Microsatellite Instability-high Cancers Research Articles

Genetic and epigenetic classifications define clinical phenotypes and determine patient outcomes in colorectal cancer

A molecular classification of colorectal cancer has been proposed based on microsatellite instability (MSI), CpG island methylator phenotype (CIMP), and mutations in the KRAS and BRAF oncogenes. This study examined the prevalence of these molecular classes, and differences in clinical presentation and outcome. Demographics, tumour characteristics and survival were recorded for 391 subjects with colorectal cancer. Tumour DNA was analysed for MSI (high (MSI-H) or microsatellite stable (MSS)), CIMP (high (CIMP-H) or no (CIMP-neg)) and BRAF and KRAS mutations. Clinical differences between four phenotypes were examined. Most tumours were MSS/CIMP-neg (69.8 per cent), with a nearly equal distribution of MSI-H/CIMP-H, MSI-H/CIMP-neg and MSS/CIMP-H types. MSS/CIMP-neg tumours were less likely to be poorly differentiated (P = 0.009). CIMP-H tumours were more common in older patients (P < 0.001). MSI-H/CIMP-H tumours had a high frequency of BRAF mutation and a low rate of KRAS mutation; the opposite was true for MSS/CIMP-neg tumours (P < 0.001). The four molecular phenotypes tended towards divergent survival (P = 0.067 for stages 1-III). MSI-H cancers were associated with better disease-free survival (hazard ratio 2.00 (95 per cent confidence interval 1.03 to 3.91); P = 0.040). Colorectal cancers are molecularly and clinically heterogeneous. These different molecular phenotypes may reflect variable prognosis.

RHAMM, p21 Combined Phenotype Identifies Microsatellite Instability-High Colorectal Cancers with a Highly Adverse Prognosis

The aim of this study was to identify prognostic subgroups of microsatellite instability-high (MSI-H) colorectal cancers by combined analysis of 10 well-established immunohistochemical tumor markers and 7 clinicopathologic features. Using a tissue microarray, immunohistochemistry was done on 223 cases of MSI-H cancers for the following protein markers: raf-1 kinase inhibitor protein, receptor for hyaluronic acid-mediated motility, apoptosis protease activating factor-1, mammalian sterile20-like kinase 1, p21, p27, p53, ephrin B2 receptor, Ki-67, and epidermal growth factor receptor. Seven clinicopathologic features and all tumor markers were evaluated in univariate and multivariable analyses. RHAMM overexpression [P < 0.001; hazard ratio [HR; 95% confidence interval (95% CI)], 3.86 (2.19-6.81)], loss of p21 [P = 0.002; 0.33 (0.16-0.67)], and higher N stage [P < 0.001; 3.31 (1.9-5.8)] were independent adverse prognostic factors. RHAMM/p21 combinations were evaluated by N stage. Significant differences in survival were observed with various RHAMM/p21 combinations (P < 0.001). Both node-negative and node-positive patients with RHAMM- tumors survived more than 120 months. Node-positive RHAMM+ patients had a strikingly worse prognosis [16.0 (10.0-63.0) months] and could further be divided into p21- patients [14.0 (9.0-27.0) months] and p21+ patients surviving 47.0 months. RHAMM+/p21- node-negative patients had a significantly shorter survival time than RHAMM+/p21+ tumors (P = 0.021). These results suggest that the combined phenotype of RHAMM and p21 expression is an invaluable independent prognostic immunohistochemical profile in MSI-H colorectal cancer. Based on the prognostic subgroups identified in our cohort, node-negative patients overexpressing RHAMM but with loss of p21 may derive a potential benefit from postoperative treatment, whereas adjuvant chemotherapy should be reconsidered for MSI-H node-positive RHAMM- tumors.

Specific Clinical and Biological Features Characterize Inflammatory Bowel Disease–Associated Colorectal Cancers Showing Microsatellite Instability

Microsatellite instability (MSI) due to mismatch repair (MMR) deficiency has been reported to occur at variable frequencies in inflammatory bowel disease-associated intestinal neoplasias (IBD-Ns). We investigated a large series of IBD-N for associations between MSI and several biologic and clinical parameters related to tumors, patients, and their treatment. A total of 277 IBD-Ns in 205 patients were screened for MSI. Biologic and clinical variables of patients with high levels of DNA microsatellite instability high (MSI-H) were collected and compared with those associated with 33 MSI-H non-IBD colorectal cancers (CRCs). A total of 27 IBD-Ns from 17 patients were found to be MSI-H. Compared with sporadic MSI-H CRCs, patients presented with a younger age at diagnosis, and there was no female predominance and no right-sided predominance. Unlike sporadic MSI-H CRCs, MSI-H IBD-Ns presented with heterogeneous mismatch repair defects involving MLH1, MSH2, MSH6, or PMS2, and a low frequency of MLH1 promoter methylation. They exhibited frequent BRAF mutations and frameshift mutations in genes containing coding repeat sequences. The mechanisms underlying MMR deficiency in MSI-H IBD-Ns are different from those in sporadic MSI-H tumors and seem to be more related to those observed in hereditary MSI-H tumors. However, BRAF mutations were observed in MSI-H IBD-Ns, similar to sporadic MSI-H tumors, but unlike hereditary MSI-H tumors. Finally, the mutational events in target genes for instability are the same in MSI-H IBD-N tumors as in non-IBD sporadic and hereditary colorectal MSI-H cancers, indicating a colon-related repertoire of target gene alterations.

Signet ring cell carcinoma of the colorectum: correlations between microsatellite instability, clinicopathologic features and survival

Colorectal cancer with microsatellite instability has a characteristic clinicopathologic profile, featuring right-sided, lymphocyte-rich tumors with a better prognosis than microsatellite stable (MSS) carcinoma. Mucinous and signet ring cell carcinomas are both over-represented among microsatellite instability-high cancers. The clinicopathologic features of mucinous microsatellite instability-high cancer parallel those of the overall microsatellite instability-high set, but it is not known whether the same is true for signet ring cell carcinoma, particularly given the fact that signet ring histology is a well-documented adverse prognostic factor. We recorded age, sex, tumor size, site, grade, stage, histologic pattern, growth pattern, Crohn-like reaction, vascular invasion and tumor-infiltrating lymphocytes in 72 resected signet ring cell carcinomas of the colorectum. Microsatellite instability was determined by a combination of polymerase chain reaction and immunohistochemical stains for hMLH1, hMSH2 and hMSH6. Tumors with instability at >30% of informative markers and/or loss of hMLH1 or hMSH2 expression were designated microsatellite instability-high; all others were classified as MSS. A total of 22 (31%) signet ring cell carcinomas were microsatellite instability-high. Compared to MSS signet ring cell carcinoma, they were more likely to be right-sided (81 vs 45%, P=0.005) and to affect older patients (68 vs 26%, P=0.0007) of female sex (59 vs 28%, P=0.03). Crohn-like reaction (45 vs 16%, P=0.02) and high tumor infiltrating lymphocyte counts (32 vs 8%, P=0.03) were more common in the microsatellite instability-high setting. There was no significant difference in 5-year survival in microsatellite instability-high vs MSS patients (41 vs 34%, P=0.3). In conclusion, approximately one-third of signet ring carcinomas of the colorectum are microsatellite instability-high. Microsatellite instability-high signet ring carcinomas share clinicopathologic features with other microsatellite instability-high cancers: older age group, female preponderance, right-sided location, Crohn-like reaction and numerous tumor-infiltrating lymphocytes. Microsatellite instability status does not appear to be a significant predictor of survival in signet ring cell carcinoma of the colorectum.

Lymphocyte-Rich Gastric Cancer: Associations with Epstein-Barr Virus, Microsatellite Instability, Histology, and Survival

Lymphocyte-rich gastric carcinomas may have a better prognosis than cancers without a pronounced host inflammatory response. Two subsets of gastric cancer—Epstein-Barr virus-positive and microsatellite instability high—have been associated with a lymphocyte-rich phenotype. We assessed relationships between tumor-infiltrating lymphocytes, Epstein-Barr virus status, microsatellite instability status, and cancer-specific survival in 110 resected gastric cancers. Seven patients had Epstein-Barr virus-positive cancer, including 4 (3.7%) of 107 consecutive patients. Tumors from 17 patients (16%) were designated microsatellite instability high on the basis of negative immunohistochemical staining for MLH1; all tumors had intact expression of MSH2 and MSH6. Epstein-Barr virus-positive cancers had increased tumor-infiltrating lymphocytes compared with Epstein-Barr virus-negative cancers (median 450/10 HPF versus 21/10 HPF, P < .001). Microsatellite instability–high cancers also had increased tumor-infiltrating lymphocytes compared with non–microsatellite instability–high cancers (median 150/10 HPF versus 20/HPF, P < .001). Microsatellite instability–high cancers affected older patients and were more likely to be intestinal in the Lauren classification and expanding in the Ming classification. By univariate analysis, decreased risk of death from gastric cancer was significantly associated with low tumor stage, expanding growth pattern, increasing tumor-infiltrating lymphocyte count, and microsatellite instability–high status. High tumor-infiltrating lymphocyte count and microsatellite instability–high status retained statistical significance as favorable prognostic factors after adjustment for tumor stage in multivariate analysis. Tumor-infiltrating lymphocyte count retained statistical significance as a favorable prognostic factor after adjustment for microsatellite instability–high status; but microsatellite instability–high status did not remain a significant independent prognosticator after adjustment for tumor-infiltrating lymphocyte count. The association between microsatellite instability–high cancers and high tumor-infiltrating lymphocyte counts may account for the association of microsatellite instability–high gastric cancers with improved survival.

APC mutation and tumour budding in colorectal cancer

Aim: To determine the frequency of tumour budding and somatic APC mutation in a series of colorectal cancers stratified according to DNA microsatellite instability (MSI) status. Material/Methods: Ninety five colorectal...

Neoplastic progression occurs through mutator pathways in hyperplastic polyposis of the colorectum

AIMColorectal cancer has been described in association with hyperplastic polyposis but the mechanism underlying this observation is unknown. The aim of this study was to characterise foci of dysplasia developing...

Towards a molecular classification of colorectal cancer.

The basic mechanisms driving genetic instability underlie a new molecular classification of colorectal cancer that is assuming diagnostic and prognostic importance. These mechanisms and the criteria for stratifying colorectal cancer as microsatellite stable (MSS), microsatellite instability-low (MSI-L) and microsatellite instability-high (MSI-H) are presented. This molecular classification is discussed in relation to morphogenesis, histopathology, behaviour and investigation of prognostic biomarkers in colorectal cancer. Clinical applications are considered, emphasising the role of the pathologist in identifying and working up cases of suspected hereditary non-polyposis colorectal cancer. The principal value of microsatellite instability testing is in relation to the diagnosis of hereditary non-polyposis colorectal cancer. Demonstration of loss of DNA mismatch repair genes, notably hMLH1 and hMSH2, by immunohistochemistry provides additional diagnostic information and may reduce the requirement for microsatellite instability testing. It is likely that testing for DNA mismatch repair will be adopted as a routine for colorectal cancer as more is learned of the distinctive pathobiology and behaviour of MSS, MSI-L and MSI-H cancers.