[Autoregulatory growth control of adenomatous polyps and carcinogenesis in the colorectal region. Basics of tumor surgery Part I].

Autoregulatory growth control of adenomatous polyps in the colon and rectum is an important factor in the success of sphincter-sparing surgical resections. It is the basis for the coexistence of billions of somatic cells in multicellular organisms. Similar to normal mucosa, adenomatous polyps in the colorectum show autoregulatory growth control in their tissues. This applies whether they are differentiated or undifferentiated. In most cases, their growth and expansion is controlled throughout life. While colorectal adenomas have malignant potential, their transformation to cancerous lesions is exceedingly rare (e.g., in familial polyposis, or FAP, with a prevalence of only one in 10,000). It has been hypothesized that "fully developed adenomas" frequently are a prestage of colorectal cancer. However, convincing evidence on a molecular level that this so-called adenoma-carcinoma sequence indeed occurs in vivo is lacking. In contrast, there is good evidence that colorectal carcinogenesis is a microevolutionary process and that the irrevocable loss of autoregulatory growth control is one of its features. The most prominent homing area for colorectal cancer is the rectum. If the rectum is resected, metachronous cancer occurs only very rarely. The most distal quarter of the rectum is cloacal in origin and a pivotal structure for anorectal continence. It should be preserved whenever a more proximal location of the tumor makes this possible. These conclusions are based on our extensive case series and observations extending over several decades.