Screening and Prevention of Extracolonic Cancers in Patients with Hereditary Nonpolyposis Colon Cancer

Hereditary nonpolyposis colon cancer is the most common cause of hereditary colon cancer and results from defects in mismatch repair genes that create the phenomenon of microsatellite instability. Apart from the high risk of colon cancer, these patients are at increased risk of multiple malignancies, including endometrial cancer, ovarian cancer, small bowel tumors, gastric cancer, pancreatic cancer, and multiple other extraintestinal tumors. Routine colonoscopy for patients with hereditary nonpolyposis colon cancer has become standard and is widely accepted, but screening regimens for other organs remain matters of debate. Inadequacies detected in attempted surveillance methods have led some authors to call for prophylactic surgery as an alternative strategy in cancer prevention.