UPDATE ON THE DIFFERENTIAL-DIAGNOSIS, SURVEILLANCE AND MANAGEMENT OF HEREDITARY NONPOLYPOSIS COLORECTAL-CANCER

Hereditary non-polyposis colorectal cancer (HNPCC) is the most common hereditary form of colorectal cancer (CRC), accounting for approximate ly 10% of the total CRC burden. HNPCC lacks premonitory physical stigm ata, thereby making the family history crucial for diagnosis. Advances in molecular genetics during the past 2 years have led to the cloning of four HNPCC genes (MHS2, MLH1, PMS1 and PMS2). It is now possible t o provide presymptomatic DNA testing followed by genetic counselling f or gene carriers. Some studies have shown that adenomas in HNPCC are l arger, more villous, and have more high grade dysplasia than sporadic cases, suggesting an accelerated adenoma-carcinoma sequence. Given the early age of onset and proximal predominance of CRC, we initiate colo noscopy at age 20-25 years and we recommend that it be performed every 1-2 years. The wealth of clinical and molecular genetic knowledge cur rently available to physicians about HNPCC can be used effectively for cancer control.