Orginal CommunicationMicrosatellite instability in sporadic carcinomas of the proximal colon: Association with diploid DNA content, negative protein expression of p53, and distinct histomorphologic features☆,☆☆
Section snippets
Tumor material
Genomic DNA for polymerase chain reaction (PCR) was isolated from cryoconserved tumor tissue by standard extraction methods.7 Genomic DNA from matched normal mucosa was used as reference. Twenty adenocarcinomas of the cecum and ascending colon (right side) were included in this study. The specimens dated from the years 1991 through 1993 and were preserved at random. Conventional histopathologic parameters, such as tumor extension, differentiation, and extracellular mucin production, had been
Microsatellite instability
MIN was found in 7 (35%) of the 20 adenocarcinomas of the cecum and ascending colon. All seven MIN-positive tumors revealed alterations at the loci D2S123 and D18S42, four of them had instabilities at three loci, two in all four loci, and one tumor in two loci (Table I). Examples of MIN, observed as extra bands in the tumor DNA compared with the corresponding normal tissue DNA, are illustrated in Fig. 1.
Discussion
A comprehensive study was performed on 20 sporadic adenocarcinomas of the cecum and ascending colon to assess the association of MIN, DNA content, and p53 protein expression with particular clinical and histomorphologic features of the tumors. Comparison of MIN-positive with MIN-negative colonic carcinomas in our series was restricted to tumors of the proximal colon because approximately 90% of all MIN-positive tumors were found in the proximal colon, and differences between right- and
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2007, Surgical OncologyCitation Excerpt :The majority (60–80%) of colorectal tumours in HPCC arise on the right side of colon (proximal to the splenic flexure): in comparison, only 23–32% of sporadic colorectal cancers are right sided [42]. It affected individuals, the risk of synchronous and metachronous colorectal cancers approaches 45% within 10 years of surgical resections [43,44]. On histological examination, HNPCC colorectal cancers tend to be poorly differentiated, abundant in extracellular mucin, and distinguished by a lymphoid host response to the tumour [45,46].
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Supported by Deutsche Krebshilfe, Dr. Mildred Scheel Stiftung (Az: W7/95/Wu3) and Deutsche Forschungsgemeinschaft (Az: Fo 239/1-1).
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Reprint requests: Bernd Wullich, MD, Clinic of Urology and Pediatric Urology, Saarland University, 66421 Homburg, Germany.