Comprehensive assessment of mismatch repair and microsatellite instability status in molecular classification of endometrial carcinoma / 中华妇产科杂志

Objective: To explore the concordance and causes of different mismatch repair (MMR) and microsatellite instability (MSI) detection results in endometrial carcinoma (EC) molecular typing. Methods: A total of 214 EC patients diagnosed from January 2021 to April 2023 were selected at the Department of Pathology, Peking University Third Hospital. The immunohistochemistry (IHC) results of MMR protein were reviewed. Tumor specific somatic mutations, MMR germline mutations, microsatellite scores and tumor mutation burden (TMB) were detected by next-generation sequencing (NGS) with multi-gene panel. Methylation-specific PCR was used to detect the methylation status of MLH1 gene promoter in cases with deficient MLH1 protein expression. In cases with discrepant results between MMR-IHC and MSI-NGS, the MSI status was detected again by PCR (MSI-PCR), and the molecular typing was determined by combining the results of TMB and MLH1 gene promoter methylation. Results: (1) In this study, there were 22 cases of POLE gene mutation subtype, 55 cases of mismatch repair deficient (MMR-d) subtype, 29 cases of p53 abnormal subtype, and 108 cases of no specific molecular profile (NSMP). The median age at diagnosis of MMR-d subtype (54 years old) and the proportion of aggressive histological types (40.0%, 22/55) were higher than those of NSMP subtype [50 years old and 12.0% (13/108) respectively; all P<0.05]. (2) Among 214 patients, MMR-IHC test showed that 153 patients were mismatch repair proficient (MMR-p), 49 patients were MMR-d, and 12 patients were difficult to evaluate directly. MSI-NGS showed that 164 patients were microsatellite stable (MSS; equal to MMR-p), 48 patients were high microsatellite instability (MSI-H; equal to MMR-d), and 2 patients had no MSI-NGS results because the effective sequencing depth did not meet the quality control. The overall concordance between MMR-IHC and MSI-NGS was 94.3% (200/212). All the 12 discrepant cases were MMR-d or subclonal loss of MMR protein by IHC, but MSS by NGS. Among them, 10 cases were loss or subclonal loss of MLH1 and (or) PMS2 protein. Three discrepant cases were classified as POLE gene mutation subtype. In the remaining 9 cases, 5 cases and 3 cases were confirmed as MSI-H and low microsatellite instability (MSI-L) respectively by MSI-PCR, 6 cases were detected as MLH1 gene promoter methylation and 7 cases demonstrated high TMB (>10 mutations/Mb). These 9 cases were classified as MMR-d EC. (3) Lynch syndrome was diagnosed in 27.3% (15/55) of all 55 MMR-d EC cases, and the TMB of EC with MSH2 and (or) MSH6 protein loss or associated with Lynch syndrome [(71.0±26.2) and (71.5±20.1) mutations/Mb respectively] were significantly higher than those of EC with MLH1 and (or) PMS2 loss or sporadic MMR-d EC [(38.2±19.1) and (41.9±24.3) mutations/Mb respectively, all P<0.01]. The top 10 most frequently mutated genes in MMR-d EC were PTEN (85.5%, 47/55), ARID1A (80.0%, 44/55), PIK3CA (69.1%, 38/55), KMT2B (60.0%, 33/55), CTCF (45.5%, 25/55), RNF43 (40.0%, 22/55), KRAS (36.4%, 20/55), CREBBP (34.5%, 19/55), LRP1B (32.7%, 18/55) and BRCA2 (32.7%, 18/55). Concurrent PTEN, ARID1A and PIK3CA gene mutations were found in 50.9% (28/55) of MMR-d EC patients. Conclusions: The concordance of MMR-IHC and MSI-NGS in EC is relatively high.The discordance in a few MMR-d EC are mostly found in cases with MLH1 and (or) PMS2 protein loss or MMR protein subclonal staining caused by MLH1 gene promoter hypermethylation. In order to provide accurate molecular typing for EC patients, MLH1 gene methylation, MSI-PCR, MMR gene germline mutation and TMB should be combined to comprehensively evaluate MMR and MSI status.

Síndrome de Lynch: aspectos genéticos, clínicos y diagnósticos / Lynch syndrome: genetic, clinical and diagnostic aspects

Esta revisión tiene como objetivo dar a conocer los aspectos genéticos, clínicos y diagnósticos del síndrome de Lynch, además de brindar la información más relevante acerca de la asesoría genética en estos pacientes y las recomendaciones actuales para su seguimiento.

This review aims to present the genetic, clinical and diagnostic aspects of Lynch syndrome, as well as providing the most relevant information about genetic counseling in these patients and the current recommendations for their surveillance.

Síndrome de Lynch: impacto de la caracterización de familias en base a estudios genéticos / Lynch syndrome: impact of the characterization of families based on genetic studies

El objetivo de este trabajo fue caracterizar demográfica y molecularmente las familias con diagnóstico de síndrome de Lynch en base a estudios genéticos. Se utilizó la base prospectiva del Registro de Epidemiología Molecular de Cáncer Colorrectal (REM-CCR) del Hospital Italiano de Buenos Aires (Clinical trials.gov NCT02781337). El criterio de inclusión fue que tuvieran hecho un estudio genético entre 1996 y 2017 (secuenciación y/o determinación de grandes rearreglos de al menos un gen reparador de error de apareamiento). Se analizaron 50 familias con los criterios de Amsterdam. En 23 (46%) se identificaron variantes patogénicas (n=19) y probablemente patogénicas (n=2). El 28.6% de las variantes patogénicas fueron originalmente descritas en esta serie, entre ellas la variante c.1911del en el exón 12 de MSH2 identificada en una familia con agregación de cáncer de mama. Fue identificada una mutación fundadora de Piamonte, Italia (c.2252_2253del). Los genes afectados incluyeron MSH2 (13 variantes) MLH1 (9 variantes) y PMS2 (1 variante). La tasa de detección de mutaciones fue del 46%. Entre las familias con mutación identificada (n=23), se detectó una edad mediana de inicio del cáncer menor (46 vs. 50 años, p=0.02) y mayor incidencia de tumores extra-colorrectales (90.5% vs. 45.8%, p <0.01), que las 27 sin mutaciones. La implementación de estudios genéticos permitió caracterizar variables demográficas en base a la identificación de mutaciones germinales asociadas al síndrome de Lynch, identificándose dos grupos diferenciados por la edad de afectación y la incidencia de tumores extracolónicos (AU)

The aim of this study was to characterize demographically and molecularly families diagnosed with Lynch syndrome based on genetic studies. Families with a genetic study performed between 1996 and 2017 (sequencing and/or determination of large rearrangements of a mismatch repair gene at least) were selected from the prospective database REM-CCR of Hospital Italiano de Buenos Aires (Clinical trials. Gov NCT02781337). Fifty families fulfilled Amsterdam criteria were analyzed. Pathogenic variants were found in 23 out of 50 (46%) families, being 21 pathogenic and 2 likely pathogenic. The 28.6% of the pathogenic variants were originally described in this series. Among them, the variant c.1911del in MSH2 in a family with breast cancer aggregation and a founder MLH1 mutation from Piedmont, Italy (c.2252_2253del) were identified. Affected genes include MSH2 (13 variants), MLH1 (9 variants), PMS2 (1 variant). Mutations detection rates was 46%. Those families with an identified mutation (n=23) had a lower median age of cancer onset (46 vs. 50 years, p=0.02) and a higher incidence of extra-colorectal tumors (90.5% vs. 45.8%, p<0.01) than those without identified mutations (n=27). The implementation of genetic studies allowed characterizing demographic variables based on the identification of germline mutations associated with Lynch syndrome. Two groups, Síndrome de Lynch: impacto de la caracterización de familias en base a estudios genéticos 3 differentiated by the age of cancer onset and the incidence of extracolonic tumors were characterized (AU)

Current evidence for universal molecular testing for colorectal cancer patients / Evidências atuais para testes moleculares universais para pacientes com câncer colorretal

Abstract Background Risk assessment for Lynch Syndrome may be a complex and challenging task. Demonstration of germline mutations has the benefits of confirming Lynch Syndrome diagnosis and may also provide screening and surgical orientation for affected members and relief for non-affected relatives. Objective The present paper aimed to critically review the criteria to diagnose Lynch Syndrome, focusing the attention on the new perspective of adopting universal screening for patients diagnosed with colorectal cancer. Methods We performed a literature review about the rationale and preliminary results of universal testing for Lynch Syndrome. Results The use of selective eligibility criteria to determine who should undergo Lynch Syndrome testing may fail in a substantial proportion of cases. Moreover, universal strategy is feasible, cost-effective and more sensitive than previous methods. However, there still exist problems regarding clinical practice implementation and compliance either by medical doctors and patients. Conclusions Standard guidelines for colorectal cancer screening are not ideal to provide early detection of Lynch Syndrome patients. And although universal screening has been associated with an increased identification of Lynch Syndrome patients, a successful implementation of this approach is still limited by the lack of clinical expertise among physicians, and also requires standardization of the existing protocols for routine genetic screening.

Resumo Introdução A avaliação de risco para síndrome de Lynch (SL) pode ser tarefa complexa e desafiadora. A demonstração de mutações na linha germinal resulta em benefícios, como a confirmação do diagnóstico de SL e também pode proporcionar orientações para a triagem e procedimentos cirúrgicos para os membros afetados, além de trazer alívio para os parentes não afetados. Objetivo Este artigo teve por objetivo oferecer uma revisão crítica dos critérios para o diagnóstico de SL, com enfoque na atenção sobre a nova perspectiva de adoção da triagem universal para pacientes diagnosticados com câncer colorretal (CCR). Métodos Procedemos a uma revisão da literatura com ênfase nas justificativas e resultados preliminares de testes universais para SL. Resultados O uso de critérios seletivos de qualificação, com vistas a determinar quem deveria passar por um teste para SL, pode ser malsucedido em substancial percentual de casos. Foi também constatado que a estratégia universal é exequível, com bom custo-benefício e com maior sensibilidade, em comparação com os métodos previamente utilizados. Contudo, ainda existem problemas concernentes à sua implementação na prática clínica e também na cooperação de médicos e de pacientes. Conclusões As orientações padronizadas para a triagem de CCR não são ideais, em termos de se obter a imediata detecção de pacientes com SL. Por outro lado, embora a triagem universal tenha sido associada a um aumento na identificação de pacientes com SL, a bem-sucedida implementação dessa abordagem fica ainda limitada pela pouca experiência clínica entre os médicos e, além disso, também há a necessidade de padronização dos protocolos existentes para a triagem genética de rotina.

Improving survival after endometrial cancer: the big picture / 부인종양

To improve survival in women with endometrial cancer, we need to look at the "big picture" beyond initial treatment. Although the majority of women will be diagnosed with early stage disease and are cured with surgery alone, there is a subgroup of women with advanced and high-risk early stage disease whose life expectancy may be prolonged with the addition of chemotherapy. Immunohistochemistry will help to identify those women with Lynch syndrome who will benefit from more frequent colorectal cancer surveillance and genetic counseling. If they happen to be diagnosed with colorectal cancer, this information has an important therapeutic implication. And finally, because the majority of women will survive their diagnosis of endometrial cancer, they remain at risk for breast and colorectal cancer, so these women should be counselled about screening for these cancers. These three interventions will contribute to improving the overall survival of women with endometrial cancer.

Investigação de mutações nos genes MLH1 e MSH2 em portadores de câncer colorretal hereditário sem polipose (HNPCC) / Investigation of mutations in MLH1 and MSH2 genes in carriers with Hereditary Nonpolyposis Colorectal Cancer (HNPCC)

O câncer colorretal tem importância elevada frente a sua incidência e morbidade. Dentre os casos hereditários, o câncer colorretal hereditário sem polipose (HNPCC), ou Síndrome de Lynch, é responsável por cerca de 5% do total de casos. No HNPCC, a alteração genética herdada é a inativação de um dos alelos dos genes envolvidos em reparo do DNA, sendo os principais os genes hMLH1 e hMSH2. O objetivo deste trabalho foi investigar, em indivíduos com diagnóstico clínico de HNPCC, a presença de mutações nos genes MLH1 e MSH2, associar as variáveis clínicas com o gene mutado e investigar os familiares de portadores de HNPCC aos quais tivemos acesso, com relação a mutações germinativas. A investigação das mutações foi realizada por meio de sequenciamento direto dos éxons, região promotora e regiões de junção. Foram analisados 65 indivíduos divididos em três grupos, sendo (I) 46 pacientes portadores de câncer colorretal inclusos nos Critérios de Amsterdã, (II) dois familiares portadores de câncer colorretal e (III) 17 familiares sem câncer, todos da região metropolitana de Campinas, atendidos no Hospital de Clínicas da UNICAMP. Em 21 (45,65%) dos pacientes foram encontradas mutações deletérias. As mutações deletérias nos genes MLH1 e MSH2 estavam na proporção de 34,78% (16 pacientes) e 10,86% (5 pacientes), respectivamente. As mutações não deletérias nos genes MLH1 e MSH2 estavam na proporção de 65,22% dos pacientes (30 alterações) e 50% dos pacientes (23 alterações), respectivamente...

Colorectal cancer has high importance because of its incidence and morbidity. Among the hereditary cases, the hereditary nonpolyposis colorectal cancer (HNPCC) or Lynch syndrome, accounts for about 5% of cases. In HNPCC, the genetic alteration inherited is the inactivation of one of the alleles of genes involved in the DNA repair, being hMSH2 and hMLH1 the main genes. The objective of this study is to investigate the presence of mutations in MLH1 and MSH2 in patients with clinical diagnosis of HNPCC, correlate clinical variables with the mutated gene, and investigate the relatives of patients with HNPCC who we had access to, in relation to germline mutations. Investigation of the mutations was performed by éxons direct sequencing, the promoter and junction regions. Sixty-five individuals, divided into three groups, were studied: (I) 46 patients with colorectal cancer included in the Amsterdam Criteria, (II) two family members of colorectal cancer patients and (III) 17 relatives without cancer, all of them treated at Hospital das Clínicas at UNICAMP and living in the Campinas metropolitan area. Deleterious mutations were found in 21 patients (45.65%). The ratio of deleterious mutations in MLH1 and MSH2 was 34.78% (16 patients) and 10.86% (5 patients) respectively. The ratio of non deleterious mutations in genes MLH1 and MSH2 was 65.22% of patients (30 alterations) and 50% of patients (23 alterations) respectively. Among patients with HNPCC, 23 potentially deleterious mutations were identified, via sequences of MLH1 and MSH2 with a 50% detection rate. It doesn't seem to appear variations in the clinical characteristics of the tumor when a germline mutation occurs in MLH1 or MSH2, with the exception of the relationship between the presence of mutation in the MLH1 gene and age of disease onset. As it occurs throughout the world, the disease present a his molecular extremely heterogeneoty, where only two mutations were repeated in two patients...

Historical review of Lynch syndrome / Revisão histórica da síndrome de Lynch

Lynch syndrome was formerly known as Hereditary Nonpolyposis Colorectal Cancer. Currently, these two nomenclatures each have their unique definitions and are no longer used interchangeably. The history of hereditary nonpolyposis colorectal cancer was first recognized formally in the literature by Henry Lynch in 1967. With advances of molecular genetics, there has been a transformation from clinical phenotype to genotype diagnostics. This has led to the ability to diagnose affected patients before they manifest with cancer, and therefore allow preventative surveillance strategies. Genotype diagnostics has shown a difference in penetrance of different cancer risks dependent on the gene containing the mutation. Surgery is recommended as prevention for some cancers; for others they are reserved for once cancer is noted. Various surveillance strategies are recommended dependent on the relative risk of cancer and the ability to intervene with surgery to impact on survival. Risk reduction through aspirin has shown some recent promise, and continues to be studied. (AU)

A síndrome de Lynch era anteriormente conhecida como "câncer colorretal hereditário não polipose". Atualmente, essas duas nomenclaturas têm, cada uma, sua própria definição original e já não são empregadas de forma intercambiável. O histórico de câncer colorretal hereditário não polipose foi formalmente reconhecido pela primeira vez na literatura por Henry Lynch em 1967. Com os avanços da genética molecular, verificou-se uma mudança do fenótipo clínico para o diagnóstico genotípico. Esse fato levou à capacidade de diagnosticar pacientes afetados antes que o câncer se manifestasse, e, portanto, à utilização de estratégias preventivas de rastreamento. O diagnóstico genotípico mostrou a diferença na penetrância de diferentes riscos de câncer dependendo do gene que contem a mutação. A cirurgia é recomendada para a prevenção de alguns tipos de câncer; para outros, ela é reservada quando há o aparecimento da doença. Várias estratégias de rastreamento são recomendadas, dependendo do risco relativo de câncer, bem como a capacidade para intervir com a cirurgia objetivando um impacto na sobrevivência. A redução do risco através do uso de aspirina recentemente mostrou ser promissor e continua a ser estudada. (AU)

Adenocarcinoma of rectum as second primary cancer after treatment of endometrium cancer

Colorectal cancer is the second leading cause of death from cancer in women in the United States. Previous epidemiologic studies have identified a 1.5 - 3 fold increased risk of colorectal cancer in women after ovarian and endometrial cancer. In Pakistan, neither such a study showing relationship of colorectal cancer with gynaecological cancer has been done nor any case has been reported. Here, a case is being reported who developed adenocarcinoma of rectum as the second primary about nine years after completion of treatment for adenocarcinoma of endometrium

Genómica en el diagnóstico del cáncer colorrectal hereditario / Genetics in diagnosis of hereditary colorectal cancer

Introducción: El cáncer colorrectal (CCR) se presenta en el 3 - 5% como formas hereditarias. Existen 4 síndromes en donde se han descubierto mutaciones responsables, el síndrome de Lynch (SL), la Poliposis Adenotamosa Familiar (PAF), la Poliposis Juvenil (PJ) y el síndrome de Peutz-Jeghers (SPJ). Cada uno de ellos presenta una patente genética distinta, vías de carcinogénesis y comportamientos distintos. Los conocimientos actuales sobre las mismas son limitados y los abordajes diagnósticos controvertidos. Material y Métodos: Se ha realizado la búsqueda bibliográfica sobre las técnicas de biología molecular que permiten detectar las mutaciones en los síndromes de CCR hereditario, así como las guías y estrategias diagnósticas. Se presenta una breve reseña sobre conceptos básicos de genómica y técnicas de biología molecular y luego sus usos en la práctica clínica en estas 4 enfermedades. Resultados: Hemos encontrado que con el avance de las técnicas de biología molecular cada día es mayor el conocimiento con respecto a la base genética de estas enfermedades. Esto provoca un impacto tanto en el diagnóstico como en la terapéutica y seguimiento. Las guías actuales de manejo muestran consenso en gran cantidad de puntos aunque todavía queda campo por explorar. Conclusiones: Hacen falta futuros ensayos que nos permitan arribar a estrategias de manejo en cada subgrupo de pacientes seguramente basados en las distintas patentes genotípicas. Esto permitirá un manejo más personalizado en el futuro del cáncer colorrectal hereditario.

Introduction: 3 - 5% of colorectal cancer (CRC) occurs as hereditary forms. There are 4 syndromes in which mutations have been found responsible, the Lynch syndrome (LS), the Family Adenotamosa polyposis (FAP), Juvenile Polyposis (JP) and Peutz-Jeghers syndrome (PJS). Each one has a distinct genetic patent, different process of carcinogenesis and different behaviors. Current knowledge about them is limited and the diagnostic approaches are controversial. Material and methods: We performed literature searches on molecular biology techniques to detect mutations in hereditary CRC syndromes and diagnostic guidelines and strategies. A review of basic concepts of genomics and molecular biology techniques are presented and then their uses in clinical practice in these 4 diseases. Results: We have found that with the progress of molecular biology techniques is growing the knowledge about the genetic basis of these diseases. This causes an impact on both diagnosis and therapy and monitoring. Current guidelines show consensus in handling large amount of points but there is still room to explore. Conclusions: Future trials are needed to enable us to arrive at management strategies in each subgroup of patients likely based in different genotypic patents. This will allow a more personalized management in the future of hereditary colorectal cáncer.

Síndrome de Lynch: selección de pacientes para el estudio genético mediante análisis de inestabilidad microsatelital e inmunohistoquímica / Lynch syndrome: selection of families by microsatellite instability and immunohistochemistry

Background: Selection of patients with Lynch Syndrome (LS) for a genetic study involves the application of clinical criteria. To increase the rate of identification of mutations, the use of molecular studies as Microsatellite Instability (MSI) and Im-munohistochemistry (IHC) in the tumor has been proposed. Aim: To demonstrate the usefulness of MSI and IHC in the detection of mutations in patients with LS. Material and Methods: From our Familial Colorectal Cancer Registry, families suspected of LS were selected according to Amsterdam or Bethesda clinical criteria. Screening of germline mutations of MLH1, MSH2 and MSH6 genes was performed. In addition, analysis of MSI and IHC were performed in colorectal tumors. Results: A total of 35 families were studied (19 met Amsterdam and 16 met Bethesda criteria). Twenty one families harbored a germline alteration in MLH1, MSH2 or MSH6 (18 Amsterdam and 3 Bethesda). In these families, eighteen different alterations were found, 15 of which were mutations and 3 corresponded to variants of uncertain pathogenicity. On the other hand, 80% of the tumors showed positive microsatellite instability (27 MSI-high and 1 MSI-low), and immunohistochemical testing showed that 77% of tumors had the loss of a protein. Correlation between results of tumor molecular studies and the finding of germline nucleotide change showed that IHC and MSI predicted mutations in 81 and 100% of patients, respectively. Conclusions: MSI and IHC can efficiently select patients with a high probability of carrying a mutation in DNA repair genes.

Cáncer colorrectal hereditario no ligado a poliposis (Síndrome de Lynch): presentación de un caso / Hereditary colorectal cancer unlinked to polyposis (Lynch Syndrome): a case presentation

Se trata de un paciente joven de 27 años de edad, con antecedentes patológicos familiares de varios fallecidos por cáncer colorrectal que acude a consulta por presentar desde hace aproximadamente dos o tres meses cuadro de dolor abdominal localizado a nivel de epigastrio-hipocondrio derecho, acompañado de un síndrome general y anemia. Al examen físico lo más llamativo resultó ser la palidez cutáneo-mucosa, la cual estaba en correspondencia con cifras de hemoglobina bajas. El resto del estudio hematológico se encontraba dentro de los parámetros normales al igual que la ecografía abdominal, la radiografía del tórax y la esofagogastroduodenoscopia. Se le realiza una colonoscopia, diagnosticándosele un proceso neoproliferativo del ángulo hepático del colon, diagnóstico que fue confirmado por histología como adenocarcinoma bien diferenciado del colon. El paciente fue intervenido quirúrgicamente, realizándosele una hemicolectomía derecha con ileo-tranversostomía. El estudio histológico del segmento resecado se correspondió con el diagnóstico preoperatorio.

This is a young patient of 27 years old, with family medical history of several deaths from colorectal cancer, who goes to the doctor for presenting about two or three months, abdominal pain located at level of right epigastrium-hypochondrium, accompanied by a general syndrome and anemia. The most striking at physical examination was the mucous cutaneous pallor, which was in correspondence with low hemoglobin. The rest of the hemathologic study was within normal parameters as well as abdominal ultrasound, thorax radiography and esophagogastroduodenoscopy. He underwent a colonoscopy, diagnosed him a neoproliferative process from hepatic flexure of colon, this diagnosis was confirmed by histology as well-differentiated adenocarcinoma of colon. The patient underwent surgery; a right hemicolectomy with ileo-transversostomy was done. The histologic examination of the resected segment was corresponded with the preoperative diagnosis.

A importância da suspeição clínica no diagnóstico e tratamento do câncer colorretal hereditário / The importance of clinical suspicion on the diagnosis and treatment of hereditary colorectal cancer

Neste trabalho relatamos o caso de um paciente portador de síndrome de Lynch (HNPCC) que desenvolveu câncer retal metacrônico em curto intervalo de tempo após tratamento do tumor primário (câncer de cólon direito). O objetivo deste relato de caso é salientar a importância da suspeição clínica no diagnóstico de câncer colorretal hereditário e suas implicações terapêuticas.

In this article we report the case of a patient with Lynch syndrome (HNPCC) who developed metachronic rectal cancer in a short time interval after the primary tumor had been treated (right colon cancer). The objective of this case report is to point out the importance of clinical suspicion in the diagnosis of hereditary colorectal cancer and its therapeutics implications.

Análisis genético en pacientes con cáncer colorrectal / Microsatellite instability among patients with colorectal cancer

Background: In patients with colorectal carcinoma, insertions or deletions of short sequences of DNA, a phenomenon called microsatellite instability, are observed. Aim: To look for microsatellite instability and mutations of MLH1 and MSH2 gene mutations in patients with colorectal carcinoma. Material and Methods: Ten patients with sporadic colorectal carcinoma and 31 patients fulfilling criteria for hereditary nonpolyposis colon cancer (HNPCC), aged 9 to 70 years, were studied. Microsatellite instability was studied in samples of tumor and peripheral blood mononuclear cell DNA. Six markers were amplified by polymerase chain reaction and capillary electrophoresis. In samples with microsatellite instability, mutations of MLH1 and MSH2 genes were studied by direct sequencing. Results: Thirty four percent of patients had microsatellite instability and among these, 76 percent had a high degree of instability. BAT40 marker had the higher frequency of instability. No mutations for MLH1 and MSH2 genes were observed. However a new polymorphism, C399T, was identified in exon 3 of MSH2 gene. This polymorphism was observed both in patients with sporadic colorectal carcinoma and patients with HNPCC. Conclusions: There is a high frequency of microsatellite instability among patients with colorectal cancer. A new polymorphism, not previously reported, was identified in MSH2 gene.

Cáncer colorrectal no polipóideo (Síndrome de Lynch) / Non poliposys colorectal cancer (Lynch syndrome)

Cancer of the large intestine (colon and rectum) is the most frequent neoplasm of the GL tract. The clinical importance of this disease is based both on its frequent occurrence and the fact that its early detection may lead to a substantial imporvement in autcome. The step wise progression from normal mucosa to cancer is better understood in the colon than in any other GI organ. Adenomas which begin in flat mucosa, are the earliest histologically identifiable neoplastic lesions. patients with adenomatous polyps are at greater risk for subsequent development of cancer...The early detection of this complaint, including genetic tests and diagnostic features, treatment and postoperative follow-ups, are described in the article.

Hereditary nonpolyposis colorectal cancer identification and surveillance of high-risk families

O câncer colo-retal hereditário não polipose é uma síndrome genética caracterizada por uma susceptilidade aumentada para certos tipos específicos de câncer, especialmente o câncer colo-retal. Ao nível molecular, a síndrome caracteriza-se pela herança autossômica dominante de mutações em genes envolvidos em um mecanismo de reparo do DNA dirigido para defeitos em trocas, ganhos ou perdas de um número de pequeno de bases, chamado de sistema de reparo de erros de pareamento. Os genes mais comumente afetados em câncer colo-retal hereditário não polipose são hMLH1 e hMSH2, e sua inativação destina a célula portadora à acumulação de mutações, uma condição conhecida como fenótipo de erro de replicação. Estas mutações múltiplas serão transmitidas e amplificadas em células-filhas e sua identificação pode ser feita por meio da identificação de distúrbios em seqüências repetidas de DNA chamadas de microssatélites. Células portadoras de defeitos deste tipo em seus microssatélites apresentam um fenótipo denominado de instabilidade de microssatélites (também denominado fenótipo MSI). Por meio da detecção destes defeitos genéticos é possível, presentemente, a realização de um diagnóstico preciso de câncer colo-retal hereditário não polipose, permitindo a atuação preventiva em portadores da síndrome que ainda não desenvolveram câncer. Contudo, limitações financeiras e de acesso aos exames inviabilizam sua realização em todos os indivíduos que apresentam câncer colo-retal. Por isso, foram estabelecidos pela comunidade internacional alguns critérios que selecionam as famílias com alta probabilidade de possuírem a mutação e que, portanto, podem beneficiar-se com estes exames. Este artigo procura abordar as estratégias recomendadas para identificação de casos de alto risco de câncer colo-retal hereditário não polipose, os testes genéticos disponíveis para estes casos e as recomendações para prevenção e seguimento destas famílias.

Hereditary non-polipomatous colorectal cancer: hereditary predisposition, diagnosis and prevention

RACIONAL: O câncer colorretal é o terceiro tumor em freqüência e o segundo em mortalidade nos países desenvolvidos. No Brasil, está entre as seis neoplasias malignas mais encontradas e é a terceira em mortalidade. Cerca de 20% dos tumores colorretais têm etiologia hereditária. OBJETIVO: Revisão sobre aspectos genéticos e clínicos, bem como diagnóstico, tratamento e prevenção na síndrome do câncer colorretal hereditário não-polipomatoso, que apresenta a forma mais freqüente de câncer colorretal hereditário. A importância dessas abordagens se deve, principalmente, à possibilidade de manejo, prevenção e rastreamento específico para indivíduos em risco para câncer colorretal hereditário não-polipomatoso que conferem um aumento considerável na sobrevida desses pacientes e seus familiares em risco.

Diagnóstico clínico de HNPCC: caracterização de famílias "Amsterdam" positivas / Clinical diagnosis of HNPCC: characterization of positive families \"Amsterdam\"

A utilização dos critérios de Amsterdam permanece ainda hoje o método mais acessível para o diagnóstico de HNPCC, uma vez que testes genéticos são pouco disponíveis e têm seu emprego restrito a centros de alta complexidade. Contudo, a maioria das informações clínico-epidemiológicas relativas ao HNPCC deriva das populações da Europa setentrional e dos Estados Unidos da América, sendo os dados brasileiros praticamente inexistentes. Objetivo: Caracterização clínico-epidemiológica de famílias brasileiras com diagnóstico clínico de HNPCC. Pacientes e Método: 20 famílias que preenchem os critérios de Amsterdam foram avaliadas através entrevista para obtenção de dados clínico-epidemiológicos e os tumores dos casos índice submetidos ao teste de instabilidade de microssatélites. Resultados: A média de idade ao diagnóstico de CCR foi de 49 anos e de 48,5 anos para tumores extra-cólicos. Identificaram-se 103 casos de CCR em 94 indivíduos; e 88 casos de cânceres extra-cólicos em 86 pacientes. Os tumores extra-cólicos mais freqüentes relacionados ao HNPCC foram: gástrico, de ovário e endométrio. Entre outros tumores de grande prevalência encontraram-se o câncer de mama e de próstata. 65por cento dos CCR apresentaram alta instabilidade de microssatélites, 15por cento baixa instabilidade e 20por cento foram estáveis. Discussão: Os dados clínico-epidemiológicos nesta série de famílias brasileiras portadoras de HNPCC parecem se sobrepor aos dados mundiais existentes, especialmente em relação à forma e idade de apresentação do CCR e câncer extra-cólico. Espera-se que a implementação de registros permita a obtenção de um perfil próprio do HNPCC em nossa população, com os benéficos da redução do impacto desta doença nos pacientes acometidos.