Diagnostic approach and management of Lynch syndrome (hereditary nonpolyposis colorectal carcinoma): a guide for clinicians

ABSTRACT diagnostic workup of familial colorectal cancer is an elaborate and time consuming process in which the family and several medical specialists closely collaborate. However, establishing a diagnosis can be very rewarding. If a mutation is detected in the family, a satisfactory explanation can be provided for an accumulation of tumors at young age, and often of untimely death. Appropriate presymptomatic testing can be offered to reduce mortality among at-risk family members, and relatives not at risk can avoid uncertainty and needlessly intensive surveillance. We show the differential diagnostic considerations when an individual with a family history of colorectal carcinoma is encountered, with emphasis on Lynch syndrome (Hereditary Nonpolyposis Colorectal Carcinoma [HNPCC]). Practical recommendations for laboratory workup of suspected Lynch syndrome, including analysis of tumor tissue by microsatellite instability analysis and immunohistochemistry, and germline DNA analysis are given. Furthermore, the clinical management after a molecular diagnosis has been made is described. The diagnostic scheme presented here allows efficient and effective analysis of colorectal carcinoma cases with (suspected) Lynch syndrome, making optimal use of currently available technology.     

Gynecologic Cancers in Lynch Syndrome/HNPCC

Recent studies have estimated that the lifetime risk of endometrial cancer in women with Lynch syndrome/hereditary non-polyposis colorectal cancer syndrome (Lynch/HNPCC) is 40–60%. This risk equals or exceeds their risk for colon cancer. While much research has been done to define the natural history and molecular features of Lynch/HNPCC associated colon cancer, there has been considerably less research defining Lynch/HNPCC associated endometrial cancer. This article will review current information regarding the clinico-pathologic features of Lynch/HNPCC associated endometrial cancer. In addition, current consensus guidelines for endometrial cancer screening and prevention for women with Lynch/HNPCC will be discussed. Given the increased risk of multiple cancers, changing the name of this syndrome from hereditary non-polyposis colorectal cancer syndrome to Lynch Syndrome may benefit both patients and clinicians. Clinicians caring for women with Lynch/HNPCC may stress colon cancer screening and prevention without reviewing endometrial cancer risks and symptoms or screening and prevention options. Perhaps more importantly, women with Lynch/HNPCC may focus on colon cancer risks and lack understanding of endometrial cancer risks. With increasing evidence that women with Lynch/HNPCC have significant risks for both colon and endometrial cancers, we believe a multi-disciplinary approach to the management of these individuals is crucial.     

Lynch综合征筛查及治疗研究进展

家族遗传性结直肠癌是一类由于基因胚系变异导致的疾病,其中最常见的是Lynch综合征,也被称为遗传性非息肉病性结直肠癌（hereditary nonpolyposis colorectal cancer,HNPCC）。近年来随着对基因组认识的加深,研究显示Lynch综合征临床表型和治疗靶点均有别于散发型结直肠癌。本文将从Lynch综合征筛查策略、类Lynch综合征再定义,以及Lynch综合征免疫治疗和化学预防等方面综述其研究进展。      

Laryngeal carcinoma in a Lynch syndrome II kindred

Hereditary nonpolyposis colorectal cancer (HNPCC) accounts for about 4% to 6% of the total colorectal cancer burden. It is subdivided into Lynch syndrome I and II. Lynch syndrome I is characterized by an autosomal dominant inheritance pattern for site-specific, early onset, adenocarcinoma of the colon, with proximal predominance and an excess of synchronous and metachronous colonic cancers. Lynch syndrome II (cancer family syndrome) shows these same colon cancer characteristics, but differs in that there is an excess proclivity of other forms of cancer, particularly of the endometrium and ovary. This article documents a family that shows features of Lynch syndrome II. Unique aspects pertain to a patient who is in the direct genetic lineage (whose five brothers manifested colonic cancer), but who developed carcinoma of the uterine cervix at age 34 and laryngeal cancer at 60. The pedigree also shows uterine cervical carcinoma among other patients at genetic risk. Her son, who is a nonsmoker and nondrinker, manifested laryngeal cancer at age 31. These observations appear to add new information about tumor heterogeneity in HNPCC.     

Hereditary nonpolyposis colorectal cancer

Hereditary nonpolyposis colorectal cancer (HNPCC), or Lynch syndrome, is the most common form of hereditary colorectal cancer (CRC). A well-orchestrated cancer family history is essential for its diagnosis since, unlike its familial adenomatous polyposis (FAP) hereditary cancer counterpart, HNPCC lacks distinguishing clinical stigmata of its cancer genetic risk. Discoveries in the 1990s of germ-line mutations, the most common of which are hMSH2 and hMLH1, have added enormous power to the diagnosis of Lynch syndrome. Its medical management is contingent upon its natural history. For example, approximately 70% of CRCs occur proximal to the splenic flexure, with one-third of the cancers occurring in the cecum, thereby mandating full colonoscopy. A high rate of metachronous CRCs indicates the need for no less than a subtotal colectomy for the management of initial CRC. Genetic counseling is essential prior to DNA testing, and at the time of disclosure of the results. Education of patients as well as physicians about all facets of this disorder is extremely important. If patients are to show compliance with germ-line testing, screening, and management options, they must understand the natural history and the significance of their genetic risk status. Physicians must also be aware of clinical nuances of this disorder to provide the necessary care.     

Tracking mutations in a family: Recognizing indicators of germline mutation in Lynch syndrome

An average individual has a lifetime risk of about 5% for developing colorectal cancer. In up to 20% of patients, colorectal cancer arises on the basis of an underlying genetic predisposition. Hereditary nonpolyposis colorectal cancer (HNPCC, Lynch syndrome) is the most common form of hereditary colorectal cancer and is associated with heritable mutations in DNA mismatch repair genes. It is important to recognize patients with Lynch syndrome because their lifetime risk of developing colorectal or extracolonic cancer exceeds 90% but cancer is preventable by appropriate surveillance. This review summarizes the different approaches proposed to improve the likelihood of detecting a Lynch syndrome mutation in various cohorts of individuals. These diagnostic tools may be based on clinical and family features or tumor characteristics, followed by the direct demonstration of sequence changes and the final interpretation of their consequences.     

The tumour spectrum in hereditary non-polyposis colorectal cancer: a study of 24 kindreds in the Netherlands

The hereditary colonic cancer syndrome without polyposis, hereditary non-polyposis colorectal cancer (HNPCC), is usually divided into 2 main categories: hereditary site-specific colorectal cancer (Lynch syndrome I) and colorectal cancer in association with other forms of cancer (Lynch syndrome II). One problem associated with Lynch II is the uncertainty as to which types of cancer form part of the hereditary tumour spectrum. The present study was performed to obtain more information about the tumour spectrum of HNPCC. In the 24 HNPCC families studied, 104 patients had colorectal cancer (mean age at diagnosis: 46 years) and in 4 of the families this was the only type of cancer to occur. Sixty-five extra-colonic tumours were diagnosed in 20 families. Endometrial carcinoma was found in 16 patients belonging to 12 families. Cancer of the stomach occurred in 10 patients representing 5 families, and mainly in the older generations. Urinary-tract tumours were found in 8 patients from 4 families. Second primary tumours were diagnosed in 13 of the 16 patients with endometrial cancer, in 4 of the 10 patients with stomach cancer and in 7 of the 8 patients with a urinary-tract tumour. Many other types of carcinoma were found as well, but less frequently. In our families, the trait appears to be transmitted by patients with cancer of the stomach, endometrium or urinary tract, because some of their children have developed colorectal cancer. The findings suggest that, in these 24 HNPCC families, carcinomas of the endometrium, stomach and urinary tract belong to the hereditary tumour spectrum. Definite assignment of tumours to this spectrum will become possible only after a sensitive and specific biomarker becomes available. The screening programme should depend on which and how many extra-colonic tumours occur in a family.     

Risk of endometrial cancer for women diagnosed with HNPCC‐related colorectal carcinoma

The risk of endometrial cancer (EC) subsequent to a diagnosis of colorectal cancer in women with a germline mutation in a mismatch repair gene [Lynch syndrome or hereditary non‐polyposis colon cancer (HNPCC)] is unknown. We estimated the risk of EC following a diagnosis of colorectal carcinoma (CRC) for women with Lynch syndrome. A retrospective cohort study was performed on women diagnosed with CRC with a germline mutation in a mismatch repair (MMR) gene (Lynch syndrome cases), and women with microsatellite stable (MSS) CRC who were not known to carry a germline mutation (non‐Lynch cases), identified from the Colon Cancer Family Registry. The incidence of EC following CRC was estimated and compared for women with and without Lynch syndrome, using adjusted hazards ratios calculated for time at risk among each group. A total of 112 women with Lynch syndrome and a previous diagnosis of CRC were compared with 908 women without Lynch and with a MSS CRC diagnosis. The estimated 10‐year cumulative risk of EC subsequent to CRC was 23.4% [95% confidence interval (CI): 15–36%] for Lynch syndrome women compared with 1.6% (95% CI: 0.7–3.8%) for non‐Lynch women. After adjusting for ascertainment, age at diagnosis and diagnosis of other cancers, risk of subsequent diagnosis with EC was elevated sixfold in women with Lynch syndrome compared with non‐Lynch women (HR 6.2; 95% CI 2.2–17.3; p = 0.001). Approximately one quarter of women diagnosed with Lynch syndrome‐associated CRC developed EC within 10 years. This supports the sentinel cancer concept and suggests that active and early management is important for these women.     

Exclusion of breast cancer as an integral tumor of hereditary nonpolyposis colorectal cancer

Hereditary nonpolyposis colorectal cancer (HNPCC) is an autosomal dominant genetic predisposition syndrome that accounts for 2-7% of all colorectal cancers. Diagnosis of HNPCC is based on family history (defined by Amsterdam or Bethesda Criteria), which often includes a history of multiple synchronous or metachronous cancers. The majority of HNPCC results from germ-line mutations in the DNA mismatch repair (MMR) genes hMSH2 and hMLH1 with rare alterations in hMSH6 and hPMS2 in atypical families. Both HNPCC and sporadic MMR-deficient tumors invariably display high microsatellite instability (MSI-H). Two types of HNPCC families can be distinguished: type I (Lynch I) with tumors exclusively located in the colon; and type II (Lynch II) with tumors found in the endometrium, stomach, ovary, and upper urinary tract in addition to the colon. A proposed association of breast cancer with type II HNPCC is controversial. To address this important clinical question, we examined MSI in a series of 27 female patients who presented with synchronous or metachronous breast plus colorectal cancer. Although MSI-H was found in 5 of 27 (18.5%) of the colon cancers, in all cases the matched breast cancer was microsatellite stable. We also examined the breast tumors from three women who were carriers of MMR gene mutations from HNPCC families. None of these three breast tumors displayed MSI nor was the expression of MMR proteins altered in these tumors. We conclude that breast cancer largely arises sporadically in HNPCC patients and is rarely associated with the HNPCC syndrome.     

遗传性非腺瘤病性结直肠癌的诊治进展

遗传性非腺瘤病性结直肠癌（HNPCC）是一种常染色体显性遗传的综合症,占总的结直肠癌的56%--10%。该病由错配修复基因缺陷造成,肿瘤表现出高度的微卫星不稳。临床上辨别HNPCC患者对诊断和治疗以及监测HNPCC家庭成员发病有指导意义。     

What the physician needs to know about Lynch syndrome: an update

The Lynch syndrome (hereditary nonpolyposis colorectal cancer [HNPCC]), is the most common form of hereditary colorectal cancer (CRC), accounting for 2% to 7% of all CRC cases. The next most common hereditary CRC syndrome is familial adenomatous polyposis (FAP), which accounts for less than 1% of all CRC. Lynch syndrome is of crucial clinical importance due to the fact that it predicts the lifetime risk for CRC and a litany of extra-CRC cancers (of the endometrium, ovary, stomach, small bowel, hepatobiliary tract, upper uroepithelial tract, and brain) through assessment of a well-orchestrated family history. A Lynch syndrome diagnosis is almost certain when a mutation in a mismatch repair gene--most commonly MSH2, MLHI, or, to a lesser degree, MSH6--is identified. Once diagnosed, the potential for significant reduction in cancer-related morbidity and mortality through highly targeted surveillance may be profound. Particularly important is colonoscopy initiated at an early age (ie, 25 years) and repeated annually due to accelerated carcinogenesis. In women, endometrial aspiration biopsy and transvaginal ultrasound are important given the extraordinarily high risk for endometrial and ovarian carcinoma. These cancer control strategies have a major impact on at-risk family members once they have been counseled and educated thoroughly about Lynch syndrome's natural history and their own hereditary cancer risk.     

Fas Ligand Expression in Lynch Syndrome-Associated Colorectal Tumours

Fas Ligand (FasL) expression by cancer cells may contribute to tumour immune escape via the Fas counterattack against tumour-infiltrating lymphocytes (TILs). Whether this plays a role in colorectal carcinogenesis in Lynch syndrome was examined studying FasL expression, tumour cell apoptosis and number of TILs in colorectal neoplasms from Lynch syndrome patients (50 adenomas, 20 carcinomas) compared with sporadic cases (69 adenomas, 52 carcinomas). FasL expression was observed in 94% of Lynch syndrome adenomas and in all carcinomas. FasL expression patterns and apoptotic indices were similar in Lynch syndrome-associated neoplasms and sporadic cases. The number of TILs was higher in Lynch syndrome neoplasms than in sporadic cases. There were no correlations between FasL expression and tumour cell apoptosis or number of TILs in Lynch syndrome-associated neoplasms. So, FasL expression is an early event in Lynch syndrome and sporadic colorectal carcinogenesis, but not related to TIL number. Taken together, our data do not support a role for the Fas counterattack in colorectal carcinogenesis in Lynch syndrome.     

Working through a diagnostic challenge: colonic polyposis,Amsterdam criteria,and a mismatch repair mutation

The two most common causes of hereditary colorectal cancer are Lynch syndrome and familial adenomatous polyposis (FAP). The phenotype of Lynch syndrome, also known as hereditary nonpolyposis colorectal cancer (HNPCC), is differentiated in part from FAP by the lack of profuse colonic polyposis. Here we describe a proband who presented with greater than 50 adenomatous colonic polyps prior to developing cancer of the colon and urinary bladder, and a family history that fulfills the Amsterdam criteria. Germline analyses of APC and MYH in the proband did not reveal any mutations. Comprehensive analysis of the mismatch repair genes associated with Lynch syndrome revealed a germline hMSH6 missense mutation 2314C>T (arg772trp) and normal sequencing for hMSH2 and hMLH1. We outline evidence supporting the pathogenicity of the identified hMSH6 mutation (arg772trp) and suggest possible etiologies for the unexplained colonic adenomatous polyposis.     

Genetic counseling and cascade genetic testing in Lynch syndrome

Lynch syndrome is the most common cause of inherited colorectal and endometrial cancers. Individuals with Lynch syndrome have a 10–80 % lifetime risk for colorectal cancer and a 15–60 % lifetime risk for endometrial cancer. Both cancers are preventable through chemoprevention, intensive cancer surveillance, and risk-reducing surgery options. Efforts to identify as many individuals with Lynch syndrome as possible will prevent cancers and save lives. This includes the traditional cancer genetic counseling model whereby individuals with and without cancer are evaluated for a possible Lynch syndrome diagnosis based on their personal and family history of colon polyps and cancers. It also includes universal tumor screening for Lynch syndrome whereby all individuals with colorectal or endometrial cancer are screened for tumor features of Lynch syndrome at the time of diagnosis. Those with tumors suspicious for Lynch syndrome are referred for cancer genetic counseling regardless of their family history of cancer. This two approaches must be maximized to attain high patient reach. Finally, and perhaps most importantly, cascade testing among the at-risk relatives of those diagnosed with Lynch syndrome is critically important to maximize the diagnosis of individuals with Lynch syndrome. In fact, the cost-effectiveness of universal tumor screening for Lynch syndrome relies entirely on counseling and testing as many at-risk individuals as possible since young unaffected individuals stand to benefit the most from an early diagnosis of Lynch syndrome. This approach must be optimized to achieve high family reach. It will take a concerted effort from patients, clinicians and public health officials to improve current approaches to the diagnosis of Lynch syndrome and the prevention and treatment of Lynch syndrome-associated cancer but these lessons can be applied to other conditions as the ultimate example of personalized medicine.     

Women with synchronous primary cancers of the endometrium and ovary: do they have Lynch syndrome?

PURPOSE: Lynch syndrome (hereditary nonpolyposis colorectal cancer; HNPCC) is an autosomal-dominant cancer predisposition syndrome that increases risk for multiple cancers, including colon, endometrial, and ovarian cancer. Revised Bethesda Criteria recommend that patients with two HNPCC-associated cancers undergo molecular evaluation to determine whether they have a mismatch repair (MMR) defect associated with HNPCC. The purpose of our study was to determine the likelihood of MMR defects (MSH2, MSH6, MLH1) in women with synchronous endometrial and ovarian cancer. PATIENTS AND METHODS: Between 1989 and 2004, 102 women with synchronous endometrial and ovarian cancers were identified; 59 patients had tumor blocks available for analysis. Patients were divided into risk groups based on family history: high (met Amsterdam criteria), medium (personal history or first-degree relative with an HNPCC-associated cancer), and low (all others). Protein expression for MSH2, MSH6, and MLH1 was evaluated by immunohistochemistry. Microsatellite instability and MLH1 promoter methylation analyses were performed on a subset of cases. RESULTS: Median age was 50 years. Two patients met Amsterdam criteria for HNPCC. Five additional patients, all medium-risk, had molecular findings consistent with a germline mutation of either MSH2 or MLH1. None of the low-risk patients had molecular results consistent with a germline mutation. CONCLUSION: Overall, 7% of women in our cohort met either clinical or molecular criteria for Lynch syndrome. All of these women had a prior history or a first-degree relative with an HNPCC-associated cancer. Limiting genetic evaluation to women with synchronous endometrial and ovarian cancer who have a family history suggestive of HNPCC may appropriately identify women with Lynch syndrome.     

Evolution of the Nomenclature for the Hereditary Colorectal Cancer Syndromes

The hereditary forms of colorectal cancer have been given many names historically as the manifestations have been gradually understood. Lynch syndrome has had several names, most prominently ‘Hereditary Nonpolyposis Colorectal Cancer’ or HNPCC. Clarification of the genetic basis and full phenotypic expression of this disease mandates a more clinically useful name that clarifies the consideration of non-colonic cancers in a family history, and unifies the diagnosis around the germline mutation in a DNA mismatch repair (MMR) gene. The term ‘Lynch syndrome’ is proposed for the autosomal dominant disease caused by a germline mutation in a DNA MMR gene.     

HNPCC (Lynch Syndrome): Differential Diagnosis,Molecular Genetics and Management - a Review

HNPCC (Lynch syndrome) is the most common form of hereditary colorectal cancer (CRC), wherein it accounts for between 2-7 percent of the total CRC burden. When considering the large number of extracolonic cancers integral to the syndrome, namely carcinoma of the endometrium, ovary, stomach, hepatobiliary system, pancreas, small bowel, brain tumors, and upper uroepithelial tract, these estimates of its frequency are likely to be conservative. The diagnosis is based upon its natural history in concert with a comprehensive cancer family history inclusive of all anatomic sites. In order for surveillance and management to be effective and, indeed, lifesaving, among these high-risk patients, the linchpin to cancer control would be the physician, who must be knowledgeable about hereditary cancer syndromes, their molecular and medical genetics, genetic counseling, and, most importantly, the natural history of the disorders, so that the entirety of this knowledge can be melded to highly-targeted management.     

Familial aggregation of tumors and detection of hereditary non-polyposis colorectal cancer in 3-year experience of 2 population-based colorectal-cancer registries

The clinical data of 2 population-based registries, located in areas with different incidence rates of colorectal cancer, were used in order to assess the role of familial factors in the pathogenesis of these tumors. The occurrence of tumors in family members was investigated in 389 subjects with colorectal cancer registered in Modena (Northern Italy, an area characterized by a high incidence of colorectal malignancies) between 1984 and 1986; similar information was obtained in 213 patients with tumors of the large bowel registered in Ragusa (Sicily, Southern Italy, an area of similar magnitude and with low incidence rates for these tumors) in the 3-year period 1988 to 1990. In both series, colorectal cancer occurred significantly more often among relatives of patients. Controls were patients of the same sex and age (±5 years) hospitalized during the study periods, but not for gastrointestinal or neoplastic diseases. There were 89 cancer cases (3.1%) among 2,851 relatives of patients in Modena, vs. 17 cases among 1,744 relatives (1.0%) in Ragusa (p < 0.01). Apart from colorectal cancer, there was no excess of other types of tumors in patients' families (in both series). During the 3 years of registration, 17 cases of hereditary non-polyposis colorectal cancer (HNPCC, or Lynch syndrome) were diagnosed in Modena; in contrast, this syndrome was more rare in Ragusa (one case only during 3 years of observation). Similarly, many more families with clinical suspicion of HNPCC were recorded in Northern regions (44 vs. 10). Although incidence rates of colorectal cancer are appreciably higher in Northern than in Southern Italian regions, the excess of this cancer type among close relatives is similar. However, fullblown HNPCC or suspected Lynch syndrome were significantly more frequent in Northern Italy. © 1995 Wiley-Liss, Inc.     

Basic concepts for genetic testing in common hereditary colorectal cancer syndromes

Approximately 5% of colorectal cancers are associated with an autosomal dominantly inherited colon cancer syndrome. The two most common familial colon cancer syndromes are hereditary nonpolyposis colorectal cancer (HNPCC), also called Lynch syndrome, and familial adenomatous polyposis (FAP). In many families with these syndromes, the causative mutation can be identified by genetic testing of an affected individual. If an affected individual tests positive for a disease-causing mutation, unaffected, at-risk family members can have genetic testing to determine whether they have inherited the cancer susceptibility mutation, and a personalized cancer surveillance strategy can be adopted. Genetic testing greatly enhances cancer risk assessment in these families; however, the complicated nature of interpretation of the results of gene testing and the emotional impact of the result require that testing be carried out in conjunction with patient education and informed consent by a provider who has a good appreciation for the challenges. This article describes the genetic testing strategy in HNPCC and FAP.