Lynch syndrome: implications for the surgeon

Milestones of Lynch syndrome: 1895-2015

Lynch syndrome, which is now recognized as the most common hereditary colorectal cancer condition, is characterized by the predisposition to a spectrum of cancers, primarily colorectal cancer and endometrial cancer. We chronicle over a century of discoveries that revolutionized the diagnosis and clinical management of Lynch syndrome, beginning in 1895 with Warthin's observations of familial cancer clusters, through the clinical era led by Lynch and the genetic era heralded by the discovery of causative mutations in mismatch repair (MMR) genes, to ongoing challenges.

Histologic evaluation of prophylactic hysterectomy and oophorectomy in Lynch syndrome

Women with Lynch syndrome (LS) are at increased risk for endometrial (EC) and ovarian carcinoma (OC). Current surveillance recommendations for detection of EC and OC in LS patients are not effective. Small studies have shown that prophylactic hysterectomy and bilateral salpingo-oophorectomy (P-TH-BSO) are the most effective and least expensive preventive measures in these patients. Data regarding histologic findings in prophylactic specimens in these patients are lacking. All LS patients who underwent P-TH-BSO at the Memorial Sloan-Kettering Cancer Center from 2000 to 2011 were identified. Slides were evaluated for the presence of endometrial hyperplasia (EH), EC, OC, or any other recurrent histologic findings. Twenty-five patients were identified, with an age range of 36 to 61 years. Fifteen patients had a synchronous or prior colorectal carcinoma, and 2 patients had a history of sebaceous carcinoma. Focal FIGO grade 1 endometrioid ECs were detected in 2 patients; 1 was 54 years of age (MSH2 mutation; superficially invasive), and the other was 56 years of age (MLH1 mutation; noninvasive). Focal complex atypical hyperplasia, unassociated with carcinoma, was seen in 3 patients, ages 35 and 45 (MLH1 mutations) and 53 years (MSH2 mutation). One patient (44 y, with MSH2 mutation) was found to have a mixed endometrioid/clear cell OC and simple EH without atypia. The OC was adherent to the colon but did not show distant metastasis. In our study, P-TH-BSOs performed because of the presence of LS revealed incidental EC and/or EH in 24% of cases and OC in 4%. The ECs were low grade, confined to the endometrium, and seen in patients older than 50 years. Prophylactic hysterectomy allows detection of early lesions in LS; these lesions appear to be small and focal. This small series of prophylactic hysterectomies may provide some clues about LS-associated endometrial carcinogenesis.

Mismatch repair protein expression and colorectal cancer in Hispanics from Puerto Rico

Colorectal cancer (CRC) is a leading cause of morbidity and mortality and alterations in mismatch repair (MMR) genes, leading to absent protein (negative) expression, are responsible for approximately 20% of CRC cases. Immunohistochemistry is a tool for prescreening of MMR protein expression in CRC but the literature on its use on Hispanics is scarce. However, Hispanics represent the second leading ethnicity in the United States (US) and CRC is a public health burden in this group. Our objectives were to determine the frequency of MMR protein-negative CRC and to evaluate its association with clinical and pathological characteristics among Hispanics from Puerto Rico, for the first time to our knowledge. A retrospective observational study of unselected CRC patients from the Puerto Rico Medical Center from 2001 to 2005 was done. MLH1 and MSH2, the most commonly altered MMR genes, protein expression was evaluated using immunohistochemistry, with microsatellite instability (MSI) and BRAF gene analyses in the absence of MLH1 protein expression. One-hundred sixty-four CRC patients were evaluated: the overall MMR protein-negative frequency was 4.3%, with 0.6% frequency of co-occurrence of MLH1-protein negative expression, MSI-high, and normal BRAF gene. MMR protein-negative expression was associated with proximal colon location (P = 0.02) and poor histological tumor differentiation (P = 0.001), but not with other characteristics. The frequency of MMR protein-negative CRC in Hispanics from Puerto Rico was lower than reported in other populations. This finding may explain the lower CRC incidence rate among US Hispanics as compared to US non-Hispanic whites and blacks.

[Our experience with the incidence of hereditary non-polyposis colorectal cancer]

INTRODUCTION

Hereditary Non-Polyposis Colorectal Cancer (HNPCC) is the most frequent genetic disease leading to colorectal malignancies. 3-5 percent of all colorectal cancer cases are related to Hereditary Non-Polyposis Colorectal Cancer. Currently there is no reliable data on the incidence of the disease in Hungary.

METHODS

The family history of 809 patients with colorectal cancer was investigated between 1997 and 2006. Data collection was performed in a retrospective manner in the rst and in a prospective manner in the second phase of the study. Subsequent immunohistochemical and microsatellite instability analysis, and DNA sequencing was carried out to detect any underlying MMR gene mutation. Moreover, multiple ligation dependent probe amplication was applied for recognizing large deletions in MMR genes.

RESULTS

During the investigation 10 pathogenic mutations and several polymorphisms were found. Seven mutations were detected in families fulfilling the Amsterdam Criteria, while the remaining three fulfilled the Bethesda Criteria. In the second phase of the study -- which better reflects the real population characteristics -- six percent of our patients fulfilled completely the Amsterdam Criteria and we managed to nd pathogenic MMR gene mutations in 1,7 percent of our patients.

CONCLUSION

8 out of 10 pathogenic mutations were novel and published rst time by ourselves. No repeatedly occurring mutations were found in our patients. It seems that these genetic alterations are located sporadically on different exons of the involved MMR genes. Our mutation detection rate was 77 percent in the Amsterdam positive patients who were completely examined, which appears to be better than the published data in the relevant literature. Importantly, 30 percent of the mutation carrier could be missed applying only this single criteria system. In order to detect the highest number of HNPCC patients, we suggest using both the Amsterdam as well as the Bethesda Criteria.

ASCO/SSO review of current role of risk-reducing surgery in common hereditary cancer syndromes

BACKGROUND

A significant portion of cancers are accounted for by a heritable component, which has increasingly been linked to mutations in specific genes. Clinical interventions have been formulated for mutation carriers within affected families. The primary interventions for mutation carriers of highly penetrant syndromes are surgical.

METHODS

The American Society of Clinical Oncology and the Society of Surgical Oncology formed a task force charged with presenting an educational symposium on surgical management of hereditary cancer syndromes at annual society meetings, and this resulted in a position paper on this topic. The content of both the symposium and the position paper was developed as a consensus statement.

RESULTS

This article addresses hereditary breast, colorectal, ovarian/endometrial, and multiple endocrine neoplasias. A brief introduction on the genetics and natural history of each disease is provided, followed by detailed descriptions of modern surgical approaches, clinical and genetic indications, timing of prophylactic surgery, and the efficacy of surgery (when known). Although several recent reviews have addressed the role of genetic testing for cancer susceptibility, this article focuses on the issues surrounding surgical technique, timing, and indications for surgical prophylaxis.

CONCLUSIONS

Risk-reducing surgical treatment of hereditary cancer is a complex undertaking. It requires a clear understanding of the natural history of the disease, realistic appreciation of the potential benefits and risks of these procedures in potentially otherwise healthy individuals, and the long-term sequelae of such interventions, as well as the individual patient's and family's perceptions of surgical risk and anticipated benefit.

ASCO/SSO review of current role of risk-reducing surgery in common hereditary cancer syndromes

Although the etiology of solid cancers is multifactorial, with environmental and genetic factors playing a variable role, a significant portion of the burden of cancer is accounted for by a heritable component. Increasingly, the heritable component of cancer predispositions has been linked to mutations in specific genes, and clinical interventions have been formulated for mutation carriers within affected families. The primary interventions for mutations carriers for highly penetrant syndromes such as multiple endocrine neoplasias, familial adenomatous polyposis, hereditary nonpolyposis colon cancer, and hereditary breast and ovarian cancer syndromes are primarily surgical. For that reason, the American Society of Clinical Oncology (ASCO) and the Society of Surgical Oncology (SSO) have undertaken an educational effort within the oncology community. A joint ASCO/SSO Task Force was charged with presenting an educational symposium on the surgical management of hereditary cancer syndromes at the annual ASCO and SSO meetings, resulting in an educational position article on this topic. Both the content of the symposium and the article were developed as a consensus statement by the Task Force, with the intent of summarizing the current standard of care. This article is divided into four sections addressing breast, colorectal, ovarian and endometrial cancers, and multiple endocrine neoplasia. For each, a brief introduction on the genetics and natural history of the disease is provided, followed by a detailed description of modern surgical approaches, including a description of the clinical and genetic indications and timing of prophylactic surgery, and the efficacy of prophylactic surgery when known. Although a number of recent reviews have addressed the role of genetic testing for cancer susceptibility, including the richly illustrated Cancer Genetics and Cancer Predisposition Testing curriculum by the ASCO Cancer Genetics Working Group (available through http://www.asco.org), this article focuses on the issues surrounding the why, how, and when of surgical prophylaxis for inherited forms of cancer. This is a complex process, which requires a clear understanding of the natural history of the disease and variance of penetrance, a realistic appreciation of the potential benefit and risk of a risk-reducing procedure in a potentially otherwise healthy individual, the long-term sequelae of such surgical intervention, as well as the individual patient and family's perception of surgical risk and anticipated benefit.

Pedigree and genetic analysis of a novel mutation carrier patient suffering from hereditary nonpolyposis colorectal cancer

AIM: To screen a suspected Hungarian HNPCC family to find specific mutations and to evaluate their effect on the presentation of the disease.

METHODS: The family was identified by applying the Amsterdam and Bethesda Criteria. Immunohistochemistry was performed, and DNA samples isolated from tumor tissue were evaluated for microsatellite instability. The identification of possible mutations was carried out by sequencing the hMLH1 and hMSH2 genes.

RESULTS: Two different mutations were observed in the index patient and in his family members. The first mutation was located in exon 7, codon 422 of hMSH2, and caused a change from Glu to STOP codon. No other report of such a mutation has been published, as far as we could find in the international databases. The second mutation was found in exon 3 codon 127 of the hMSH2 gene, resulting in Asp→Ser substitution. The second mutation was already published, as a non-pathogenic allelic variation.

CONCLUSION: The pedigree analysis suggested that the newly detected nonsense mutation in exon 7 of the hMSH2 gene might be responsible for the development of colon cancers. In family members where the exon 7 mutation is not coupled with this missense mutation, colon cancer appears after the age of 40. The association of these two mutations seems to decrease the age of manifestation of the disease into the early thirties.

Surgical Implications of Colorectal Cancer Genetics

The applications of genetics in colorectal cancer are not limited to identifying germ-line mutations in genetically predisposed individuals. Reports on the use of molecular genetic markers as prognostic factors and for assessing the response to therapy are common in the literature. As the primary caregiver in the majority of these cases, the surgeon needs a basic knowledge of colorectal genetics and their implications to the patient and the patient's family. This article discusses a practical approach for some of the issues likely to be encountered by the surgeon.

Clinicopathological and molecular genetic analysis of HNPCC in China

AIM: To explore the clinicopathological and molecular genetic features of hereditary nonpolyposis colorectal cancer (HNPCC) in Chinese population.

METHODS: We collected 16 Chinese HNPCC families from Wenzhou, Zhejiang Province, China. Tumor tissues and peripheral white blood cells were studied using microdissection, microsatellite analysis, immunostaining of hMSH2 and hMLH1 proteins and direct DNA sequencing of hMSH2 and hMLH1 genes.

RESULTS: (1) A total of 50 patients had CRC. Average age at diagnosis of the first CRC was 45.7 years; 40.9% and 28.7% of the CRCs were located proximal to the splenic flexure and in the rectum, respectively. Thirty-eight percent of the colorectal cancer patients had synchronous and metachronous CRC. 34.4% and 25% of the CRCs were poor differentiation cancer and mucinous adenocarcinoma, respectively. Fourteen extracoloni tumors were found, and the hepatic cancer was the most common tumor type. Twenty-one patients whose median survival time was 5.7 years died during 1-23 years. Twenty-nine patients have survived for 1-28 years, 58.6%, 41.4% and 24.1% patients have survived for more than 5, 10 and 15 years, respectively; (2) All nine tumor-tissues showed microsatellite instability (MSI) at more than two loci. Four tumor-tissues lost hMSH2 protein expression and one lost hMLH1 protein expression. Three pathological germline mutations were identified from five genetically analyzed families; two of three mutations had not been reported previously as they were a transition from C to A in exon 14 (codon 743) of hMSH2 and a TTC deletion in exon 14 (codon 530) of hMLH1.

CONCLUSION: Chinese HNPCC have specific clinicopathological features, such as early onset, propensity to involve the proximal colon, and high frequency of multiple CRCs, liver cancer more frequent than endometrial cancer. Chinese HNPCC showed relatively frequent germline mutation of mismatch repair (MMR) genes that correlated closely with high-level MSI and loss of expression of MMR genes protein.

Lower incidence of colorectal cancer and later age of disease onset in 27 families with pathogenic MSH6 germline mutations compared with families with MLH1 or MSH2 mutations: the German Hereditary Nonpolyposis Colorectal Cancer Consortium

PURPOSE

The aim of the study was the analysis of the involvement and phenotypic manifestations of MSH6 germline mutations in families suspected of hereditary nonpolyposis colorectal cancer (HNPCC).

PATIENTS AND METHODS

Patients were preselected among 706 families by microsatellite instability, immunohistochemistry, and/or exclusion of MLH1 or MSH2 mutations and were subjected to MSH6 mutation analysis. Clinical and molecular data of MSH6 mutation families were compared with data from families with MLH1 and MSH2 mutations.

RESULTS

We identified 27 families with 24 different pathogenic MSH6 germline mutations, representing 3.8% of the total of the families, and 14.7% of all families with DNA mismatch repair (MMR) gene mutations (n = 183). The median age of onset of colorectal cancer in putative mutation carriers was 10 years higher for MSH6 (54 years; 95% CI, 51 to 56) compared with MLH1 and MSH2 (44 years; 95% CI, 43 to 45; log-rank test, P = .0038). Relative to other malignant tumors, colorectal cancer was less frequent in MSH6 families compared with MLH1 and MSH2 families (Fisher's exact test, P < .001). In contrast, the frequency of non-HNPCC-associated tumors was increased (Fisher's exact test, P < .001).

CONCLUSION

Later age of disease onset and lower incidence of colorectal cancer may contribute to a lower proportion of identified MSH6 mutations in families suspected of HNPCC. However, in approximately half of these families, at least one patient developed colorectal or endometrial cancer in the fourth decade of life. Therefore, a surveillance program as stringent as that for families with MLH1 or MSH2 mutations is recommended.