Modified complete mesocolic excision with central vascular ligation for the treatment of right-sided colon cancer: long-term outcomes and prognostic factors.

OBJECTIVE: To investigate the long-term oncologic outcomes and risk factors for adverse effects in right-sided colon cancer patients who underwent modified complete mesocolic excision (mCME). BACKGROUND: Complete mesocolic excision (CME) with central vascular ligation has recently been found to improve oncological outcomes in patients with colon cancer. Our institution has established mCME on the basis of the original concept of CME for the treatment of right-sided colon cancer. METHODS: Between January 2000 and July 2009, 773 patients who underwent mCME for right-sided colon cancer were eligible for this retrospective study. The prognostic factors for survival/recurrence and the risk factors for postoperative complications were investigated. RESULTS: The mean follow-up period was 61.9 ± 34.7 months. The 5-year overall survival and 5-year disease-free survival rates were 84.0% and 82.8%, respectively. Pathologic stage III disease, postoperative complications, age more than 60 years, and minimally invasive surgery were found to be independent prognostic factors. The 5-year locoregional recurrence (LRR) and 5-year systemic recurrence rates (SRRs) were 4.9% and 13.7%, respectively. The risk of LRR and SRR increased with pathologic stage III disease. An American Society of Anesthesiology score of higher than II was an independent predictive factor of postoperative complications. CONCLUSIONS: We have successfully established the mCME technique, on the basis of the same principle as CME, but with a more tailored approach. The long-term oncologic outcomes and risk of postoperative morbidity were found to be comparable with those seen with the original CME procedure.

Comparison of the clinicopathologic features between flat and polypoid adenoma.

OBJECTIVE: Several reports have suggested that flat colorectal adenomas might exhibit a higher potential for malignancy compared to polypoid adenomas. Although the clinical importance of the shape of polyps is stressed, the controversy surrounding the malignant potential of flat adenomas continues. The aim of this study was to compare the clinicopathologic characteristics, including degree of dysplasia and malignancy, between flat and polypoid adenomas 5 mm in size or larger. MATERIAL AND METHODS: A total of 3263 polyps (254 flat adenomas and 3009 polypoid adenomas), >/=5 mm in size, diagnosed in 1883 patients by colonoscopy were analyzed. RESULTS: Flat adenomas were found in 10% of patients, which represented 7.8% of all adenomas removed. The flat adenomas were larger in diameter than the polypoid adenomas (14.8+/-12.6 mm versus 8.6+/-5.0 mm, p <0.01), had a higher rate of villous components (18.5% versus 11.4%, p <0.01), a higher rate of high-grade dysplasia (9.4% versus 4.2%, p <0.01), and a higher rate of malignancy (10.2% versus 3.6%, p <0.01) than polypoid adenomas. However, there was no difference in the rate of high-grade dysplasia or carcinoma between flat and polypoid adenomas of equal size. It was shown by multivariate analysis that rectosigmoid location, larger size, and presence of a villous component were associated with a higher rate of malignancy, but not with flat morphology. CONCLUSIONS: Flat adenomas, which were of a relatively large size in this study, were not associated with a higher risk for high-grade dysplasia and carcinoma compared with polypoid adenomas.

Different gene expression profiles between microsatellite instability-high and microsatellite stable colorectal carcinomas.

Recent molecular genetic studies have revealed that two major types of genomic instabilities, chromosomal instability (CIN) and microsatellite instability (MSI), exist in colorectal carcinomas. In order to clarify the molecular signature related to the CIN and MSI in colorectal carcinomas, we performed transcriptomic expression analysis on eight microsatellite instability-high (MSI-H) colorectal carcinomas and compared the results obtained with that of nine microsatellite stable (MSS) colorectal carcinomas using oligonucleotide microarrays containing 17 334 known genes and 1331 unknown genes or expression sequence tags (ESTs). Unsupervised two-way hierarchical clustering with 5724 genes successfully classified tumors from normal mucosa, and displayed a distinctive MSI-H carcinomas subgroup. Based on intensive filtering, 57 known genes and eight ESTs were found to be highly relevant to the differentiation of MSI-H and MSS colorectal carcinomas. These genes successfully distinguish the new test set of six MSI-H and five MSS colorectal carcinomas. Many up- and downregulated genes in MSI-H colorectal carcinomas were related to the previously reported phenotypic characteristics; increased mucin production and intense peritumoral immune response in MSI-H carcinomas. Some of these differences were confirmed by semiquantitative reverse transcription-PCR and immunohistochemical analysis. Our findings indicate that there are many different genetic and transcriptomic characteristics between MSI-H and MSS colorectal carcinomas, and some of these differently expressed genes can be used as diagnostic or prognostic markers.