Lynch Syndrome Colorectal Cancer Research Articles

Referral of Queensland women with endometrial cancer to genetic services

Approximately 5% of all endometrial cancers are due to a hereditary disposition, and a majority of the cases were found in families with Lynch syndrome or hereditary non-polyposis colorectal cancer (HNPCC) syndrome. Whilst both men and women with Lynch syndrome have a significantly increased risk of developing colorectal cancer (18-69%), women face the additional lifetime risks of developing endometrial cancer – between 27% to 71% as compared to 2% in the Australian general population. Despite the increased risk, many eligible women who may benefit from genetic assessment are not being referred by their treating clinician. The purpose of this study is to evaluate the patterns of referral of women diagnosed with endometrial cancer to genetic services. Using the diagnostic, clinical and referral databases from three different sites, we were able to link data of endometrial cancer cases in Queensland from May 2005 to December 2007. We determined the percentage of women diagnosed with endometrial cancer who could have been referred based on at least one risk factor suggestive of Lynch syndrome, the percentage of women that were referred and the percentage of women that attended genetic services. The revised Amsterdam and Bethesda criteria guidelines were adapted and used to assess the appropriateness of referral. Preliminary results show that of the 955 new diagnosis of endometrial cancer, 29 women (3%) were referred and 17 (1.8%) attended. This suggests that women who may benefit from genetic assessment do not ultimately attend their scheduled appointment. The mean age of referral is 61.7 years, with seven women diagnosed under the age of 50. Of the seven women, three were found to be mutation carrier. The results will be used to improve identification and referral of women at risk of Lynch syndrome to genetic health services in Queensland, and to increase awareness of hereditary gynaecological cancer.

8q23.3 and 11q23.1 as modifying loci influencing the risk for CRC in Lynch syndrome

Recently, Houlle et al1 reported results of two modifier SNPs in Lynch syndrome, rs16892766 on 8q23.3 and rs3802842 on 11q23.1 previously identified as low-susceptibility colorectal cancer (CRC) loci, challenging earlier reported findings.2, 3 In 2009 Wijnen et al2 demonstrated that two SNPs located on 8q23.3 (rs16892766) and 11q23.1 (rs3802842) were associated with an increased risk of developing CRC in Dutch Lynch syndrome patients. The study revealed that patients' homozygote for SNP rs16892766 were associated with an elevated risk of CRC in a dose-dependent manner with a 2.16-fold increased risk of developing CRC, whereas the variant (CC) genotype of SNP rs3802842 was associated with an increased risk of CRC in female carriers only (HR=3.08).2 In a combined analysis of the two SNPs, the risk was significantly associated with the number of risk alleles and the effect was shown to be stronger in female carriers than in male carriers. Recently, Talseth-Palmer et al3 confirmed the increased risk of CRC in Lynch syndrome patients in a combined Australian and Polish sample cohort but only in MLH1 mutation carriers. In this study the two Lynch syndrome populations (Australian and Polish) were analysed separately and together, as a larger sample size gives increased power and more reproducible results. SNP rs3802842 revealed a significant association on the risk of developing CRC in the combined sample population (Australian and Polish) with a HR of 2.67. When analysed separately, the Australian sample population displayed significant results whereas the Polish sample population displayed a trend, which demonstrates the increased power acquired when more samples are analysed together. SNP rs16892766 was only significantly associated with the increased risk of CRC in Australian MLH1 mutation carriers, but as this was the same SNP that displayed an association in the Dutch study2 we also analysed the additive effect of the two SNPs. We were able to show that MLH1 mutation carriers from Australia and Poland harbouring three risk alleles for the two SNPs developed CRC on average 24 years younger and were at 5.52-fold increased risk of CRC compared with individuals harbouring no risk alleles. The quote in the report by Houlle et al1 ‘During the submission of this study, Talseth-Palmer et al15 reported that in MLH1 carriers, but not in MSH2 carriers, the 11q23.1 CC and 8q23.3 AC genotypes were associated with an increased risk, but this significant association detected in 373 Australian mutation carriers was not found in 311 Polish mutation carriers analysed in the same study' is incorrect, as we did see this association in our combined sample cohort. A decreased risk of CRC (HR=0.267, P=0.0271) for the CC (variant) genotype for SNP rs16892766 is reported by Houlle et al.1 According to previously published results discussed above this result is contradictory. A decreased risk of CRC indicate a later age of onset of CRC in the two individuals who harboured the CC genotype for SNP rs16892766, but the age of onset of CRC of these two individuals was not reported and can therefore not be commented on. It is highlighted by the French authors that the small number of subjects harbouring this genotype could affect the reported results. We believe that the observed results could be due to the fact that either of these two individuals harbours the variant (CC) genotype for SNP rs3802842, which seems to be important for the increased risk of CRC as observed in the Australian/Polish sample cohort. A meta-analysis of the French and Dutch data set was performed by Houlle et al1 indicating that SNP rs3802842 at 11q23.1 is not associated with increased risk of developing CRC, and the only association observed in this meta-analysis was a decreased risk of CRC for SNP rs16892766 in male mutation carriers, which contradicts previously reported results.2, 3 SNP rs16892766 (8q23.3) did not show an association with the CC (variant) genotype for the overall sample size as shown on the Forest plot (Figure 11), which is not surprising as positive and negative results combined will end up with a neutral result. But false positive results in the Dutch study2 and false negative results in the French study1 cannot be ruled out as a reason for the neutral results observed in the meta-analysis. Also, the heterogeneity of the population (ie, MMR gene) is not taken into account when a meta-analysis is performed and as shown by Talseth-Palmer et al3 this can drastically affect the observed results.

DNA repair gene polymorphisms and risk of early onset colorectal cancer in Lynch syndrome

DNA repair plays a pivotal role in maintaining genomic integrity with over 130 genes involved in various repair pathways that include base excision repair, nucleotide excision repair, double strand break repair and DNA mismatch repair. Polymorphisms within genes that are involved in these processes have been widely reported to be associated with cancer susceptibility in an extensive range of malignancies that include colorectal cancer (CRC). Lynch syndrome is caused by inherited germline mutations in DNA mismatch repair genes, predominantly in MLH1 and MSH2, that predispose to a variety of epithelial malignancies, most notably CRC. Despite being a relatively well understood hereditary cancer syndrome there remain several questions in relation to genetic influences on disease expression. Since Lynch syndrome is associated with a breakdown in DNA mismatch repair variation in other DNA repair genes may influence disease expression. In this report we have genotyped 424 Australian and Polish Lynch syndrome participants for eight common DNA repair gene polymorphisms to assess any association with the age of CRC onset. The DNA repair gene SNPs included in the study were: BRCA2 (rs11571653), MSH3 (rs26279), Lig4 (rs1805386), OGG1 (rs1052133), XRCC1 (rs25487), XRCC2 (rs3218536 and rs1799793) and XRCC3 (rs861539). Cox multi-variant regression modelling failed to provide any convincing evidence of an effect in any of the polymorphisms analysed. The data suggest that polymorphisms in DNA repair genes do not contribute to cancer risk in a population of CRC patients who are at increased risk of disease as a result in a deficiency of DNA mismatch repair.

Screening for Lynch Syndrome in Colorectal Cancer: Are We Doing Enough?

The purpose of this study was to assess the efficacy of screening for the detection of Lynch syndrome (LS) in an unselected population undergoing surgery for a colorectal cancer. A total of 1,040 patients were prospectively included between 2005 and 2009. LS screening modalities included the Bethesda criteria, immunochemistry (IHC) for MLH1, MSH2, and MSH6, and microsatellite instability (MSI) by using pentaplex markers. Promoter methylation was assessed in tumors with a loss of MLH1 expression. Gene sequencing was offered to patients with abnormal IHC or MSI status without promoter methylation. A total of 105 patients had an abnormal result: 102 (9.8%) exhibited a loss of protein on IHC and 98 (9.4%) had MSI. A discordant result was observed in 10 patients with eventual proven LS in 6 patients. Loss of MLH1 (n = 64) was due to promoter methylation in 43 patients (67.2%). Overall, of 62 patients with an abnormal result, 38 had genetic sequencing leading to 25 (65.8%) identified with a germ-line mutation. Loss of MSH2 on IHC was associated with a mutation in 78.3% (18 of 23) of cases. Among the 62 patients with abnormal results, 23 (37.1%) did not meet the Bethesda criteria. Strict application of the Bethesda criteria does not lead to identification of all patients with LS. IHC and MSI testing are complementary methods and should be used in association to identify potential LS patients.

Comparison between universal molecular screening for Lynch syndrome and revised Bethesda guidelines in a large population-based cohort of patients with colorectal cancer

BackgroundThe selection of patients for genetic testing to rule out Lynch syndrome is currently based on fulfilment of at least one of the revised Bethesda criteria followed by mismatch repair...

Association of low‐risk MSH3 and MSH2 variant alleles with Lynch syndrome: Probability of synergistic effects

Mutations in the MLH1 and MSH2 genes account for a majority of cases of families with Lynch Syndrome. Germ-line mutations in MSH6, PMS2 and MLH3 are responsible for disease in a minority of cases, usually associated with milder and variable phenotypes. No germ-line mutations in MSH3 have so far been associated with Lynch Syndrome, although it is known that impaired MSH3 activity leads to a partial defect in mismatch repair (MMR), with low levels of microsatellite instability at the loci with dinucleotide repeats in colorectal cancer (CRC), thus suggesting a role for MSH3 in carcinogenesis. To determine a possible role of MSH3 as predisposing to CRC in Lynch syndrome, we screened MSH3 for germ-line mutations in 79 unrelated Lynch patients who were negative for pathogenetic mutations in MLH1, MSH2 and MSH6. We found 13 mutant alleles, including silent, missense and intronic variants. These variants were identified through denaturing high performance liquid chromatography and subsequent DNA sequencing. In one Lynch family, the index case with early-onset colon cancer was a carrier of a polymorphism in the MSH2 gene and two variants in the MSH3 gene. These variants were associated with the disease in the family, thus suggesting the involvement of MSH3 in colon tumour progression. We hypothesise a model in which variants of the MSH3 gene behave as low-risk alleles that contribute to the risk of colon cancer in Lynch families, mostly with other low-risk alleles of MMR genes.

Challenging cases encountered in colorectal cancer screening for Lynch syndrome reveal novel findings: nucleolar MSH6 staining and impact of prior chemoradiation therapy

Many pathology laboratories have developed specific screening protocols to detect patients with Lynch syndrome. With recent recommendations to test all patients with newly diagnosed colorectal cancer for Lynch syndrome, the volume of testing will increase, and the most economic and reliable screening test will prevail. Although the detection of microsatellite instability by polymerase chain reaction and the detection of loss of the mismatch repair proteins by immunohistochemistry can each be used as a screening tool, each methodology has its strengths and weaknesses. During the time of our study, we used both polymerase chain reaction and immunohistochemistry to screen for Lynch syndrome in colorectal cancer specimens. We encountered 21 cases that posed significant interpretive challenges. A previously unpublished pattern of nucleolar MSH6 staining and potential spurious results induced by chemoradiation therapy are described. We feel that it is important to report these cases so that potential pitfalls in screening for Lynch syndrome can be avoided.

Tumour-specific methylation of PTPRG intron 1 locus in sporadic and Lynch syndrome colorectal cancer

DNA methylation is a hallmark in a subset of right-sided colorectal cancers. Methylation-based screening may improve prevention and survival rate for this type of cancer, which is often clinically asymptomatic in the early stages. We aimed to discover prognostic or diagnostic biomarkers for colon cancer by comparing DNA methylation profiles of right-sided colon tumours and paired normal colon mucosa using an 8.5 k CpG island microarray. We identified a diagnostic CpG-rich region, located in the first intron of the protein-tyrosine phosphatase gamma gene (PTPRG) gene, with altered methylation already in the adenoma stage, that is, before the carcinoma transition. Validation of this region in an additional cohort of 103 sporadic colorectal tumours and 58 paired normal mucosa tissue samples showed 94% sensitivity and 96% specificity. Interestingly, comparable results were obtained when screening a cohort of Lynch syndrome-associated cancers. Functional studies showed that PTPRG intron 1 methylation did not directly affect PTPRG expression, however, the methylated region overlapped with a binding site of the insulator protein CTCF. Chromatin immunoprecipitation (ChIP) showed that methylation of the locus was associated with absence of CTCF binding. Methylation-associated changes in CTCF binding to PTPRG intron 1 could have implications on tumour gene expression by enhancer blocking, chromosome loop formation or abrogation of its insulator function. The high sensitivity and specificity for the PTPRG intron 1 methylation in both sporadic and hereditary colon cancers support biomarker potential for early detection of colon cancer.

Colorectal Cancer Survival Advantage in MUTYH-Associated Polyposis and Lynch Syndrome Families

The cardinal features of colorectal cancer in patients with the MUTYH-associated polyposis syndrome, featured in this editorial, are of very recent discovery and remain under review as new clinical phenotypes for these patients are still being identified. Importantly, its phenotype results from homozygosity of the MUTYH gene and, therefore, is inherited in an autosomal recessive pattern. In a more intensively studied hereditary colorectal cancer syndrome, namely Lynch syndrome, the cardinal features have been shown to result from an autosomal dominantly inherited pattern and includes earlier average age of cancer onset, when compared with the general population (45 years for Lynch syndrome colorectal cancer and 64 years for patients with colorectal cancer in the general population), accelerated carcinogenesis, high risk for metachronous colorectal cancers, specific pathology features for Lynch syndrome colorectal cancers that are more often poorly differentiated and have an excess of Colorectal Cancer Survival Advantage in MUTYH-Associated Polyposis and Lynch Syndrome Families

Informed Decisions Regarding Microsatellite Instability Testing: Need for an Intention-to-Screen Analysis

informed consent on microsatellite instability (MSI) testing in patients with colorectal cancer (CRC) who have suspected Lynch syndrome met the primary end point: a CD-ROM–assisted intervention had a positive impact on the education of patients. However, in our opinion, the authors’ conclusions on the secondary outcomes suffer from a substantial selection bias. They suggest that decisional and emotional distress were negligible among patients who accepted to be randomly assigned, which ignores that more than one third of patients denied participation in the study. Although this regards secondary end points, it is relevant for medical oncologists, because it pertains to daily practice. We think that the logical hierarchy of the issues related to advising patients with CRC about MSI testing is as follows: whether to do that; when to do that; who should do that; and how to do that. Testing for MSI is becoming more and more popular. Some experts suggest to perform universal MSI testing on all patients with newly diagnosed CRC, regardless of age and family history. 2 This is because regular surveillance is of clinical benefit for relatives at risk. 3 In contrast, the benefit of such testing for individual patients with CRC has not been definitively proven: the type of surgery and chemotherapy are the same for patients with sporadic and Lynch syndrome CRC, 4 but the follow-up may be different (ie, the issue of whether to do that). Mastering the clinical implications of MSI testing and sharing them with our patients constitute prohibitive challenges for the oncologists. The patients themselves, who often want to concentrate on the treatment of their cancer, present a challenge as well (ie, the issues of when and who). Recent guidelines and policy statements from both the United

Clearing the Air on Smoking and Colorectal Cancer

Clearing the Air on Smoking and Colorectal Cancer

A back-to-back comparison of white light video endoscopy with autofluorescence endoscopy for adenoma detection in high-risk subjects

ObjectiveTo compare the sensitivity of autofluorescence endoscopy (AFE) and white light video endoscopy (WLE) for the detection of colorectal adenomas in high-risk patients belonging to Lynch syndrome (LS) or familial...

1030 Somatic Hypermethylation of MSH2 is a Frequent Event in Lynch Syndrome Colorectal Cancers

1030 Somatic Hypermethylation of MSH2 is a Frequent Event in Lynch Syndrome Colorectal Cancers

Report From the Jerusalem Workshop on Lynch Syndrome-Hereditary Nonpolyposis Colorectal Cancer

A Workshop was held in Jerusalem, Israel, on October 26 and 27, 2009 to discuss the management of Lynch syndrome-hereditary nonpolyposis colorectal cancer (CRC), with the primary goal to develop consensus for the optimal management of this disease. A second goal was to identify areas of research with the potential to advance the clinical management of Lynch syndrome. The perspectives and recommendations from the workshop are meant to be a platform for discussion and deliberation. The Workshop was organized by Moshe Shike (Memorial Sloan Kettering Cancer Center, New York) and sponsored by The Colon Cancer Foundation. More details of each presentation are available in an on-line supplement.

Somatic Hypermethylation of MSH2 Is a Frequent Event in Lynch Syndrome Colorectal Cancers

Heritable germline epimutations in MSH2 have been reported in a few Lynch syndrome families that lacked germline mutations in the MSH2 gene. It is not known whether somatic MSH2 methylation occurs in MSH2 mutation-positive Lynch syndrome subjects or sporadic colorectal cancers (CRC). Therefore, we determined the methylation status of the MSH2 gene in 268 CRC tissues, including 222 sporadic CRCs and 46 Lynch syndrome tumors that did not express MSH2. We also looked for microsatellite instability (MSI), germline mutations in the MSH2 and EpCAM genes, somatic mutations in BRAF and KRAS, and the CpG island methylator phenotype (CIMP). We observed that somatic MSH2 hypermethylation was present in 24% (11 of 46) of MSH2-deficient (presumed Lynch syndrome) tumors, whereas no evidence for MSH2 methylation existed in sporadic CRCs (MSI and microsatellite stable) or normal colonic tissues. Seven of 11 (63%) patients with MSH2 methylation harbored simultaneous pathogenic germline mutations in the MSH2 gene. Germline EpCAM deletions were present in three of four patients with MSH2 methylation but without pathogenic MSH2 germline mutations. The mean methylation scores at CIMP-related markers were significantly higher in Lynch syndrome tumors with MSH2 methylation than MSH2-unmethylated CRCs. In conclusion, our data provide evidence for frequent MSH2 hypermethylation in Lynch syndrome tumors with MSH2 deficiency. MSH2 methylation in this subset of individuals is somatic and may serve as the "second hit" at the wild-type allele. High levels of aberrant methylation at CIMP-related markers in MSH2-methylated tumors raise the possibility that MSH2 is a target susceptible to aberrant methylation in Lynch syndrome.

Smoking and Colorectal Cancer in Lynch Syndrome: Results from the Colon Cancer Family Registry and The University of Texas M.D. Anderson Cancer Center

Lynch syndrome family members with inherited germline mutations in DNA mismatch repair (MMR) genes have a high risk of colorectal cancer (CRC), and cases typically have tumors that exhibit a high level of microsatellite instability (MSI). There is some evidence that smoking is a risk factor for CRCs with high MSI; however, the association of smoking with CRC among those with Lynch syndrome is unknown. A multicentered retrospective cohort of 752 carriers of pathogenic MMR gene mutations was analyzed, using a weighted Cox regression analysis, adjusting for sex, ascertainment source, the specific mutated gene, year of birth, and familial clustering. Compared with never smokers, current smokers had a significantly increased CRC risk [adjusted hazard ratio (HR), 1.62; 95% confidence interval (95% CI), 1.01-2.57] and former smokers who had quit smoking for 2 or more years were at decreased risk (HR, 0.53; 95% CI, 0.35-0.82). CRC risk did not vary according to age at starting. However, light smoking (<10 cigarettes per day) and shorter duration of smoking (<10 years) were associated with decreased CRC risk (HR, 0.51; 95% CI, 0.29-0.91 and HR, 0.52; 95% CI, 0.30-0.89, respectively). For former smokers, CRC risk decreased with years since quitting (P trend <0.01). People with Lynch syndrome may be at increased risk of CRC if they smoke regularly. Although our data suggest that former smokers, short-term smokers, and light smokers are at decreased CRC risk, these findings need further confirmation, preferably using prospective designs.

Risks of Lynch syndrome cancers for MSH6 mutation carriers.

Germline mutations in MSH6 account for 10%-20% of Lynch syndrome colorectal cancers caused by hereditary DNA mismatch repair gene mutations. Because there have been only a few studies of mutation carriers, their cancer risks are uncertain. We identified 113 families of MSH6 mutation carriers from five countries that we ascertained through family cancer clinics and population-based cancer registries. Mutation status, sex, age, and histories of cancer, polypectomy, and hysterectomy were sought from 3104 of their relatives. Age-specific cumulative risks for carriers and hazard ratios (HRs) for cancer risks of carriers, compared with those of the general population of the same country, were estimated by use of a modified segregation analysis with appropriate conditioning depending on ascertainment. For MSH6 mutation carriers, the estimated cumulative risks to ages 70 and 80 years, respectively, were as follows: for colorectal cancer, 22% (95% confidence interval [CI] = 14% to 32%) and 44% (95% CI = 28% to 62%) for men and 10% (95% CI = 5% to 17%) and 20% (95% CI = 11% to 35%) for women; for endometrial cancer, 26% (95% CI = 18% to 36%) and 44% (95% CI = 30% to 58%); and for any cancer associated with Lynch syndrome, 24% (95% CI = 16% to 37%) and 47% (95% CI = 32% to 66%) for men and 40% (95% CI = 32% to 52%) and 65% (95% CI = 53% to 78%) for women. Compared with incidence for the general population, MSH6 mutation carriers had an eightfold increased incidence of colorectal cancer (HR = 7.6, 95% CI = 5.4 to 10.8), which was independent of sex and age. Women who were MSH6 mutation carriers had a 26-fold increased incidence of endometrial cancer (HR = 25.5, 95% CI = 16.8 to 38.7) and a sixfold increased incidence of other cancers associated with Lynch syndrome (HR = 6.0, 95% CI = 3.4 to 10.7). We have obtained precise and accurate estimates of both absolute and relative cancer risks for MSH6 mutation carriers.

Smoking and Colorectal Cancer in Lynch Syndrome: Results from the Colon Cancer Family Registry and The University of Texas M.D. Anderson Cancer Center

Smoking and Colorectal Cancer in Lynch Syndrome: Results from the Colon Cancer Family Registry and The University of Texas M.D. Anderson Cancer Center

Current hypotheses on how microsatellite instability leads to enhanced survival of Lynch Syndrome patients.

High levels of microsatellite instability (MSI-high) are a cardinal feature of colorectal tumors from patients with Lynch Syndrome. Other key characteristics of Lynch Syndrome are that these patients experience fewer metastases and have enhanced survival when compared to patients diagnosed with microsatellite stable (MSS) colorectal cancer. Many of the characteristics associated with Lynch Syndrome including enhanced survival are also observed in patients with sporadic MSI-high colorectal cancer. In this review we will present the current state of knowledge regarding the mechanisms that are utilized by the host to control colorectal cancer in Lynch Syndrome and why these same mechanisms fail in MSS colorectal cancers.

Genetic variants in the cell cycle control pathways contribute to early onset colorectal cancer in Lynch syndrome

Lynch syndrome is an autosomal dominant syndrome of familial malignancies resulting from germ line mutations in DNA mismatch repair (MMR) genes. Our goal was to take a pathway-based approach to investigate the influence of polymorphisms in cell cycle-related genes on age of onset for Lynch syndrome using a tree model. We evaluated polymorphisms in a panel of cell cycle-related genes (AURKA, CDKN2A, TP53, E2F2, CCND1, TP73, MDM2, IGF1, and CDKN2B) in 220 MMR gene mutation carriers from 129 families. We applied a novel statistical approach, tree modeling (Classification and Regression Tree), to the analysis of data on patients with Lynch syndrome to identify individuals with a higher probability of developing colorectal cancer at an early age and explore the gene-gene interactions between polymorphisms in cell cycle genes. We found that the subgroup with CDKN2A C580T wild-type genotype, IGF1 CA-repeats >or=19, E2F2 variant genotype, AURKA wild-type genotype, and CCND1 variant genotype had the youngest age of onset, with a 45-year median onset age, while the subgroup with CDKN2A C580T wild-type genotype, IGF1 CA-repeats >or=19, E2F2 wild-type genotype, and AURKA variant genotype had the latest median age of onset, which was 70 years. Furthermore, we found evidence of a possible gene-gene interaction between E2F2 and AURKA genes related to CRC age of onset. Polymorphisms in these cell cycle-related genes work together to modify the age at the onset of CRC in patients with Lynch syndrome. These studies provide an important part of the foundation for development of a model for stratifying age of onset risk among those with Lynch syndrome.