1993 年 46 巻 5 号 p. 475a
Lynch syndrome I is characterized by an autosomal dominant predisposition to colorectal cancer (CRC) with predilection to the proximal colon and an excess of metachronous CRC. The Lynch syndrome II variant shows these same features but, in addition, shows significant excess of carcinomas of the endometrium, ovary, ureter, renal pelvis, small bowel, and stomach. There are no premonitory physical signs of cancer risk. The gene has been recently mapped to chromosome 2p15-16 (Science 260:810-812, 1993) and, once cloned, will significantly abet the detection of gene carriers through a simple blood test. The disorder is common and may account for between 6-10% of the total CRC burden. Surveillance must be responsive to its natural history. In both variants, we recommend colonoscopy to be initiated at age 25 and repeated every other year, and in Lynch syndrome II, surveillance for extracolonic cancer. Because of the excess of metachronous cancer, subtotal colectomy is necessary for initial CRC.