The rate of onset and progression of colorectal cancer is one of the most pressing issues in oncology. Until recently, the concept of the predominant pathway of carcinogenesis in the colon was limited to the well-known concept of B.C. Morson (1968-1975) “ACSequence”, which suggests a gradual, over many years, malignant transformation of adenomatous polyps as the degree of epithelial dysplasia increases. However, in one of his works, B.C. Morson advanced the insightful idea of the fundamental possibility of cancer developing “de novo,” i.e., bypassing the stage of a large adenoma.
The incidence of adenomatous polyps detected in patients exceeds the incidence of colon cancer by approximately 5,000-10,000 times (!). This striking discrepancy must be taken into account when planning screening and cancer prevention measures, which, unfortunately, have not yet achieved the desired results. Can an advanced cancerous tumor develop from a pre-existing adenoma within 3-6 months, bypassing the stage of a large adenomatous polyp, rather than within 5-10 years? What morphological changes in the colonic mucosa precede the development of rapidly growing cancer? Are all cases of interval cancer explained solely by diagnostic error on the part of the endoscopist?
The pathoembryonic theory of the development of rapidly growing cancers, the foundations of which are outlined in the article «Colorectal and Stomach Cancer, a New Look at the Features of Morphogenesis», provides a sound answer to the above questions. According to the authors, rapidly growing cancerous tumors arise from somatic hybridization—the fusion of hyperplastic epithelial cells with adjacent small adenoma’s cells. The specific mechanism for the rapid malignancy of hybrid cells remains to be elucidated.