Search results for "microsatellite instability"
showing 10 items of 69 documents
Testing for Lynch Syndrome in Endometrial Carcinoma: From Universal to Age-Selective MLH1 Methylation Analysis
2022
Simple Summary International guidelines recommend universal screening of endometrial carcinoma patients for Lynch syndrome, a hereditary cancer predisposition syndrome. Screening is based on mismatch repair protein immunohistochemistry and reflex MLH1 methylation analysis to exclude the likely sporadic cases of MMR deficiency. As sporadic MLH1 protein loss is common in endometrial carcinoma, the ability to target methylation testing would save efforts and costs. We discovered that limiting methylation testing to patients under 65 years would have significantly reduced the testing effort while maintaining a low false negative rate for MLH1-LS detection (0% and 3% in our clinic and registry-b…
Thymidylate synthase polymorphism and microsatellite instability: association in colorectal cancer.
2005
5-Fluorouracil (5FU) is the main drug used for the treatment of colorectal cancer (CRC) and Thymidilate Synthase (TS) is its target enzyme. TS gene has regulatory tandemly repeated sequences in its 5'' and 3''untraslated region (5''-3'' UTR). CRC often shows a kind of genomic instability called Microsatellite Instability (MSI) that is associated with TS levels and survival. Our data show that the genotype 2R/2R (homozygosity for 2 tandem repeat sequences in the 5''UTR) is more frequently associated with MSI+ and lower TS levels. More over we did not find any significant association between the 2R/3R (heterozygosity for 2 and 3 tandem repeat sequences in the 5''UTR) and 3R/3R (homozygosity f…
Somatic mutation profiles as molecular classifiers of ulcerative colitis-associated colorectal cancer.
2021
Ulcerative colitis increases colorectal cancer risk by mechanisms that remain incompletely understood. We approached this question by determining the genetic and epigenetic profiles of colitis-associated colorectal carcinomas (CA-CRC). The findings were compared to Lynch syndrome (LS), a different form of cancer predisposition that shares the importance of immunological factors in tumorigenesis. CA-CRCs (n=27) were investigated for microsatellite instability, CpG island methylator phenotype, and somatic mutations of 999 cancer-relevant genes ("Pan-cancer" panel). A subpanel of "Pan-cancer" design (578 genes) was used for LS colorectal tumors (n=28). Mutational loads and signatures stratifie…
Familial risk-colorectal cancer: ESMO Clinical Practice Guidelines.
2013
J. Balmana1, F. Balaguer2, A. Cervantes3 & D. Arnold4, on behalf of the ESMO Guidelines Working Group* Department of Medical Oncology, Hospital Vall d’Hebron, Vall d’Hebron Institute of Oncology (VHIO), Universitat Autonoma de Barcelona, Barcelona; Department of Gastroenterology, Hospital Clinic, CIBERehd, IDIBAPS, University of Barcelona, Barcelona; Department of Hematology and Medical Oncology, INCLIVA, University of Valencia, Valencia, Spain; Department of Medical Oncology, Tumor Biology Clinic, Albert Ludwigs University, Freiburg, Germany;
The TP53 colorectal cancer international collaborative study on the prognostic and predictive significance of p53 mutation: influence of tumor site, …
2005
Purpose The aims of the TP53 Colorectal Cancer (CRC) International Collaborative Study were to evaluate the possible associations between specific TP53 mutations and tumor site, and to evaluate the prognostic and predictive significance of these mutations in different site, stage, and treatment subgroups. Patients and Methods A total of 3,583 CRC patients from 25 different research groups in 17 countries were recruited to the study. Patients were divided into three groups according to site of the primary tumor. TP53 mutational analyses spanned exons 4 to 8. Results TP53 mutations were found in 34% of the proximal colon tumors and in 45% of the distal colon and rectal tumors. They were assoc…
The Different Immune Profiles of Normal Colonic Mucosa in Cancer-Free Lynch Syndrome Carriers and Lynch Syndrome Colorectal Cancer Patients.
2021
ABSTRACT Background and aims Due to the high load of immunogenic frameshift neoantigens, tumors arising in individuals with Lynch syndrome (LS), the most common inherited colorectal cancer (CRC) syndrome, are characterized by a pronounced immune infiltration. However, the immune status of normal colorectal mucosa in LS is not well characterized. We assessed the immune infiltrate in tumor-distant normal colorectal mucosa from LS CRC patients, sporadic microsatellite-unstable (MSI) and microsatellite-stable (MSS) CRC patients, and cancer-free LS carriers. Methods CD3-positive, FOXP3-positive and CD8-positive T cells were quantified in 219, 233 and 201 formalin-fixed paraffin-embedded (FFPE) n…
DNA methylation changes and somatic mutations as tumorigenic events in Lynch syndrome-associated adenomas retaining mismatch repair protein expression
2018
Background: DNA mismatch repair (MMR) defects are a major factor in colorectal tumorigenesis in Lynch syndrome (LS) and 15% of sporadic cases. Some adenomas from carriers of inherited MMR gene mutations have intact MMR protein expression implying other mechanisms accelerating tumorigenesis. We determined roles of DNA methylation changes and somatic mutations in cancer-associated genes as tumorigenic events in LS-associated colorectal adenomas with intact MMR. Methods: We investigated 122 archival colorectal specimens of normal mucosae, adenomas and carcinomas from 57 LS patients. MMR-deficient (MMR-D, n 49) and MMR-proficient (MMR-P, n 18) adenomas were of particular interest and were inter…
Retinoblastoma epidemiology: Does the evidence matter?
2007
It has been proposed that retinoblastoma is 'caused' by two sequential mutations affecting the RB1 gene, but this is a rather outdated view of cancer aetiology that does not take into account a large amount of new acquisitions such as chromosomal and epigenetic alterations. Retinoblastoma remains probably the only cancer in which the rather simplistic 'two hit' mutational model is still considered of value, although cancer is known to be associated with genomic and microsatellite instability, defects of the DNA mismatch repair system, alterations of DNA methylation and hystone acethylation/deacethylation, and aneuploidy. Moreover, as it is shown herein, the predictions made by the 'two hit'…
In the literature: April 2020
2020
Deficient DNA mismatch repair (dMMR) may be caused by germline or somatic mutations in mismatch repair genes ( MLH1 , MSH2 , MSH3 , MSH6 and PMS2 ) or through epigenetic silencing of MLH1 .1 dMMR induces a hypermutator phenotype, also known as microsatellite instability (MSI). Next-generation sequencing identifies MSI in 12 cancer types. The highest prevalence is seen in endometrial cancer (31.4%), followed by colorectal cancer (19.7%) and gastric cancer (GC, 19.1%). MSI was related to better prognosis for colorectal cancer and GC . Moreover, the dMMR/MSI hypermutator phenotype is thought to produce large numbers of immunogenic neoantigens that can be recognised by immune cells, leading to …
Assessing molecular subtypes of gastric cancer: microsatellite unstable and Epstein-Barr virus subtypes. Methods for detection and clinical and patho…
2018
Background The molecular classification of gastric cancer recognises two subtypes prone to immune checkpoint blockade: the microsatellite unstable and the Epstein-Barr virus (EBV)-related tumours. We aim to assess the concordance between immunohistochemistry and PCR for microsatellite status evaluation, and explore the value of microsatellite instability (MSI) and EBV as predictive survival factors. Material and methods We collected 246 consecutively diagnosed gastric cancer cases in all stages and evaluated the microsatellite status using immunohistochemistry for mismatched repair (MMR) proteins and PCR. EBV expression was studied through in situ hybridisation. Results Forty-five (18%) cas…