De Benedetti et al (1994) reported that frameshift mutation of APC gene was predominant in polypoid adenomas, with APC mutations participating in progression of exophytic adenomas. In contrast, Umetani et al (2000) have reported that the frequency of APC mutation in nonpolypoid adenomas was significantly lower than that in polypoid adenomas, while being similar between polypoid carcinomas and nonpolypoid carcinomas. The gene discussed is APC; the disease is adenoma.