Bethesda Guidelines: Relation to Microsatellite Instability and MLH1 Promoter Methylation in Patients with Colorectal Cancer

BACKGROUND: Microsatellite instability (MSI) results from genetic and epigenetic changes. Studying Microsatellite instability can help in treatment and categorization of colorectal cancer (CRC) patients. OBJECTIVES: We aimed to investigate whether 14 genomic markers consisting of BAT-62, BAT-60, BAT-59a, BAT-56a, BAT-56b, DCD, RIOX, RNF, FOXP, ACVR, CASP2, HSP110, MT1X, and DNMT3a can increase the detection rate of MSI in CRC. METHODS: Samples were stratified by pentaplex panel (Promega) and 14 markers using multiplex PCR and fragment analysis. In MSI+ samples, to identify the pattern of BRAF V600E mutation and MLH1 promoter methylation, ARMS-scorpion, and Methylation-Specific High-Resolution Melting Curve analysis, were applied respectively. RESULTS: Totally, 35 MSI+ cases identified by 14 marker panel. Only 18 cases of them were detected by both panels which are pentaplex and 14 marker. On the other hand, 17 new MSI+ cases just were identified by 14 markers panel. The highest diagnostic value among 14 markers is related to three makers, namely DCD, MT1X, and DNMT3a. In MSI+ cases, the rate of MLH1 promoter methylation was insignificant, (P value = 0.3979) while the rate of observed BRAFV600E mutation was significantly higher (P value = 0.0002). CONCLUSION: Fourteen marker panel showed higher sensitivity in comparison with the pentaplex panel increasing the detection rate of MSI+ cases up to 1.94 fold. Three markers namely DNMT3a, DCD, and MT1X of 14 marker panel were the best among them showing excellent diagnostic value. A combination of these markers showed 100% sensitivity and specificity in the studied group. In contrary to the markers in the pentaplex panel, these markers had the ability to detect MSI without any bias for the clinicopathological features. These markers will help to identify more end-stage MSI+ tumors which are located distal colon.

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TUMOUR PATHOLOGY PREDICTS MICROSATELLITE INSTABILITY IN A POPULATION-BASED SERIES OF COLORECTAL CANCER CASES

Clinical & Investigative Medicine ◽

10.25011/cim.v31i4.4807 ◽

2008 ◽

Vol 31 (4) ◽

pp. 12

Author(s):

A J Hyde ◽

D Fontaine ◽

R C Green ◽

M Simms ◽

P S Parfrey ◽

...

Keyword(s):

Colorectal Cancer ◽

Lynch Syndrome ◽

Microsatellite Instability ◽

Population Based ◽

Pathological Features ◽

Predictive Tool ◽

Entire Cohort ◽

Dna Mismatch ◽

Bethesda Guidelines ◽

Revised Bethesda Guidelines

Background: Lynch Syndrome is an autosomal dominant trait that accounts forapproximately 3% of all cases of colorectal cancer (CRC). It is caused by mutations in DNA mismatch repair (MMR) genes, most commonly MLH1 or MSH2. These MMR defects cause high levels of microsatellite instability (MSI-H) in the tumours. MSI testing of all CRCs to identify potential Lynch Syndrome cases is not practical, so the Bethesda Guidelines, which use clinical and pathological features, were created to identify those tumours most likely to be MSI-H^1. In 2007 Jenkins et. al. created MsPath, a tool based on the pathological features described in the rarely used 3^rd Bethesda criterion, to improve prediction of MSI-H tumours among CRC cases diagnosed before age 60 years^2. Methods: We collected a population-based cohort of 716 CRC cases diagnosed before age 75 years in Newfoundland. For each of these cases we collected family history, performed MSI analysis, and scored a number of pathological features for the purpose of evaluating the accuracy of the Bethesda Criteria and MsPath at predicting MSI-H tumours. Results: Our work validates the MsPath tool in the Newfoundland population for the same age group used to create the tool. We found it identified MSI-H cases with a sensitivity of 95% and specificity of 35% in our population of CRCcases diagnosed before age 60 years (n=290). We also tested this tool on our older population of CRCcases, diagnosed at ages 60 to 74 years (n=426). We found it to be at least as predictive in this population,with a sensitivity of 95% and a specificity of 42%. We then used our entire cohort (N=716) to compare MsPath with the other Bethesda criteria.Bethesda criteria 1, 2, 4 and 5 together predicted MSI-H cases with a sensitivity of 67% and a specificity of 51%. MsPath was better at identifying these cases, with a sensitivity of 95% and a specificity of 39%. Conclusions: We conclude that MsPath can be extended to include patients diagnosed with CRC before age 75 years. As well, we have found that MsPath is a better predictive tool than the Revised Bethesda Guidelines for identifying MSI-H cases within a population-based setting of colorectal cancer. References: 1. Umar, A. et. al. J Natl Cancer Inst 2004;96:261-8 2.Jenkins, M.A. et. al. Gastroenterology 2007;133:48-56

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Pathology Features in Bethesda Guidelines Predict Colorectal Cancer Microsatellite Instability: A Population-Based Study

Gastroenterology ◽

10.1053/j.gastro.2007.04.044 ◽

2007 ◽

Vol 133 (1) ◽

pp. 48-56 ◽

Cited By ~ 205

Author(s):

Mark A. Jenkins ◽

Shinichi Hayashi ◽

Anne-Marie O’Shea ◽

Lawrence J. Burgart ◽

Tom C. Smyrk ◽

...

Keyword(s):

Colorectal Cancer ◽

Microsatellite Instability ◽

Population Based ◽

Population Based Study ◽

Bethesda Guidelines

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Microsatellite instability and MLH1 promoter hypermethylation in colorectal cancer

World Journal of Gastroenterology ◽

10.3748/wjg.v13.i12.1767 ◽

2007 ◽

Vol 13 (12) ◽

pp. 1867 ◽

Cited By ~ 24

Author(s):

Yaron Niv

Keyword(s):

Colorectal Cancer ◽

Microsatellite Instability ◽

Promoter Hypermethylation ◽

Mlh1 Promoter

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Methylation in p14ARF is Frequently Observed in Colorectal Cancer with Low-level Microsatellite Instability

Journal of International Medical Research ◽

10.1177/147323000903700408 ◽

2009 ◽

Vol 37 (4) ◽

pp. 1038-1045 ◽

Cited By ~ 8

Author(s):

K Kominami ◽

T Nagasaka ◽

HM Cullings ◽

N Hoshizima ◽

H Sasamoto ◽

...

Keyword(s):

Colorectal Cancer ◽

Microsatellite Instability ◽

Promoter Methylation ◽

Dna Methyltransferase ◽

Methylation Status ◽

Gene Promoters ◽

Braf Mutations ◽

Low Level ◽

Methylguanine Dna Methyltransferase ◽

High Level

Colorectal cancer (CRC) can be classified as high-level microsatellite instability (MSI-H), low-level MSI (MSI-L) and microsatellite stable (MSS) depending on levels of MSI. MSI-H CRC relies on a distinct molecular pathway due to the mismatch repair (MMR) deficiency and shows methylation in multiple gene promoters. The genetic pathway leading to MSI-L is unknown, although higher levels of promoter methylation are observed in this group compared with MSS CRCs. This study explored how promoter methylation affects MSI phenotype, by analysing the methylation status of eight CRC-related promoters, MSI phenotype and KRAS/BRAF mutations in a series of 234 CRCs. Promoter methylation of p14ARF was significantly related to MSI-L CRC with KRAS mutation. The MSI-H phenotype was related to methylation of MLH1 as expected, while the MSS phenotype was related to methylation of p16INK4a and O6-methylguanine-DNA methyltransferase, although this was not statistically significant. Thus, promoter methylation of p14ARF could be a significant alteration leading to CRC with MSI-L.

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Use of microsatellite instability in non-hereditary advanced colorectal cancer to predict response to chemotherapy and overall survival: A study of the Dutch Colorectal Cancer Group (DCCG)

Journal of Clinical Oncology ◽

10.1200/jco.2007.25.18_suppl.4118 ◽

2007 ◽

Vol 25 (18_suppl) ◽

pp. 4118-4118

Author(s):

M. Koopman ◽

G. A. Kortman ◽

L. Mekenkamp ◽

M. J. Ligtenberg ◽

N. Hoogerbrugge ◽

...

Keyword(s):

Colorectal Cancer ◽

Overall Survival ◽

Microsatellite Instability ◽

Early Stage ◽

Tissue Microarrays ◽

Primary Tumors ◽

Mlh1 Promoter ◽

Cancer Group ◽

Response To Chemotherapy ◽

Embedded Blocks

4118 Background: Microsatellite instability (MSI) is present in 10–20% of patients (pts) with non-hereditary colorectal cancer (CRC) and is generally associated with improved overall survival. The effect of chemotherapy in such pts is uncertain, and most data are derived from early stage CRC. Therefore the outcome of treatment in relation to presence or absence of MSI was studied in pts with non- hereditary advanced CRC. Methods: Data were collected from previously untreated advanced CRC pts randomized between 1st line capecitabine (Cap), 2nd line irinotecan (Iri), and 3rd line Cap + oxaliplatin (CapOx) vs 1st line CapIri and 2nd line CapOx. Formalin-fixed, paraffin embedded blocks of primary tumors and normal tissue were collected and tissue microarrays were made. Expression of the mismatch repair proteins MLH1, MSH2, MSH6 and PMS2 was examined by immunohistochemistry. Additionally MSI analysis and hypermethylation of the MLH1-promoter were performed. Pts with a tumor showing MSI caused by hypermethylation of the MLH1-promoter were included to study the correlation between MSI status and response to 1st line treatment and overall survival. Results: MSI caused by hypermethylation of the MLH1-promoter was found in 14 (3%) of 512 eligible pts. In 461 evaluable pts, disease control (CR+PR+SD=4 months) in 12 pts with MSI was 58% [95% CI 28%- 85%] and in 449 without MSI 83% [95% CI 79%-86%, p= 0.03].The median OS in pts with MSI was 7 months [95% CI 4–17] and in pts without MSI 18 months [95% CI 16–19, log rank p=0.08]. Conclusions: MSI in advanced non-hereditary CRC is very rare, and predicts a significantly worse outcome in terms of response to chemotherapy with a trend towards a decreased OS. No significant financial relationships to disclose.

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