In view of the changing concepts of @entity14 during the past 20 years, a historical review of @entity14 is presented. The concept of @entity14 is presented in four different periods: 1) @entity105 based on surgical materials; 2) @entity105 based on polypectomy materials; 3) @entity105 based on nonpolypoid neomaterials; and 4) @entity105 based on molecular biology. In the first period, large @entity652 were thought to play the most important role as precursors of @entity14 . The concept was referred to as the " @entity2513 sequence." However, in the second period, smaller and nonpedunculated @entity652 were found to have a much higher malignancy potential than previously thought. The natural history of @entity14 revealed morphological changes from polypoid or sessile lesions to ulcerating @entity189 during a varying time span. The @entity5 , including flat and @entity308 @entity652 / @entity189 , shed light on new precursors of @entity14 that had not been recognized in the past. They tend to have a much higher malignant @entity5 . Molecular biology clarified the absence of @entity984 mutation in nonpolypoid, particularly @entity308 , @entity5 , suggesting the presence of a novel pathway of @entity14 different from that in polypoid @entity5 . The concept referred to as the " @entity2513 sequence" changed because colonoscopic polypectomy specimens were studied, and rather small nonpeduculated @entity652 were found to play an important role as precursors of @entity14 . The discovery of nonpolyoid @entity5 provided us with new precursors of @entity14 . The genetic alterations in nonpolypoid @entity5 seem to differ from those in polypoid @entity5 . Carcinogenesis of so-called de novo @entity189 should be explained on a molecular basis. When sequential multistep genetic alterations take place very rapidly the @entity189 seems to arise de novo. Until the gene responsible for real de novo @entity189 is detected, the term de novo-type @entity189 should be used.

[Colorectal XXXX : a historical review].

@entity308 :: ('MESH:D003866', 'Disease') :: ['depressed'] @entity5 :: ('MESH:D009369', 'Disease') :: ['potential than polypoid neoplasms', 'discovery of nonpolypoid neoplasms', 'neoplasms'] @entity984 :: ('3845', 'Gene') :: ['K-ras'] @entity189 :: ('MESH:D002277', 'Disease') :: ['carcinomas', 'carcinoma'] @entity14 :: ('MESH:D015179', 'Disease') :: ['colorectal carcinogenesis', 'colorectal neoplasms', 'colorectal carcinomas'] @entity652 :: ('MESH:D000236', 'Disease') :: ['adenomas'] @entity105 :: ('MESH:D063646', 'Disease') :: ['carcinogenesis'] @entity2513 :: ('MESH:C563365', 'Disease') :: ['adenoma-carcinoma']
@entity105 :: (MESH:D063646,Disease) :: ['carcinogenesis']
