Microsatellite instability is associated with the histological features of the tumor in nonfamilial colorectal cancer.
ABSTRACT Replication errors (RERs) at microsatellite loci were examined in 46 specimens of nonfamilial colorectal cancer. Somatic microsatellite alterations in at least two genetic loci, D11S904, D13S175, D2S123, and D10S197, consistent with a RER(+) phenotype were found in four cases (8.7%). Six additional cases (13%) showed alterations at a single locus. Mucinous differentiation was observed in 3 of 4 (75%) adenocarcinomas with a RER(+) phenotype and only in 19% (8 of 42) of RER(-) adenocarcinomas (P < 0.05). A distinct cap of inflammatory cells at the advancing edge of the tumor and Crohn's-like reaction in peritumoral stroma were histologically identified in 50 and 25% of RER(+) and in 5 and 0% of RER(-) tumors, respectively (P < 0.05). Also, the plexiform pattern of growth of carcinoma turned out to be significantly associated with the RER(+) phenotype (P < 0.05). Mucinous differentiation and stromal inflammatory reactions are frequent features of hereditary nonpolyposis colorectal cancer in which germ-line mutations of mismatch repair genes cause genetic instability. Our results indicate that a link exists between such histological features and somatic genetic instability consistent with a RER(+) phenotype also in nonfamilial colorectal cancer.
Full-textDOI: · Available from: Gigliola Reato, May 29, 2015
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ABSTRACT: BACKGROUND Colorectal tumors with microsatellite instability (MSI) that do not comply with previously defined clinical criteria may be found in recently diagnosed hereditary nonpolyposis colorectal carcinoma families. Until recently, the indications for MSI testing were not clearly established. The objective of the current study was to validate the recently published Bethesda guidelines for MSI testing in a series of patients with apparently sporadic forms of colorectal carcinoma (CRC).METHODS Sixty-two patients with so-called sporadic CRC were included in the current study. MSI was analyzed at seven poly(CA) repeat sequences and at one poly(A) locus.RESULTSNine of 62 patients (14.5%) had tumors exhibiting MSI at ≥ 2 loci and 7 patients (11%) had MSI at ≥ 3 loci. Patients with MSI positive tumors were younger (P < 0.05), and their tumors more frequently were right-sided (P < 0.02) and more often exhibited a mucinous component (P < 0.05). The Bethesda guidelines were positive in 18% (11 of 62) of patients. The sensitivity of these guidelines in identifying tumors with MSI at ≥ 3 loci was 43% and the positive predictive value (PPV) was 27% (3 of 11 cases). Other variables were considered as alternative criteria to identify CRCs with MSI: age < 45 years and/or a right-sided tumor with a mucinous component. Using these 2 criteria alone, sensitivity increased to 85% and PPV to 46%.CONCLUSIONS In this study group, the use of three clinical criteria as sole indicators for MSI testing in patients with apparently sporadic forms of CRC were significantly more discriminating compared with the Bethesda guidelines, in addition to being substantially easier. Cancer 1999;85:779–85. © 1999 American Cancer Society.Cancer 01/1999; 85(4):779 - 785. DOI:10.1002/(SICI)1097-0142(19990215)85:4<779::AID-CNCR4>3.0.CO;2-C · 4.90 Impact Factor
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ABSTRACT: The optimal strategy for screening patients with colorectal carcinoma for Lynch syndrome (LS) is a subject of continued debate in the literature with some advocating universal screening while others arguing for selective screening. We evaluated 1292 colorectal carcinomas for DNA mismatch repair protein abnormalities and identified 150 (11.6%) tumors demonstrating high-levels of microsatellite instability (MSI-H). MSI-H colorectal carcinomas were divided into sporadic (112/1292, 8.7%) and LS/probable LS-associated (38/1292, 2.9%) groups based on BRAF V600E mutation, MLH1 promoter hypermethylation, cancer history, and germline mismatch repair gene mutation. All MSI-H colorectal carcinomas were analyzed for grade, location, and tumor histology. The utility of the revised Bethesda guidelines and published predictive pathology models for MSI-H colorectal carcinomas (PREDICT and MSPath) were evaluated. Left-sided MSI-H colorectal carcinomas were more frequently associated with LS compared with right-sided MSI-H colorectal carcinomas (12/21, 57% versus 26/129, 20%, P = .0008). There was no significant difference in histology between sporadic MSI-H and LS/probable LS-associated colorectal carcinomas except for a slightly higher proportion of sporadic MSI-H tumors demonstrating tumor-infiltrating lymphocytes (81% versus 61%, P = .015). Neither pathology predictive model identified all LS-associated colorectal carcinomas (PREDICT: 33/38, 87%; MSPath: 35/38, 92%). 12/117 (10%) MSI-H colorectal carcinomas identified in patients >60 years were LS/probable LS-associated. Our results demonstrate that models of predicting MSI-H fail to identify LS-associated colorectal carcinoma given their reliance on right-sided location. A significant proportion (32%) of LS-associated colorectal carcinoma is identified in patients >60 years. Finally, our results demonstrate similar morphologic features between LS-associated and sporadic MSI-H colorectal carcinomas.Human pathology 09/2013; DOI:10.1016/j.humpath.2013.06.012 · 2.81 Impact Factor
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ABSTRACT: Germline mutations of DNA mismatch repair (MMR) genes predispose Lynch syndrome mutation carriers to the development of MMR-deficient tumors. MMR-deficient tumors show high-level microsatellite instability (MSI-H) and are typically characterized by a comparatively favorable prognosis and the absence of distant organ metastasis. Lynch syndrome-associated cancers are characterized by a pronounced local anti-tumoral immune response and usually display dense lymphocyte infiltration. This finding strongly suggested that the immune system may play an active role in the surveillance and biology of these cancers. The progression of MMR deficient cancers seems to be triggered by mutations in microsatellite sequences within gene-encoding regions. These mutations may cause shifts of the translational reading frame and thus give rise to the generation of potentially immunogenic frameshift peptides (FSP) at the carboxy terminal end of the respective gene products. FSP-specific immune responses are thought to represent one major mechanism by which the host's adaptive immune system can recognize and potentially control Lynch syndrome-associated MSI-H cancers. Consequently, vaccination with FSP antigens represent a promising approach for treatment of Lynch syndrome-associated cancers, potentially also suitable for tumor prevention in so far tumor-free Lynch syndrome germ line mutation carriers. This review will summarize the molecular mechanisms contributing to the immunological phenotype of MSI-H cancers. In addition, clinical perspectives will be discussed, focusing on MSI-H cancer-associated FSP antigens as potential targets for immune therapy approaches.Familial Cancer 06/2013; 12(2). DOI:10.1007/s10689-013-9662-7 · 1.62 Impact Factor