Microsatellite Instability and Clinicopathologic Significance in Colon Cancer Patients

PURPOSE: Colon cancer shows various genetic alterations in its development and progression. Recently, microsatellite instability (MSI) has been related to a novel mechanism of carcinogenesis, and might be a useful prognostic factor in several gastrointestinal malignancies. The loss of heterozygosity (LOH) is known to be related with the allelic loss of various tumor suppressor genes, however, MSI, which has been found to result from an erroneous DNA mismatch repair system, has been known to be involved in the carcinogenesis of hereditary non-polyposis colon cancers and some aspects of sporadic colorectal cancers. In this study, the status of MSI was examined in sporadic colon cancers, and its correlation with various clinico-pathological parameters investigated. METHODS: Fifty sporadic colorectal cancers, treated by surgery alone, were analyzed for the presence of MSI using microsatellite markers, and tumor and normal DNA, obtained from formalin-fixed paraffin-embedded archival tissues. MSIs were examined at the BAT25, BAT26, D2S123, D5S346 and D17S250 loci, as recommended in the 1997 NIH International Workshop on Microsatellite Instabilities and RER phenotypes. RESULTS: MSI was detected in 11 cases (22%), and was more frequently detected in the non-metastatic adenocarcinoma and Astler-Coller stages A+B1+C1 groups than in the metastatic and B2+C2+D groups. Also, there were no metastatic cases in the MSI-high group, where more than 3 loci had MSI. LOH was detected in three of the recommended markers, and was observed in 17 cases (34%). LOH was more highly detected in the metastatic and B2+C2+D groups, but there was no correlation with the clinico-pathological parameters. However, no LOH-positive cases were found in the MSI-positive group. CONCLUSION: These results suggest that MSI may be partially involved in colorectal carcinogenesis and the metastasis mechanism. Also, the clinical use of the MSI status may help in determining the prognosis of colorectal cancer patients.

Relaparotomy Following a Resection for Gastric Cancer

BACKGROUND: There has been a general feeling among surgeons that recurrence or metastasis following a curative gastric resection is a hopeless surgical proposition. This study was conducted to evaluate the clinical features and significance of relaparotomy following a gastrectomy for gastric cancer. METHODS: Fifty-six cases of relaparotomies following resection for 53 gastric cancer patients, which were performed over a nine-year period, were investigated retrospectively. On preoperative diagnosis, there were 17 cases of remnant and anastomotic recurrence, 15 cases of intestinal obstruction, 7 cases of cholecystitis, 7 cases of rectosigmoid obstruction, 5 cases of E-loop obstruction and 5 cases of other diseases. RESULTS: Of all the laparotomies eleven cases (19%) were non-recurrence, benign diseases and forty-six (81%) were recurrence. In the 17 cases of remnant and anastomotic recurrence, re-resection was possible in 13 (76%) and major postoperative complications developed in 4 cases with 2 cases of death within one month. Also 6 of 7 re-resected cases which was stage I at first operation were still alive well. In 15 cases of mechanical obstruction, 5 cases were non-recurrence and 10 cases involved recurrence, of which 6 had a bypass or enterostomy and 4 an exploration only. All cholecystitis cases had a cholecystectomy; metastasis was found in 2 cases. Rectal obstruction and E-loop obstruction all involved recurrence and a palliative resection was possible in only one case of each type of obstruction. CONCLUSIONS: In a relaparotomy of remnant and anastomotic recurrence, most of the survival-improving re-resection cases were in stage I at the first operation. In late-onset cholecystitis tumor recurrence should be suspected and a relaparotomy of the malignant obstruction, with bypass and ostomy procedure, can be justified for symptomatic relief.