| Theme |
Depressed type of lesions over 10 mm in size |
| Title |
Molecular pathological features of flat type tumors of colorectum |
| Author |
Hiroshige Hori |
Department of Surgical and Molecular Pathology, Dokkyo University School of Medicine / Field of Translational Medicine, Department of Clinical Molecular Medicine, Division of Gastrointestinal Surgery, Kobe University Graduate School of Medicine |
| Author |
Jun Takeda |
Department of Surgical and Molecular Pathology, Dokkyo University School of Medicine |
| Author |
Shigehiko Fujii |
Department of Surgical and Molecular Pathology, Dokkyo University School of Medicine |
| Author |
Yoshikazu Kuroda |
Field of Translational Medicine, Department of Clinical Molecular Medicine, Division of Gastrointestinal Surgery, Kobe University Graduate School of Medicine |
| Author |
Takahiro Fujimori |
Department of Surgical and Molecular Pathology, Dokkyo University School of Medicine |
| [ Summary ] |
Advances in endoscopic instruments and techniques have increased the rates of detection of early colorectal carcinomas revealed flat type tumors. In Japan, these flat type tumors are usually morphologically diagnosed as the superficial type including depressed type (IIc), elevated type (IIa), etc., using the Japanese Classification of Colorectal Carcinoma. However, Lateral Spreading Tumors (LSTs), a new disease entity, are often observed. LSTs have the morphological feature of horizontal growth and they are classified on the basis of the features of tumor surfaces into two subtypes, the LST-G (Granular) and the LST-NG (Non-Granular). The differences between superficial type tumors and LSTs have been described from various viewpoints. However, descriptions of the molecular biological differences between superficial type tumors and LSTs are not up-to-date. The differences were explained that K-ras mutations were seen frequently in colorectal protruded type tumors, and that p53 gene abnormalities were seen frequently at the time when adenomas developed into adenocarcinomas. The current reports state that LST-NGs and LST-Gs had different formations of K-ras gene, as K-ras mutations were more frequently seen in LST-Gs as well as protruded type tumors and were not in LST-NGs as well as superficial type tumors.
In the present study, the frequency of K-ras codon 12 mutations and the expression of p53 proteins were examined in the viewpoint of tumor morphology and size, using the resected human colorectal tumors. The examination of K-ras codon 12 mutations showed no significant relation to tumor size, but showed a low rate in superficial type tumors and LST-NGs, and a high rate in protruded type tumors and LST-Gs. We also showed that the expression of p53 proteins tended to accumulate in cases of intra mucosal carcinomas and submucosal invasive carcinomas rather than in cases of adenomas. |