FAMILIAL GIANT HYPERPLASTIC POLYPOSIS PREDISPOSING TO COLORECTAL-CANCER - A NEW HEREDITARY BOWEL-CANCER SYNDROME

A mother and five of her ten offspring colonic cancers, the mother and one of the offspring being younger than 50 years of age at diagnosis. Despite fulfilling the Amsterdam criteria for hereditary non-polyposi s colorectal cancer (HNPCC), several features pointed towards the poss ibility that this represented a different syndrome of familial cancer. Most notable was the presence of large, multiple hyperplastic polyps and mixed polyps in four of the subjects whose pathology was available for review. In addition, three of the four subjects had cancers that were negative for DNA replication errors (RER-). The subject with an R ER+ cancer had a second RER+ cancer and three adenomas, one in contigu ity with the second cancer. This subject also had multiple, large hype rplastic polyps, thereby combining hyperplastic polyposis and a pronen ess to multiple RER+ tumours. One of the hyperplastic polyps was also RER+. Two of five young asymptomatic descendants have been found to ha rbour multiple colorectal polyps. It is suggested that giant hyperplas tic polyposis is a new familial syndrome predisposing to colorectal ca ncer.