hereditary nonpolyposis colorectal cancer

Hereditary nonpolyposis colorectal cancer (HNPCC), also known as Lynch syndrome, is a type of inherited cancer of the digestive tract, particularly the colon and rectum. It is characterized by the development of cancer at a relatively young age and the occurrence of other types of cancer, including endometrial, ovarian, gastric, urinary tract, brain, and skin cancers.

Etiology

HNPCC is caused by mutations in genes that help repair errors in DNA. These genes, known as Mismatch Repair (MMR) genes, include MLH1, MSH2, MSH6, PMS2, and EPCAM. When these genes are functioning normally, they help correct mistakes that occur when DNA is copied in preparation for cell division. Mutations in any of these genes prevent the repair of DNA replication errors, which can accumulate and lead to cancer.

Clinical Presentation

Individuals with HNPCC typically develop colorectal cancer before the age of 50. The cancer often develops in the right side of the colon, which is different from sporadic cases of colorectal cancer. Other symptoms may include changes in bowel habits, abdominal pain, and unexplained weight loss.

Diagnosis

Diagnosis of HNPCC involves a combination of clinical criteria, known as the Amsterdam criteria and the Revised Bethesda guidelines, and genetic testing. Genetic testing can identify mutations in the MMR genes, confirming the diagnosis.

Treatment

Treatment for HNPCC involves surgery to remove the cancer, often followed by chemotherapy. Regular screening for colorectal cancer and other associated cancers is recommended for individuals with HNPCC and their at-risk relatives.

Prognosis

The prognosis for individuals with HNPCC varies depending on the stage of the cancer at diagnosis. Early detection and treatment can significantly improve survival rates.

See Also

• Colorectal cancer
• Genetic testing
• Cancer genetics

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