| Theme | Revaluation of de nove cancer | |
|---|---|---|
| Title | What is the de novo cancer in the colorectum? Does the de novo cancer exist in the colorectum? | |
| Publish Date | 2009/07 | |
| Author | Takahiro Fujimori | Department of Pathology, Dokkyo Medical University |
| Author | Shigehiko Fujii | Department of Pathology, Dokkyo Medical University |
| Author | Kazuhito Ichikawa | Department of Pathology, Dokkyo Medical University |
| Author | Hideo Ogata | Department of Pathology, Dokkyo Medical University |
| Author | Mio Katano | Department of Pathology, Dokkyo Medical University |
| Author | Yuko Kawase | Department of Pathology, Dokkyo Medical University |
| Author | Hiroyuki Tanaka | Department of Pathology, Dokkyo Medical University |
| Author | Motohiko Hirose | Department of Pathology, Dokkyo Medical University |
| Author | Yukari Fujimori | Department of Pathology, Dokkyo Medical University |
| Author | Hidetsugu Yamagishi | Department of Pathology, Dokkyo Medical University |
| Author | Katsumasa Suzuki | Department of Pathology, Dokkyo Medical University |
| Author | Sho Sekikawa | Department of Pathology, Dokkyo Medical University |
| Author | Hirokazu Fukui | Department of Pathology, Dokkyo Medical University |
| Author | Shigeki Tomita | Department of Pathology, Dokkyo Medical University |
| Author | Joji Imura | Department of Pathology, Dokkyo Medical University |
| Author | Kou Nagasako | Institute of Gastroenterology, Tokyo Women's Medical University |
| [ Summary ] | In studies of the relationship between K-ras mutations and the configuration of colorectal tumors, K-ras mutations have been detected in up to 70% of Ip-type tumors (greatest dimension of polyp head>1cm), whereas these mutations are rare in flat cancer. Therefore, flat colorectal cancers are regarded as candidates for de novo carcinogenesis, deviated from the adenoma-carcinoma sequence, which is widely accepted for the carcinogenesis of the colorectal cancers (ACS, described by Vogelstein, et al.). This is because most colorectal carcinomas appear to have a homogeneous composition that may result from the progression of one of the clones, which has had a K-ras mutation. Additional mutations in the K-ras gene arerarely observed in colorectal carcinomas. On the other hand, alteration of the p53 gene is not only frequently witnessed in the development of carcinoma throughthe ACS, but is also shown to be an early and frequent event in de novo carcinogenesis. The attractive hypothesis for the 'top-down' theory, the 'bottom-up' theory and epithelial-mesenchymal transition (EMT) is relevant for the mechanism of tumorigesis and moving-out (invasion and metastasis). However, to settle these issues, further studies, based on the concepts of niches for cancer stem cells, need to be carried out. | |