Hereditary Nonpolyposis Colorectal Carcinoma Research Articles

Genomic instability and the selection of treatments for cancer

A critical link exists between DNA mutation and chromosomal rearrangements (genomic instability) and cancer development. This genomic instability can manifest itself as small changes at the nucleotide level or as gross chromosomal alterations. Mutations in the genes that encode DNA damage response proteins are responsible for a variety of genomic instability syndromes including hereditary non-polyposis colorectal carcinoma, Bloom's syndrome, ataxia-telangiectasia, BRCA-associated breast and ovarian cancers and Fanconi anaemia. Similarly, epigenetic silencing of genes associated with the maintenance of genomic stability have also been implicated in the pathogenesis of cancer. Here, we discuss how different tumours may be classified not only by tumour site but also by the type of underlying genetic instability. This type of classification may assist in the optimization of existing treatment regimens as well as informing the development of new therapeutic approaches.

Prognostic relevance of MLH1 and MSH2 mutations in hereditary non-polyposis colorectal cancer patients.

Colorectal carcinoma patients from hereditary non-polyposis colorectal cancer families are suggested to have a better prognosis than sporadic colorectal carcinoma cases. Since the majority of hereditary non-polyposis colorectal cancer-related colorectal carcinomas are characterized by microsatellite instability due to germline mutations in DNA mismatch repair genes, this is consistent with the prolonged survival observed in sporadic microsatellite instability-positive colorectal carcinoma compared to microsatellite stable cases. However, a fraction of colorectal carcinoma cases belongs to families that, despite fulfilling the clinical criteria for hereditary non-polyposis colorectal cancer, do not carry mismatch repair gene mutations. Our aim was to verify to what extent the genotypic heterogeneity influences the prognosis of hereditary non-polyposis colorectal cancer patients. A survival analysis was performed on 526 colorectal carcinoma cases from 204 Amsterdam Criteria-positive hereditary non-polyposis colorectal cancer families. Enrolled cases were classified as MLH1-positive, MSH2-positive and mutation-negative, according to the results of genetic testing in each family. Five-year survival rates were 0.73 (95% CI, 0.66-0.80), 0.75 (95% CI, 0.66-0.84) and 0.62 (95% CI, 0.55-0.68) for MLH1-positive, MSH2-positive and mutation-negative groups, respectively (logrank test, P = 0.01). Hazard ratio, computed using Cox regression analysis and adjusted for age, sex, tumor site and stage, was 0.71 (95% CI, 0.51-0.98) for the mutation-positive compared to the mutation-negative group. Moreover, in the latter group, patients with microsatellite instability-positive colorectal carcinomas showed a better outcome than microsatellite stable cases (5-year survival rates, 0.81 and 0.60, respectively; logrank test, P = 0.006). Our results suggest that the prognosis of hereditary non-polyposis colorectal cancer-related colorectal carcinoma patients depends on the associated constitutional mismatch repair genotype.

Prognostic Relevance of MLH1 and MSH2 Mutations in Hereditary Non-Polyposis Colorectal Cancer Patients

Colorectal carcinoma patients from hereditary non-polyposis colorectal cancer families are suggested to have a better prognosis than sporadic colorectal carcinoma cases. Since the majority of hereditary non-polyposis colorectal cancer-related colorectal carcinomas are characterized by microsatellite instability due to germline mutations in DNA mismatch repair genes, this is consistent with the prolonged survival observed in sporadic microsatellite instability-positive colorectal carcinoma compared to microsatellite stable cases. However, a fraction of colorectal carcinoma cases belongs to families that, despite fulfilling the clinical criteria for hereditary non-polyposis colorectal cancer, do not carry mismatch repair gene mutations. Our aim was to verify to what extent the genotypic heterogeneity influences the prognosis of hereditary non-polyposis colorectal cancer patients. A survival analysis was performed on 526 colorectal carcinoma cases from 204 Amsterdam Criteria-positive hereditary non-polyposis colorectal cancer families. Enrolled cases were classified as MLH1-positive, MSH2-positive and mutation-negative, according to the results of genetic testing in each family. Five-year survival rates were 0.73 (95% CI, 0.66-0.80), 0.75 (95% CI, 0.66-0.84) and 0.62 (95% CI, 0.55-0.68) for MLH1-positive, MSH2-positive and mutation-negative groups, respectively (logrank test, P = 0.01). Hazard ratio, computed using Cox regression analysis and adjusted for age, sex, tumor site and stage, was 0.71 (95% CI, 0.51-0.98) for the mutation-positive compared to the mutation-negative group. Moreover, in the latter group, patients with microsatellite instability-positive colorectal carcinomas showed a better outcome than microsatellite stable cases (5-year survival rates, 0.81 and 0.60, respectively; logrank test, P = 0.006). Our results suggest that the prognosis of hereditary non-polyposis colorectal cancer-related colorectal carcinoma patients depends on the associated constitutional mismatch repair genotype.

Molecular Analysis of Endometrial Tumorigenesis: Importance of Complex Hyperplasia Regardless of Atypia

Endometrial carcinoma (EC) is common in the population and the most frequent extracolonic malignancy in hereditary nonpolyposis colorectal carcinoma (HNPCC)/Lynch syndrome. We characterized precursor lesions of endometrioid EC to identify markers of malignant transformation and tumor progression. Serial specimens of normal endometrium, simple hyperplasia, complex hyperplasia without atypia, complex hyperplasia with atypia, and endometrial carcinoma obtained during a 10-year surveillance of DNA mismatch repair (MMR) gene mutation carriers (together 110 samples) were molecularly profiled and compared with a sporadic reference series of endometrial specimens taken for nonmalignant reasons (62 samples). Among MMR gene mutation carriers, decreased MMR protein expression was present in 7% in normal endometrium, 40% in simple hyperplasia, 100% in complex hyperplasia without atypia, 92% in complex hyperplasia with atypia, and 100% in endometrial carcinoma. Microsatellite instability frequencies were lower (6%, 17%, 67%, 38%, and 64%, respectively). Among 24 tumor suppressor genes, the number of methylated loci increased from normal endometrium to simple hyperplasia to complex hyperplasia (complex hyperplasia without atypia/complex hyperplasia with atypia) in both Lynch syndrome and reference series. The most frequently methylated genes were CDH13, RASSF1A, and GSTP1. In MMR gene mutation carriers, MMR and methylation defects appeared up to 12 years before endometrial carcinoma. Molecular changes in endometrial tissue are detectable several years before endometrial carcinoma in genetically predisposed individuals. Abnormal MMR and methylation classify normal endometrium and simple hyperplasia into one category and complex hyperplasia without atypia, complex hyperplasia with atypia, and endometrial carcinoma into another, suggesting that, contrary to a traditional view, complex hyperplasia without atypia and complex hyperplasia with atypia are equally important as precursor lesions of endometrial carcinoma.

Improvement of endometrial biopsy over transvaginal ultrasound alone for endometrial surveillance in women with Lynch syndrome

In women with hereditary non polyposis colorectal carcinoma (HNPCC) an annual gynaecological surveillance has been recommended because of an increased lifetime risk of developing endometrial and ovarian carcinoma. The aim of this study was to assess the efficacy of gynaecological surveillance with regard to endometrial and ovarian carcinoma. Included were women from families that fulfilled the revised Amsterdam criteria for HNPCC or who showed a proven mutation in one of the mismatch repair genes. An annual gynaecological surveillance was performed (transvaginal ultrasound (TVU) and CA 125 assessment). From January 2006 on, routine endometrial sampling was included. In a total number of 100 women 285 surveillance visits were performed. Among these, in 64 visits routine endometrial samplings were performed: three atypical hyperplasias and one endometrial carcinoma were diagnosed. This was significantly more than the atypical hyperplasia and two endometrial carcinomas that were detected after 28 samples performed because of abnormal surveillance results in 221 visits. There were no interval carcinomas. One invasive ovarian carcinoma stage IIIC was diagnosed at ovarian surveillance. Endometrial surveillance with routine endometrial sampling in women with HNPCC is more efficient in diagnosing endometrial (pre)malignancies than TVU only. Ovarian surveillance is not capable of diagnosing early stage ovarian carcinoma. Prophylactic hysterectomy in HNPCC should be restricted to women in whom abdominal surgery for other reasons is performed and to those with particularly increased risk such as MSH6 mutation carriers and/or women with multiple relatives with endometrial carcinoma.

A new mutation in Muir-Torre syndrome associated with familiar transmission of different gastrointestinal adenocarcinomas

Hereditary Nonpolyposis Colorectal Carcinoma (HNPCC) is the most frequent inherited disease which can lead to the development of tumors in the colon and other locations. Its genetic basis is related to the germline mutation of the Mismatch Repair (MMR) genes. Muir-Torre syndrome is considered one of the subtypes of this disease, in which the HNPCC tumor spectrum is frequently associated with sebaceous carcinoma of the skin or keratoacanthoma. A 57 years old male patient is presented with a mucinous carcinoma of the caecum and an adenocarcinoma of the pancreas head. A malignant sebaceous carcinoma was removed from his left neck area. His family history was significant for two cases of colon carcinoma, two cases of stomach cancer and a case of metacron endometrial and skin tumor as well. Both the colon carcinoma and the skin tumor proved to be microsatellite unstable. An Arg>Pro switch missense mutation was found in codon 265 of the hMLH1 gene. This error was found in 4 other members of his family. The detected genetic alteration was considered pathogenic and was not published yet in English literature. The significance of this particular case is the rare tumor association in a patient with Muir-Torre syndrome (MTS). In cases of sebaceous skin lesions, evaluation of family history is of utmost importance in the early detection of HNPCC and in the follow up care of family members with the particular mutation.

The 21st century hepatologist and a systems biology based approach to liver diseases

It is striking how often it is that a 30- to 50-year-old patient will walk into my office with a seemingly mild yet enigmatic problem such as an abnormal aminotransferase level or epigastric pain that persists despite thorough investigation and treatment from their internist. These patients invariably have complicated family histories of multiple cancers or chronic diseases such as diabetes, rheumatoid arthritis, Alzheimer’s disease, and others. Recently, I began linking some of these clinical findings to potentially dysfunctional genetic pathways to effect a diagnosis, treatment, and management plan, and possibly avert disease escalation. Take one recent example of a patient who presented with abnormal aminotransferases and gastric fundic gland polyps (not on proton pump inhibitors). I noted her family history of hepatocellular carcinoma (HCC) and gastric cancer spanning three generations. Familial adenomatous polyposis coli/Gardner’s syndrome with dysfunctional wnt signaling, epigenetic loss of E-cadherin, and silencing of transforming growth factor β signaling are some of the possibilities.1–3 With the right information at hand, this patient’s management plan could include: a screening strategy for HCC and gastric cancer; identifying mutations in affected family members; examining affected gastric tissue for loss of E-cadherin; instituting simple preventive/disease modifying measures such as vitamin D, calcium, and aspirin that switch off pro-oncogenic activated wnt signaling.4,5 Clearly, many patients will need to be studied carefully with genetic networks and a systems biology approach to identify key modifying factors that will effectively work on an individual basis.6 I have most definitely embarked on a steep learning curve as I continue to manage my patients. Possibly, as in hereditary non-polyposis colorectal carcinoma (HNPCC) studies, this patient and her family will eventually fall into a specific genetic group, and we will be able to look to future prevention of other cancers, such as the uterine cancers by earlier hysterectomies in HNPCC patients.7

Microsatellite Instability and Mismatch Repair Protein Defects in Ovarian Epithelial Neoplasms in Patients 50 Years of Age and Younger

Ovarian malignancies occurring in the setting of hereditary nonpolyposis colorectal carcinoma syndrome typically present in young women, often as the first or "sentinel" cancer, but the frequency of microsatellite instability (MSI) and mismatch repair (MMR) defects in ovarian surface epithelial malignancies in women <or=50 years of age is neither well known nor well tested. Fifty-two ovarian surface epithelial carcinomas, including 4 with synchronous endometrial carcinomas, were identified in patients 50 years of age or younger and evaluated for evidence of MSI and MMR protein deficiency. Each case was tested for MSI by multiplex polymerase chain reaction amplification of the National Cancer Institute reference panel (BAT25, BAT26, D2S123, D5S346, and D17S250) and deficiency of MMR protein expression by immunohistochemistry (MLH1, MSH2, MSH6, and PMS2). MMR protein expression and MSI (in a subset of cases) were also evaluated in 50 unselected ovarian serous tumors of low malignant potential , a tumor common in younger women. Defects in MMR were detected in 5 of 52 (10%) ovarian carcinomas by at least 1 testing method, including 2 of 4 (50%) ovarian cancers presenting with synchronous endometrial cancer. Three of the 5 (60%) ovarian carcinomas were clear cell carcinomas (17% of all pure clear cell carcinomas) and the remaining 2 were high-grade carcinomas with endometrioid and mixed histology. Loss of MSH2 and MSH6 was detected in all of the affected clear cell carcinomas and a synchronous endometrial cancer with endometrioid histology. Loss of 1 or more MMR proteins was initially noted in 10/50 ovarian serous tumors of low malignant potential on tissue microarray, but further testing on full tissue sections showed intact protein expression and microsatellite stability in all informative cases. This study demonstrates a 10% rate of MMR-deficient ovarian cancer in women <or=50 years of age. MMR-deficient ovarian cancer is frequently associated with loss of expression of MSH2 and MSH6 proteins and clear cell histology. The occurrence of MMR inactivation in a significant proportion of ovarian clear cell carcinomas (17% in this study) suggests that this tumor may warrant targeted testing in women <or=50 years of age.

Epigenetic Signatures of Familial Cancer Are Characteristic of Tumor Type and Family Category

Tumor suppressor genes (TSG) may be inactivated by methylation of critical CpG sites in their promoter regions, providing targets for early detection and prevention. Although sporadic cancers, especially colorectal carcinoma (CRC), have been characterized for epigenetic changes extensively, such information in familial/hereditary cancer is limited. We studied 108 CRCs and 63 endometrial carcinomas (EC) occurring as part of hereditary nonpolyposis CRC, as separate familial site-specific entities or sporadically, for promoter methylation of 24 TSGs. Eleven genes in CRC and 6 in EC were methylated in at least 15% of tumors and together accounted for 89% and 82% of promoter methylation events in CRC and EC, respectively. Some genes (e.g., CDH13, APC, GSTP1, and TIMP3) showed frequent methylation in both cancers, whereas promoter methylation of ESR1, CHFR, and RARB was typical of CRC and that of RASSF1(A) characterized EC. Among CRCs, sets of genes with methylation characteristic of familial versus sporadic tumors appeared. A TSG methylator phenotype (methylation of at least 5 of 24 genes) occurred in 37% of CRC and 18% of EC (P = 0.013), and the presence versus absence of MLH1 methylation divided the tumors into high versus low methylation groups. In conclusion, inactivation of TSGs by promoter methylation followed patterns characteristic of tumor type (CRC versus EC) and family category and was strongly influenced by MLH1 promoter methylation status in all categories. Paired normal tissues or blood displayed negligible methylation arguing against a constitutional methylation abnormality in familial cases.

Differential cancer predisposition in Lynch syndrome: insights from molecular analysis of brain and urinary tract tumors

Hereditary non-polyposis colorectal carcinoma (Lynch syndrome) is among the most common hereditary cancers in man and a model of cancers arising through deficient DNA mismatch repair (MMR). Lynch syndrome patients are predisposed to different cancers in a non-random fashion, the basis of which is poorly understood. We addressed this issue by determining the molecular profiles for different tumors from a nationwide cohort of Lynch syndrome families (approximately 150 tumors in total). We focused on some less prevalent cancers, affecting the brain (n = 7) and urinary tract (five bladder and five ureter uroepithelial cancers and four kidney adenocarcinomas), and compared their molecular characteristics to those of the most common cancers, colorectal, gastric and endometrial adenocarcinomas, from the same families. Despite origin from verified MMR gene mutation carriers, the frequency of high-level microsatellite instability in tumors varied between high (100-96% for ureter, stomach and colon), intermediate (63-60% for endometrium and bladder) and low (25-0% for kidney and brain). In contrast to gastrointestinal and endometrial carcinomas, active (nuclear) beta-catenin was rare and KRAS mutations were absent in brain and urological tumors. Compared with other tumors, frequent stabilization of p53 protein characterized urinary tract cancers. Promoter methylation of tumor suppressor genes discriminated the tumors in an organ-specific manner. Our findings suggest that different Lynch syndrome tumors develop along different routes. Uroepithelial cancers of the ureter (and bladder to lesser extent) share many characteristics of MMR deficiency-driven tumorigenesis, whereas brain tumors and kidney adenocarcinomas follow separate pathways.

Clinicopathological characteristics in hereditary nonpolyposis colorectal carcinoma-associated endometrial carcinoma

To study clinicopathological characteristics of hereditary nonpolyposis colorectal carcinoma (HNPCC)-associated endometrial carcinoma (EC). Totally 421 EC patients admitted to General Hospital of Tianjin Medical University from 1981 to 2006 were divided into three groups: group A: sporadic EC; group B: familial aggregation of EC; group C: HNPCC-associated EC. HNPCC-associated EC accounted for 6.4% (27/421). Mean age at time of diagnosis was 49.7 years in group C, earlier than 56.3 years in group A (P = 0.004) and 55.2 years in group B (P = 0.035). There were 33.3% (9/27) patients with multiple primary carcinomas in group C. It was higher than 14.3% (9/63) in group B and 5.1% (17/331) in group A respectively (P = 0.038, P < 0.01). There was no difference among the three groups in histological type or menopausal status (P > 0.05). The numbers of patients with low grade EC in group C (70.4%, 19/27) and group B (61.35, 38/62) were more than that in Group A (P = 0.013, P = 0.023). Prognosis for group C was better than that in group A (P = 0.021), and 5- and 10-year survival rate in groups A, B and C was 80%, 70%; 88%, 85%; and 96%, 96% respectively. Mean age at time of diagnosis is earlier in HNPCC-associated EC than that in sporadic EC; patients with HNPCC-associated EC are more frequently complicated with multiple primary carcinomas and of low grade; prognosis is better.

Screening and surveillance for hereditary polyposis and non-polyposis syndromes with capsule endoscopy

The hereditary polyposis syndromes and non-polyposis colorectal carcinoma have been considered as scarcely occurring but inheritable dominant autosomal syndromes. The increasing risk of small bowel carcinoma and prevention of obstruction and intussusception have been making frequent and acute surgical interventions unavoidably led to the necessity of screening and surveillance the patients. Earlier the diagnosis of these symptoms was difficult to establish because traditional radiological methods have a low yield for small polyps. Furthermore, small bowel is only partially accessible with traditional endoscopic techniques such as upper endoscopy, colonoscopy and push-enteroscopy. The "wireless" capsule endoscopy has opened the way then for the non-invasive and painless test of the entire small intestine. - Test results have been cumulated to justify the efficiency and safety of capsule endoscopy concerning the syndromes above. This method can be applied safely even consequently to repeatedly performed surgical interventions by low risk of capsule retention. As the results compared of the diagnosed familial adenomatous polyposis and of Peutz-Jeghers syndrome reflect on capsule endoscopy, its diagnostic sensitiveness is stated as significantly higher than the Barium-contrast X-Ray and MR-enterography. Nevertheless, determination of size and location of polyps has become more problematic when evaluating the test results.

Difficulties in recognizing families with Hereditary Non-polyposis Colorectal Carcinoma. Presentation of 4 families with proven mutation

Introduction Hereditary Non-polyposis Colorectal Carcinoma is the most frequent genetic disease leading to colon and other malignancies. Recognizing the condition requires extensive family history going back several generations focusing particularly on the types of tumors occurring in the family at different age groups. Methods In families who met the Amsterdam and Bethesda Criteria, the removed tumor tissue was first examined by immunohistochemistry and microsatellite instability analysis. Subsequently DNA sequencing was performed to detect an underlying Mismatch Repair Gene mutation and multiple ligation dependent probe amplification was applied for recognizing large deletions in Mismatch Repair Genes. Results In the investigated families 3 pathogen mutations, 1 large deletion and 2 cases of polymorphism were found. There is considerable difference between the families in terms of the types of malignancies and the age in which those appeared. Conclusion Recognizing families with Hereditary Non-polyposis Colorectal Carcinoma presents great difficulties because of the variety of phenotypes in presentation. Special attention should be paid to small families and those who present with cancer of other than colon origin. Practicing physicians should be made aware of the fact that this disease may have atypical presentations. Follow up of families who have already been screened may be difficult for social, economical or religious reasons.

A Prospective, Multicenter, Population-Based Study of BRAF Mutational Analysis for Lynch Syndrome Screening

Mismatch repair (MMR) deficiencies are the hallmark of tumors arising in Lynch syndrome, however, in approximately 15% of sporadic colorectal cancers (CRC) these deficiencies most often are associated with somatic methylation of the MMR gene MLH1. Recently, an oncogenic mutation in the BRAF gene has been involved in sporadic CRC showing MMR deficiencies as a result of MLH1 promoter methylation. The aim of this study was to evaluate the contribution of BRAF V600E mutation analysis in the identification of MSH2/MLH1 gene mutation carriers in newly diagnosed CRC patients. BRAF V600E mutation was analyzed in CRC patients with MMR deficiencies (microsatellite instability and/or lack of MLH1/MSH2 protein expression) in the EPICOLON population-based study. The effectiveness and efficiency of different strategies were evaluated with respect to the presence of MSH2/MLH1 germline mutations. MMR deficiencies were detected in 119 of the 1222 CRC patients with tumors showing either microsatellite instability (n = 111) or loss of protein expression (n = 81). BRAF mutation was detected in 22 (18.5%) of the patients. None of the patients with unambiguous germline mutation had BRAF mutation. Regardless of the strategy used to identify MSH2/MLH1 gene carriers, the introduction of BRAF analysis in these patients slightly improves their effectiveness. The introduction of BRAF mutation analysis as a step before germline genetic testing in patients with MMR deficiencies achieved a significant reduction in costs per mutation detected. Detection of BRAF V600E mutation could simplify and improve the cost effectiveness of genetic testing for hereditary nonpolyposis colorectal cancer, especially in patients whose family history is incomplete or unknown.

Mobile colonoscopic surveillance provides quality care for hereditary nonpolyposis colorectal carcinoma families in South Africa

It is difficult to provide a colonoscopic surveillance service for at-risk family members with hereditary nonpolyposis colorectal carcinoma when many of those family members live in a remote area of South African far from endoscopic services. A mobile surveillance programme was established to service these individuals. The aim of this study was to compare the quality of the mobile service to that provided in established endoscopy units. Ninety-one asymptomatic subjects with known disease-causing mutations underwent 259 colonoscopies. Of these, 171 colonoscopies were performed by a mobile colonoscopy service in small rural hospitals and 88 in established endoscopy units. The quality of the colonoscopic services was measured by completion rate, the rate of detection of colonoscopic abnormalities, histopathological analyses of biopsies, surgical intervention and colorectal cancer deaths. The caecum was reached in 96% of all colonoscopies. A significant lesion was detected in 8.8% of colonoscopies. There was no difference in the rate of complete colonoscopy and detection rate of lesions in the established units and the mobile service (both P = 0.6). The rate of detection of early adenocarcinomas was similar (P = 0.17). The colonoscopic screening/surveillance programme meets international standards with a high accuracy (95.75%) and negative predictive value (100%). The mobile service provides access to colonoscopy in remote areas without compromising the quality of service.

Microsatellite instability in Ewing tumor is not associated with loss of mismatch repair protein expression

Only few clinical factors predict the prognosis of patients with Ewing tumors. Unfavorable outcome is associated with primary metastatic disease, age > 15 years, tumor volume above 200 ml, and the histological response to chemotherapy. The aim of this study was to elucidate the prevalence and clinical impact of microsatellite instability (MSI) together with the relation between MSI and mismatch repair protein expression in Ewing tumors. DNA from 61 primary Ewing tumors and 11 Ewing tumor cell lines was extracted and microsatellite analysis for the detection of instability or loss of heterozygosity was performed for the five markers of the Bethesda panel BAT25, BAT26, D5S346, D2S123, and D17S250, which represents the established marker panel for the analysis of hereditary non-polyposis colorectal carcinoma (HNPCC) patients. In addition, single nucleotide repeat regions of the two tumor genes BAX and transforming growth factor receptor II (TGFBR2) were also included. All of the 61 samples were suitable for LOH analysis and 55 for the determination of MSI-status. LOH of these microsatellite markers was detected in 9 of the 61 patients (14.8%). Over all, genetic instability, i.e. MSI and/or LOH, was detected in 17 tumors (27.9%). One out of the 11 tumor cell lines (STA ET1) was characterized by instability of all the five Bethesda markers, while from primary tumor samples, only one showed MSI in more than one microsatellite marker (D5S346 and D17S250, MSI-high). Eight of the fifty-five patients (14.5%) showed instability of one microsatellite locus (MSI-low). No instability was detected in BAT26, D2S123, BAX and TGFBR2. There was no significant correlation between MSI and loss of expression of mismatch repair proteins MLH1, MSH2, or MSH6. The impairment of the p53 signaling pathway (expression of TP53 and/or MDM2 by immunohistochemistry) was significantly associated with reduced overall survival (15 of 49 patients (30.6%), P = 0.0410, log-rank test). We conclude that MSI is not prevalent in Ewing tumor and that the nature of instability differs from the form observed in colorectal carcinoma, the model tumor of MSI. This is documented by the different pattern of MSI (no BAT26 instability) in Ewing tumors and the lack of a strict correlation between MSI-high and loss of expression of MSH2, MSH6 and MLH1.

Autofluorescence Endoscopy Improves Detection of Adenomas in Patients with Familial Colorectal Cancer: Preliminary Results of a Back-to-Back Colonoscopy Study

Background: Surveillance colonoscopy is advised in familial colorectal cancer (CRC) syndromes. Especially in hereditary non-polyposis colorectal carcinoma (HNPCC) small or flat neoplastic lesions are prone to progress rapidly into colorectal cancer. These lesions can easily be missed on standard flexible white-light endoscopy (WLE). Autofluorescence endoscopy (AFE) is capable of detecting adenomatous lesions that are not recognized using WLE. The aim of the present study was to compare the sensitivity of autofluorescence endoscopy and white light endoscopy in diagnosing colorectal neoplasia in patients belonging to HNPCC or familial CRC families. Methods: Thirty consecutive asymptomatic patients (mean age 52 years) belonging to HNPCC or familial CRC families (one 1 st degree relative with CRC < 50 years or two 1 st degree relatives with CRC at any age) were recruited for examination with both WLE and AFE. First, standard WLE was performed using a standard video endoscope (CF160, Olympus, Japan). Immediately after the WLE procedure a 2nd endoscopist, unaware of the results of the previous WLE, performed AFE with an autofluorescence endoscopy system (Onco-LIFE, Xillix, Canada). During both procedures all lesions were photographed and videotaped, and graded according to size, morphology, and location. All lesions were judged to be either non-dysplastic or suspicious using both techniques and were removed and collected during AFE. Lesions missed on second pass by AFE were identified and removed on 3rd pass by WLE. Sensitivity and specificity were calculated by correlating positive and negative findings to the pathology results. Results: A total of 31 adenomas were detected in 18 patients. Twelve patients had no abnormalities. White light endoscopy identified 16 adenomas in 9 patients. All these lesions except for one were also found by AFE. This method however identified an additional number of 15 adenomas in 13 patients, thereby significantly increasing the detection rate (p < 0.001). The 15 additionally detected lesions included 4 flat adenomas, 9 small adenomas with a mean size of 2.3 ± 0.7 mm (range 1-3 mm), and two sessile polyps (size 4 mm). The sensitivity of AFE for detecting adenomas was 97% and the specificity was 59%. For WLE the sensitivity and specificity for detecting adenomas was 52% and 71% respectively. Conclusion: Autofluorescence endoscopy significantly improves the detection of colorectal neoplasia in patients with HNPCC or familial colorectal cancer. For this specific population the additional value of autofluorescence endoscopy is mainly in the detection of small or flat lesions.

Metachronous Small Bowel Adenocarcinomas Detected by Capsule Endoscopy in a Patient with Hereditary Nonpolyposis Colorectal Cancer

Hereditary nonpolyposis colorectal carcinoma (HNPCC) is the most common colorectal cancer susceptibility syndrome, with a lifetime risk of colon cancer of 80% [1]. Affected individuals are at risk for extracolonic malignancies as well. These include (in descending order) endometrial, ovarian, gastric, and transition cell carcinoma of the uroepithelial tract. Other more rare HNPCC-associated extracolonic tumors include pancreas, hepatobiliary, brain, skin, and possibly small bowel. The significance of small bowel tumors in HNPCC remains unclear. Two large studies have assessed the risk of extracolonic cancers in HNPCC patients. Vasen et al. [2] observed a very high relative risk (>100-fold) for small bowel cancer in a cohort of 210 mutation carriers. Aarnio et al. [3], however, reviewed a larger cohort of 360 mutation carriers and found no cases of small bowel cancer. Cohort studies have reviewed the clinical pattern of small bowel cancers in HNPCC patients [4–6]. In addition to these larger series, many isolated case reports describe this association [7, 8].

Mechanisms of inactivation of MLH1 in hereditary nonpolyposis colorectal carcinoma: a novel approach

Mutations in the DNA mismatch repair gene MLH1 are a major cause of hereditary nonpolyposis colorectal cancer (HNPCC). No mutant phenotype is observed before the wild-type (wt) allele is somatically inactivated in target tissue. We addressed the mechanisms of MLH1 inactivation in 25 colorectal (CRC) and 32 endometrial cancers (ECs) from MLH1 mutation carriers (Mut1, in-frame genomic deletion; Mut2, out-of-frame splice site mutation; Mut3, missense mutation). By a quantitative method, matrix-assisted laser desorption/ionization-time-of-flight (MALDI-TOF), utilizing four intragenic single nucleotide polymorphisms and mutations, loss of heterozygosity (LOH) was present in 31/57 (54.4%) of tumors. The wt allele displayed LOH more often than the mutant allele (23/57 vs 8/57, P=0.006). For Mut1, LOH was more frequent in CRC than EC (10/11 vs 1/13, P<0.0001), whereas Mut2 and Mut3 displayed opposite LOH pattern. Moreover, although wt LOH predominated in CRC irrespective of the predisposing mutation, LOH often affected the mutant allele in EC from Mut2 and Mut3 carriers (6/19, 31.6%). MLH1 promoter methylation, which reflected a more widespread hypermethylation tendency, occurred in 4/55 (7.3%) of tumors and was inversely associated with LOH. In conclusion, the patterns of somatic events (LOH and promoter methylation) differ depending on the tissue and germline mutation, which may in part explain the differential tumor susceptibility of different organs in HNPCC. MALDI-TOF provides a novel approach for the detection and quantification of LOH.

Survival from Colorectal Carcinoma in HNPCC Families as Compared to the General Population in Lithuania – Initial Results

Colorectal cancer in HNPCC appears to have a better prognosis than sporadic colorectal cancer. Selection bias, screening, early intervention and treatment hamper efforts to confirm such a hypothesis. To evaluate survival rates in Lithuanian HNPCC patients with colorectal cancer and compare them with survival rates of sporadic cases arising from the general population. The study group consisted of 8 patients from 6 Hereditary non-polyposis colorectal carcinoma (HNPCC) families, 3 patients had HMSH2 and 5 patients had HMLH1 mutations, who were diagnosed between 1995 and 1999. HNPCC patients characteristic (age and stage) were used to trace the records of the Cancer Registry at the same period to identify the cases corresponding the required criteria. Above 263 patients were found--106 at stage II and 157 at stage III. The 10-year survival was 87.5% in the HNPCC study group compared with only 44.8% in the general population group. Patients with the MSH2 gene mutation were at a greater risk of developing a second primary cancer independent from any cancer prevention and screening programs. Survival rates were also prolonged even with a greater numbers of extra-colonic cancers diagnosed at different stages. HNPCC patients with confirmed MSH2 or MLH1 mutations diagnosed with stages II and III CRC have a good 10-year survival prognoses compared with those from the general population.