Revised Bethesda Guidelines Research Articles

Abstract 4855: Poor performance of published clinical screening criteria for the population-based identification of endometrial cancer patients with Lynch Syndrome.

Abstract Objective: Clinically based risk assessment tools, targeting those with young age of cancer onset and family history of specific cancers, have been used to identify individuals with Lynch Syndrome (LS). Women with LS are equally likely to develop endometrial carcinoma (EC) as they are colorectal carcinoma (CRC). To identify women presenting with EC at risk for LS, the Society of Gynecologic Oncology (SGO) published recommendations in 2007 regarding which patients would benefit from further genetic evaluation for LS. These criteria are comparable to the Revised Bethesda Guidelines. The primary objective of this study was to evaluate SGO criteria's ability to predict women at risk for LS in the EC population and to ascertain if alternative criteria exist that can better identify high-risk patients. Methods: 408 sequential EC cases were evaluated for immunohistochemical expression of four DNA mismatch repair (MMR) proteins. Tumors with loss of MSH2, MSH6 or PMS2 were designated as probable Lynch Syndrome (PLS). Tumors with loss of MLH1 and absence of MLH1 promoter methylation were also designated PLS. Clinical and pathologic data were collected from the electronic medical record. Results: Of the 408 EC cases, 43 (10.5%) of the patients were defined as probable Lynch Syndrome (PLS). 97/408 (23.7%) of EC cases met SGO criteria, but only 14 of these 97 cases (14.4%) were PLS. Of the 43 PLS cases, 29/43 (67.4%) did not meet SGO criteria. Comparison of clinical and pathologic characteristics, including age of cancer diagnosis and family history of EC and/or CRC, revealed no statistically significant differences between sporadic and PLS tumors with the exception of tumors arising from the lower uterine segment. Tumors with this sight of origin are more likely to be associated with PLS. The sensitivity and specificity of SGO criteria was 32.6% and 77.2%, respectively. Conclusions: Existing clinical guidelines for detecting endometrial carcinoma patients at elevated risk for having Lynch Syndrome perform poorly in an unselected patient population. With the exception of tumors arising from the lower uterine segment, there are no statistically significant clinical or pathological differences between sporadic tumors and PLS tumors. Lower uterine segment EC occurs in only 3% of all EC cases and is not a useful screening tool. SGO clinical criteria correctly identified 32.6% of women with PLS, which results in missed CRC screening opportunities for 67% of women with increased risk profiles. These results suggest that the SGO guidelines are inadequate for identifying LS. Given the lack of effective clinical or pathological screening tools, MMR IHC and MLH1 methylation testing of all endometrial cancer patients may be the best way to identify women at risk for having Lynch Syndrome. Citation Format: Amanda S. Bruegl, Bojana Djordjevic, Bryan M. Fellman, Diana L. Urbauer, Raja Luthra, Karen H. Lu. Poor performance of published clinical screening criteria for the population-based identification of endometrial cancer patients with Lynch Syndrome. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 4855. doi:10.1158/1538-7445.AM2013-4855

Recording of family history is associated with colorectal cancer stage

Colorectal cancer (CRC) associated with Lynch syndrome usually presents at a relatively young age. The Revised Bethesda Guidelines advise screening for Lynch syndrome in patients diagnosed with CRC and a positive family history (FH) of CRC and other Lynch-related cancers. To evaluate recording of the FH and identify factors associated with recording in young patients with CRC. In one academic and two nonacademic hospitals, of all patients diagnosed with CRC at the age of 60 years or younger between 1999 and 2007, electronic medical records were evaluated for a recorded FH of CRC and other Lynch-related cancers. Patient and tumor characteristics were retrieved from the Dutch Comprehensive Cancer Centre and the Dutch Pathological Archive. A total of 676 patients were identified. FH was recorded in 395/676 (58%) patients. From 1999 to 2007, recording improved with an odds ratio (OR) of 1.10 [95% confidence interval (CI) 1.03-1.17] per year. Stage III CRC (OR 1.71, 95% CI 1.07-2.75) and administration of chemotherapy (OR 1.84, 95% CI 1.17-2.89) were associated with recording in multivariate analysis. Other factors, including age at diagnosis, sex, surgery, radiotherapy, proximal tumor localization, poor differentiation, and mucinous histology, were not associated with recording. A FH of CRC and other Lynch-related cancers was not recorded in ∼40% of young CRC patients and recording improved only slightly over the years. As a first step in the identification of Lynch-related cancer families, physicians should be trained to record a detailed FH in the work-up of all newly diagnosed CRC patients.

Improving identification of lynch syndrome patients: A comparison of research data with clinical records

Current evidence suggests poor identification and referral of Lynch syndrome patients. This study evaluated the strategies by which patients with endometrial cancer were referred to genetics services. Data from clinic-based patients with endometrial cancer enrolled through the Australian National Endometrial Cancer population-based research study with detailed family history information were analyzed. The Amsterdam II criteria, the revised Bethesda guidelines, and criteria adapted for this study was assessed using personal/family history information. The percentages of patients referred and who could have been referred to genetics services, and the performance of each criterion for identifying possible mismatch-repair (MMR) gene mutation carriers, based on tumor MMR immunohistochemistry (IHC), were determined. Research data indicated that 236/397(59%) of patients with endometrial cancer had family/personal history of cancer, including 14 (4%) who fulfilled Amsterdam II criteria. Family history information was noted in the hospital records for only 61(15%) patients, including 7/14 (50%) of patients meeting Amsterdam criteria, and always less extensively than that recorded in the research setting. Only 13 patients (two meeting Amsterdam criteria) were referred for genetic assessment. Of 58 patients with tumor MMR protein-IHC loss, the Amsterdam criteria and Bethesda guidelines identified only three and 34% of these possible germline mutation carriers, respectively. Greater sensitivity (60%) was obtained using a single criterion proposed by our study, ≥2 first-degree or second-degree relatives reporting Lynch cancers. Hospital records indicate poor recognition of family history. Application of research methods show improved identification and may facilitate appropriate referrals of endometrial cancer patients with possible Lynch syndrome.

Secondary mutation in a coding mononucleotide tract in MSH6 causes loss of immunoexpression of MSH6 in colorectal carcinomas with MLH1/PMS2 deficiency

Immunohistochemical staining for DNA mismatch repair proteins may be affected by various biological and technical factors. Staining variations that could potentially lead to erroneous interpretations have been recognized. A recently recognized staining variation is the significant reduction of staining for MSH6 in some colorectal carcinomas. The frequency and specific characteristics of this aberrant MSH6 staining pattern, however, have not been well analyzed. In this study of 420 colorectal carcinoma samples obtained from patients fulfilling the Revised Bethesda Guidelines, we detected 9 tumors (2%) showing extremely limited staining for MSH6 with positive staining present in <5% of the tumor cells. Our analyses showed that these tumors belonged to two distinct categories: (1) MLH1 and/or PMS2 protein-deficient carcinomas (n=5, including 1 with a pathogenic mutation in PMS2); and (2) MLH1, PMS2 and MSH2 normal but with chemotherapy or chemoradiation therapy before surgery (n=4). To test our hypothesis that somatic mutation in the coding region microsatellite of the MSH6 gene might be a potential underlying mechanism for such limited MSH6 staining, we evaluated frameshift mutation in a (C)8 tract in exon 5 of the MSH6 gene in seven tumors that had sufficient DNA for analysis, and detected mutation in four; all four tumors belonged to the MLH1/PMS2-deficient group. In conclusion, our data outline the main scenarios where significant reduction of MSH6 staining is more likely to occur in colorectal carcinoma, and suggest that somatic mutations of the coding region microsatellites of the MSH6 gene is an underlying mechanism for this staining phenomenon in MLH1/PMS2-deficient carcinomas.

Abstract A54: Can clinical criteria reliably distinguish between sporadic and Lynch Syndrome-associated endometrial carcinomas with immunohistochemical loss of MLH1?

Abstract Background: Lynch syndrome is a hereditary cancer syndrome caused by a germline defect in one of 4 DNA mismatch repair genes: MLH1, MSH2, MSH6, or PMS2. Hallmark tumors for this syndrome, endometrial and colorectal cancers, have a prevalence of 60-80% in affected individuals. Accurate identification of patients with this syndrome allows for cancer prevention measures to be instituted in the index patient as well as relatives that test positive for the mutation. Referral for genetic testing for Lynch syndrome is often based on clinical screening criteria, which includes young age of cancer diagnosis and a family history of Lynch syndrome associated tumors. Immunohistochemistry and microsatellite instability analysis have emerged as additional screening tools to assist in evaluating a tumor's probability of being sporadic or secondary to Lynch syndrome. This type of testing can either be used universally on all endometrial carcinomas as an initial triage step, or it can be used after clinical screening criteria has identified someone as at-risk. One limitation of using only microsatellite instability testing and immunohistochemistry is that 15-20% of sporadic endometrial and colorectal cancers have immunohistochemical loss of the DNA mismatch repair protein MLH1 and the presence of high levels of microsatellite instability due to methylation of MLH1 rather than germline mutation of MLH1. A follow up test, the PCR-based MLH1 methylation assay, assists in differentiating sporadic endometrial cancers from probable Lynch syndrome tumors in this subset exhibiting immunohistochemical loss of MLH1. A limitation of this assay is that it is PCR-based and may not be accessible to many smaller clinical laboratories. The objective of this study was to determine if Society of Gynecologic Oncology (SGO) clinical criteria were able to correctly distinguish between sporadic endometrial cancers (MLH1 methylated) from probable Lynch syndrome-associated endometrial cancer (MLH1 unmethylated). Methods: Patients with endometrial carcinomas that had undergone hysterectomy at our institution and had immunohistochemical testing for MLH1 and MLH1 promoter methylation analysis were included in this study. Electronic medical records were reviewed to obtain complete clinical and pathologic data for each case. SGO criteria, a modified form of the Revised Bethesda guidelines which uses endometrial cancer as the cancer of reference, were applied to all patients. Results: Of 337 endometrial carcinomas that underwent immunohistochemical evaluation of the four DNA mismatch repair proteins, 54 had immunohistochemical loss of MLH1. 40/54 had MLH1 methylation and were designated as sporadic, while 14/54 lacked MLH1 methylation and were designated as probable Lynch syndrome. In our cohort, 22/54 endometrial carcinoma patients had clinical features that fulfilled SGO criteria for further genetic evaluation, including germline testing for mutation of MLH1. The SGO criteria correctly identified 10/14 probable Lynch syndrome patients. The sensitivity and specificity of SGO criteria within this population were 71.4% and 69.2%, respectively. Conclusions: SGO criteria correctly identified 71% of Lynch syndrome-associated endometrial carcinomas with immunohistochemical loss of MLH1. In addition to missing nearly 30% of endometrial cancer patients with a likely diagnosis of Lynch syndrome, use of SGO criteria alone without the PCR-based MLH1 promoter methylation assay would result in an additional 12 individuals undergoing unindicated germline MLH1 mutational testing. Using the MLH1 methylation assay decreases the number of cases referred for germline testing to 14, thus making the clinical evaluation of these patients more cost effective. Our study highlights the importance of the MLH1 methylation assay in the evaluation of patients undergoing molecular diagnostic testing and evaluation for Lynch syndrome. Citation Format: Amanda S. Bruegl, Bojana Djordjevic, Diana Urbauer, Shannon N. Westin, Pamela T. Soliman, Karen H. Lu, Rajyalakshmi Luthra, Russell R. Broaddus. Can clinical criteria reliably distinguish between sporadic and Lynch syndrome-associated endometrial carcinomas with immunohistochemical loss of MLH1? [abstract]. In: Proceedings of the Eleventh Annual AACR International Conference on Frontiers in Cancer Prevention Research; 2012 Oct 16-19; Anaheim, CA. Philadelphia (PA): AACR; Cancer Prev Res 2012;5(11 Suppl):Abstract nr A54.

ColoSeq Provides Comprehensive Lynch and Polyposis Syndrome Mutational Analysis Using Massively Parallel Sequencing

Lynch syndrome (hereditary nonpolyposis colon cancer) and adenomatous polyposis syndromes frequently have overlapping clinical features. Current approaches for molecular genetic testing are often stepwise, taking a best-candidate gene approach with testing of additional genes if initial results are negative. We report a comprehensive assay called ColoSeq that detects all classes of mutations in Lynch and polyposis syndrome genes using targeted capture and massively parallel next-generation sequencing on the Illumina HiSeq2000 instrument. In blinded specimens and colon cancer cell lines with defined mutations, ColoSeq correctly identified 28/28 (100%) pathogenic mutations in MLH1, MSH2, MSH6, PMS2, EPCAM, APC, and MUTYH, including single nucleotide variants (SNVs), small insertions and deletions, and large copy number variants. There was 100% reproducibility of detection mutation between independent runs. The assay correctly identified 222 of 224 heterozygous SNVs (99.4%) in HapMap samples, demonstrating high sensitivity of calling all variants across each captured gene. Average coverage was greater than 320 reads per base pair when the maximum of 96 index samples with barcodes were pooled. In a specificity study of 19 control patients without cancer from different ethnic backgrounds, we did not find any pathogenic mutations but detected two variants of uncertain significance. ColoSeq offers a powerful, cost-effective means of genetic testing for Lynch and polyposis syndromes that eliminates the need for stepwise testing and multiple follow-up clinical visits.

Tu1193 Lynch Syndrome: Application of the Revised Bethesda Guidelines in Clinical Practice

Aims: The efficacy of endoscopic screening for esophageal cancer (EC) in patients with head and neck cancer (HNC) remains controversial and its impact on the patient prognosis has not been adequately discussed. We have attempted to provide clinical data regarding the usefulness of endoscopic screening for early EC in patient with HNC. Materials and Methods: We retrospectively reviewed a total of 714 HNCs (oral cavity in 236, pharynx in 224, and larynx in 254 patients) which were pathologically confirmed as squamous cell carcinoma. Results: Of the 714 patients, 590 (82.6%) were males; median age was 59.6 years. Thirtysix ECs were detected in 36 (5%) patients (28 synchronous and 8 metachronous). The median interval time between the diagnosis of HNC and EC was 7.78 months (range: 0-72 months). Among the 36 ECs, the early and advanced EC numbered 17 (47.2%) and 18 (52.8%), respectively. The three-year overall survival rates in patients with HNC only and in HNC combined with EC, were 71.2% and 48.2%, respectively (P <0.001). In 36 patients with EC, the three-year overall survival rates with early and advanced EC were 77.7% and 21.7%, respectively (P =0.01). On multivariate analysis, the location of HNC (pharynx) was associated with the development of second primary EC (Odds ratio 3.916, P = 0.018). Conclusions: This study showed a high incidence of EC in HNC patients. In our study patients with HNC, early EC was associated with a good prognosis compared with that seen in advanced EC. Therefore, endoscopic screening to detect early EC in HNC is necessary.

Impact of mismatch repair (MMR) testing on colorectal cancer (CRC) oncology clinical practice.

603 Background: MMR deficiency (dMMR) has been reported in 15% of CRC, but with a lower frequency in advanced disease. Most cases are due to sporadic MLH1 promoter hypermethylation (often with BRAF mutations), with a minority reflecting germline mutations in MLH1, MSH2, PMS2, or MSH6 (Lynch Syndrome [LS]). The Revised Bethesda Guidelines (RBG) are one means of selecting individuals at risk of LS for further assessment, but will miss a proportion of cases. Methods: We screened all consenting patients for eligibility for CRC trials recruiting specific genetic aberrations, which included MMR assessment. Results: Of 314 patients, immunohistochemistry (IHC) for MMR protein expression is complete on 171. Staining was reduced/absent in 19.3% of tests, and heterogeneous in 12.1%. The dMMR rate was 6.4%. 2 dMMR patients* were identified as at risk of LS, and referred to genetics by their treating clinician before IHC results were known. However 4 other cases† were not referred, and an underlying predisposition would have been missed without this unbiased approach. 4 patients developed metastatic disease, with none experiencing a partial response to chemotherapy thus far. (Table.) Conclusions: This data is representative of a practice with a high proportion of metastatic disease. It suggests that within oncology, an unbiased screening approach for LS is preferable. Whilst the RBG detect the majority of cases, they may be underutilised as other management issues take precedence in oncology clinics. A cost-effective alternative may be the introduction of a nurse-led programme to identify cases at risk, as is being introduced at our centre. A spectrum of clinical behavior exists amongst metastatic dMMR CRC, and larger numbers will reveal if this affects therapeutic response. [Table: see text]

Lynch syndrome screening in newly diagnosed colorectal cancer in general pathology practice: From the revised Bethesda guidelines to a universal approach

Objective. Lynch syndrome (LS) is the most common hereditary form of colorectal cancer (CRC). The revised 2004 Bethesda guidelines were developed to identify potential LS patients. This study aimed to retrospectively evaluate utilization and adequacy of the guidelines in general pathology practice and to determine if a universal LS screening approach increased the potential LS detection rate in newly diagnosed CRCs. Material and Methods. Included were 445 primary CRCs surgically resected from November 2006 to March 2009, when reflex microsatellite instability (MSI) testing was based on histomorphology and age as well as 145 CRCs resected from July 2009 to July 2010 when a universal LS testing paradigm was used. Reflex MSI testing rates and MSI testing results were determined. Results. The overall LS screening rate from November 2006 to March 2009 was 34.8%, and the extrapolated microsatellite instability-high (MSI-H) rate was 8.5% (38/445). Strict adherence to the revised Bethesda guidelines, that is, without testing CRC diagnosed in patients ‡60 years, would have missed 26 (68.4%) MSI-H CRCs. The overall LS screening rate from July 2009 to July 2010 was 76.3% and the MSI-H rate was 20.6% (30/145). Compared with the MSI tested group, the untested group had more CRCs removed by local excision (22.2% vs. 4.8%, p = 0.00035). Conclusion. The revised Bethesda guidelines are inadequate for LS screening when personal and family cancer history is not available to the pathologist, a universal screening paradigm greatly increased the rate of MSI testing and MSI-H CRC detection and CRCs less likely to be screened for LS were those diagnosed in locally excised specimens.

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...

Management of young onset colorectal cancer: divergent practice in the East of England

According to the revised Bethesda Guidelines, colorectal cancer (CRC) occurring under age 50 years should be screened to exclude Lynch syndrome. However, in current practice in East Anglia, tumour screening is initiated only after genetics referral, reserved for those with a strong pedigree. This study aimed to determine how many patients with young-onset CRC undergo tumour screening in hospitals in East Anglia. A retrospective case notes review over 5 years in four hospitals was undertaken to determine what proportion of those with young-onset CRC underwent referral for tumour screening and to assess local practices in terms of patient counselling and management. One hundred and twenty-two patients were included. There was an average yearly caseload of 6-9 patients per hospital. Documented family history was rare, as was counselling concerning metachronous and extra-colonic tumour risk and CRC risk in relatives. The rate of referral for genetic testing varied from 44% to 65%. Postoperative colonoscopic surveillance was inconsistent. Many patients with young-onset CRC are managed as sporadic cancers, without Lynch syndrome having been excluded. This may have implications for survival of patients and any affected relatives. A streamlined management algorithm for tumour screening and genetics referral is recommended.

Evaluation of predictive models in daily practice for the identification of patients with Lynch syndrome

The optimal strategy for identifying patients with Lynch syndrome among patients with newly diagnosed colorectal cancer (CRC) is still debated. Several predictive models (e.g., MMRpredict, PREMM1,2 and MMRpro) combining personal and familial data have recently been developed to quantify the risk that a given patient with CRC carries a Lynch syndrome-causing mutation. Their clinical applicability to patients with CRC from the general population requires evaluation. We studied a consecutive series of 214 patients with newly diagnosed CRC characterized for tumor microsatellite instability (MSI), somatic BRAF mutation, MLH1 promoter methylation and mismatch repair (MMR) gene germline mutation status. The performances of the models for identifying MMR mutation carriers (8/214, 3.7%) were evaluated and compared to the revised Bethesda guidelines and a molecular strategy based on MSI testing in all patients followed by the exclusion of MSI-positive sporadic cases from mutational testing by screening for BRAF mutation and MLH1 promoter methylation. The sensitivities of the three models, at the lowest thresholds proposed, were identical (75%), with similar numbers of probands eligible for further MSI testing (almost half the patients). In our dataset, the prediction models gave no better discrimination than the revised Bethesda guidelines. Both approaches failed to identify two of the eight mutation carriers (the same two patients, aged 67 and 81 years, both with no family history). Thus, like the revised Bethesda guidelines, predictive models did not identify all patients with Lynch syndrome in our series of consecutive CRC. Our results support systematic screening for MMR deficiency in all new CRC cases.

Comparison of clinical schemas and morphologic features in predicting Lynch syndrome in mutation‐positive patients with endometrial cancer encountered in the context of familial gastrointestinal cancer registries

Endometrial cancer (EC) is the most common extraintestinal malignancy in Lynch syndrome (LS) and often is the sentinel malignancy, yet there is no consensus regarding LS-EC detection algorithms. In this study, the authors determined the efficacy of family/personal history and tumor morphology in predicting LS in a cohort of patients with EC who had mutation-proven LS. Amsterdam II (AmII) criteria, revised Bethesda guidelines (rBG), and Society of Gynecologic Oncologists (SGO) clinical screening criteria were applied to the pedigrees of 76 patients with mutation-proven LS who had pathology-proven EC. When tumors were tested for microsatellite instability (MSI) phenotype status or mismatch-repair protein-immunohistochemical (MMR-IHC) expression, those results also were reviewed, and LS-associated histopathologic features were documented in 38 available patients. Of 76 patients, 36%, 58%, 71%, and 93% would have been selected for further testing for LS by pedigree screening at the time of EC diagnosis with rBG, AmII, SGO 20%-to-25%, and SGO 5%-to-10% criteria, respectively. Ninety percent (18 of 20 tumors) of tested ECs had high MSI, and 96% (22 of 23 tumors) had abnormal MMR-IHC expression. At least 1 LS-EC morphologic feature was present in 16 of 38 tumors (42%). Clinical screening criteria had variable efficacy for the identification of LS-associated EC, and SGO 5%-to-10% criteria performed best. Characteristic pathologic features were present in a minority of patients. Although a high proportion of LS-ECs had the MSI phenotype and were MMR deficient, the specificity of these tests and of clinical screening for LS in unselected patients with EC has been poorly described. Prospective studies to determine the optimal combination of these screening modalities are required.

Patient and tumor characteristics may raise clinicians' awareness of familial colorectal cancer: A Norwegian population-based study

Background. The aim of this study was to identify patient and tumor characteristics that may be useful for clinicians in the identification of possible familial colorectal cancer (CRC). Methods. Among 562 unselected, consecutively diagnosed colorectal cancer patients, 490 patients were included and divided into familial or sporadic CRC based on family history data collected by standardized patient interviews. Clinical data were collected from the patients' medical records. Patients were classified as familial CRC according to currently accepted family history criteria. Each patient was also classified according to Amsterdam II criteria and the 4th and 5th criteria in the Revised Bethesda Guidelines that address information on family history. Tumors were described by location and histopathology; 316 tumors were examined by molecular analyses. Results. Right-sided colonic tumors and synchronous CRC tumors were associated with familial CRC, and patients with metachronous CRC or Lynch syndrome-related tumors were more likely to be classified as familial CRC. The patients' age at diagnosis did not differ between the groups. Other patient or tumor characteristics were not associated with familial CRC. Conclusion. CRC patients with right-sided colonic cancers, synchronous cancers and previous CRC and/or LS-related tumors were more likely to have familial CRC, and young age at diagnosis was not associated with familial CRC in these data. A detailed family history of colorectal cancer is essential in the identification of patients and families with familial CRC.

Revised Bethesda Guidelines: compliance in identifying HNPCC affected families

IntroductionHereditary non-polyposis colorectal cancer (HNPCC) causes approximately 3% of colorectal cancer cases in the UK and has significant implications for screening families with multiple affected members. It is usually caused...

Clinicopathologic and genetic features of Chinese hereditary nonpolyposis colorectal cancer (HNPCC).

382 Background: Hereditary non-polyposis colorectal cancer (HNPCC) is the most common hereditary colorectal cancer (CRC). At least five mismatch repair genes, majorly hMLH1and hMSH2 gene mutations, are associated with this syndrome. Given the geographical and racial differences, Chinese HNPCC patients have some special characteristics compared with patients in West countries. Based on our former studies, we developed a criteria, the Fudan Criteria, for clinical diagnosis of Chinese HNPCC. The aim of this study is (1) to understand the relationship between genotype and phenotype in Chinese HNPCC; and (2) to investigate the clinical value of Fudan Criteria. Methods: 116 unrelated probands of HNPCC or suspected HNPCC families from the Fudan Colorectal Registry were studied. 32 families fulfilled the Amsterdam criteria (AC group), 28 families fulfilled the Fudan Criteria (FD group). 56 families met the revised Bethesda guideline (BG Group). Direct DNA sequencing of all exons of hMSH2 and hMLH1 genes were performed. Mutation and clinicalpathological features were compared between the groups. Results: 32 pathological germline mutations were identified. 16/32 mutations were located at hMLH1 and 16/32 located at hMSH2. The sensitivity of Amsterdam Criteria was 50%, specificity was 81% and Youden's index was 31%. The sensitivity of Fudan Criteria was 75%, specificity was 58% and Youden's index was 33%. In AC group, there were no significant clinicopathological differences in patients with or without mutation. However, families with hMSH2 mutation had a higher ratio of synchronous and metachronous CRC than families with hMLH1 mutation (33% vs. 6%; P=0.04). Families in AC group share the same clinicopathological features with families in FD group, except multiple relative tumors (21.6% vs.6%; P=0.001). Conclusions: There seems no close relation between genotype and phenotype, except patients with hMSH2 mutation more frequently harbor synchronous and metachronous CRC. Fudan Criteria had a little higher sensitivity and accuracy than Amsterdam Criteria for identification of Chinese HNPCC. No significant financial relationships to disclose.

Evidence for classification of c.1852_1853AA&gt;GC in MLH1 as a neutral variant for Lynch syndrome

BackgroundLynch syndrome (LS) is an autosomal dominant inherited cancer syndrome characterized by early onset cancers of the colorectum, endometrium and other tumours. A significant proportion of DNA variants in LS patients are unclassified. Reports on the pathogenicity of the c.1852_1853AA>GC (p.Lys618Ala) variant of the MLH1 gene are conflicting. In this study, we provide new evidence indicating that this variant has no significant implications for LS.MethodsThe following approach was used to assess the clinical significance of the p.Lys618Ala variant: frequency in a control population, case-control comparison, co-occurrence of the p.Lys618Ala variant with a pathogenic mutation, co-segregation with the disease and microsatellite instability in tumours from carriers of the variant. We genotyped p.Lys618Ala in 1034 individuals (373 sporadic colorectal cancer [CRC] patients, 250 index subjects from families suspected of having LS [revised Bethesda guidelines] and 411 controls). Three well-characterized LS families that fulfilled the Amsterdam II Criteria and consisted of members with the p.Lys618Ala variant were included to assess co-occurrence and co-segregation. A subset of colorectal tumour DNA samples from 17 patients carrying the p.Lys618Ala variant was screened for microsatellite instability using five mononucleotide markers.ResultsTwenty-seven individuals were heterozygous for the p.Lys618Ala variant; nine had sporadic CRC (2.41%), seven were suspected of having hereditary CRC (2.8%) and 11 were controls (2.68%). There were no significant associations in the case-control and case-case studies. The p.Lys618Ala variant was co-existent with pathogenic mutations in two unrelated LS families. In one family, the allele distribution of the pathogenic and unclassified variant was in trans, in the other family the pathogenic variant was detected in the MSH6 gene and only the deleterious variant co-segregated with the disease in both families. Only two positive cases of microsatellite instability (2/17, 11.8%) were detected in tumours from p.Lys618Ala carriers, indicating that this variant does not play a role in functional inactivation of MLH1 in CRC patients.ConclusionsThe p.Lys618Ala variant should be considered a neutral variant for LS. These findings have implications for the clinical management of CRC probands and their relatives.

Incidence and histological features of colorectal cancer in the Northern Cape Province, South Africa.

The purpose of this study was to determine the incidence of colorectal cancer (CRC) in the Northern Cape province of South Africa, and to identify patients with histological and demographic features suggestive of hereditary non-polyposis colon cancer (HNPCC). This is a retrospective review of all cases of primary adenocarcinoma of the colon or rectum diagnosed by the two pathology laboratories operating in the Northern Cape between January 2002 and February 2009. Demographic data were collected, as well as pathological staging of the tumours and histological features suggestive of HNPCC (according to the revised Bethesda guidelines for microsatellite instability testing). Population census data for the Northern Cape were obtained from Statistics South Africa. The annual incidence of CRC in the Northern Cape was 3.7/100,000 population (3.5/100,000 for men and 3.9/100,000 for women). The median age at which colorectal cancer was diagnosed was 59 years (range 16-90 years). On pathological and demographic criteria, 75/206 (36%) of the patients met at least one of the criteria of the revised Bethesda guidelines for microsatellite instability testing. CRC is rare in the Northern Cape, and one-third of the patients had demographic or tumour histological features suggestive of HNPCC.

A Histology-Based Model for Predicting Microsatellite Instability in Colorectal Cancers

Identifying colorectal cancers (CRCs) with high levels of microsatellite instability (MSI-H) is clinically important. MSI-H is a positive prognostic marker for CRC, a predictive marker for resistance to standard 5-fluorouracil-based adjuvant chemotherapy, and an important feature for identifying individuals and families with Lynch syndrome. Our aim was to compare and improve upon the existing predictive pathology models for MSI-H CRCs. We tested 2 existing models used to predict MSI-H tumors, (1) Revised Bethesda Guidelines and (2) MsPath, in our population-based cohort of CRCs diagnosed less than 75 years from Newfoundland (N=710). We also scored additional histologic features not described in the other models. From this analysis, we developed a model for the prediction of MSI-H CRCs; Pathologic Role in Determination of Instability in Colorectal Tumors (PREDICT). An independent pathologist validated this model in a second cohort of all CRCs (N=276). Tumor histology was a better predictor of MSI status than was personal and family history of cancer. MsPath identified MSI-H CRCs with a sensitivity of 92.1% and a specificity of 37.8%, whereas the Revised Bethesda Guidelines had a sensitivity of 81.3% and a specificity of 39.5%. PREDICT included some new histology features, including peritumoral lymphocytic reaction and increased proportion of plasma cells in the tumor stroma. PREDICT was superior to both existing models in the development cohort with a sensitivity of 97.4% and a specificity of 53.9%. In the validation cohort, sensitivity was 96.9% and specificity 76.6%. We conclude that PREDICT is a good predictor of MSI-H CRC.

The revised Bethesda guidelines: extent of utilization in a university hospital medical center with a cancer genetics program.

BackgroundIn 1996, the National Cancer Institute hosted an international workshop to develop criteria to identify patients with colorectal cancer who should be offered microsatellite instability (MSI) testing due to an increased risk for Hereditary Nonpolyposis Colorectal Cancer (HNPCC). These criteria were further modified in 2004 and became known as the revised Bethesda Guidelines. Our study aimed to retrospectively evaluate the percentage of patients diagnosed with HNPCC tumors in 2004 who met revised Bethesda criteria for MSI testing, who were referred for genetic counseling within our institution.MethodsAll HNPCC tumors diagnosed in 2004 were identified by accessing CoPath, an internal database. Both the Tumor Registry and patients' electronic medical records were accessed to collect all relevant family history information. The list of patients who met at least one of the revised Bethesda criteria, who were candidates for MSI testing, was then cross-referenced with the database of patients referred for genetic counseling within our institution.ResultsA total of 380 HNPCC-associated tumors were diagnosed at our institution during 2004 of which 41 (10.7%) met at least one of the revised Bethesda criteria. Eight (19.5%) of these patients were referred for cancer genetic counseling of which 2 (25%) were seen by a genetics professional. Ultimately, only 4.9% of patients eligible for MSI testing in 2004 were seen for genetic counseling.ConclusionThis retrospective study identified a number of barriers, both internal and external, which hindered the identification of individuals with HNPCC, thus limiting the ability to appropriately manage these high risk families.