The PREMM(1,2,6) model predicts risk of MLH1, MSH2, and MSH6 germline mutations based on cancer history

Is it all Lynch syndrome?: An assessment of family history in individuals with mismatch repair-deficient tumors

Background & Aims

Mismatch repair deficient (MMRD) colorectal (CRC) and endometrial (EC) cancers may be suggestive of Lynch syndrome (LS). LS can only be confirmed by positive germline testing. It is unclear if individuals with MMRD tumors but no identifiable cause (MMRD+/germline−) have LS. As LS is hereditary, individuals with LS are expected to have family histories of LS-related tumors. Our study compared the family histories of MMRD+/germline− CRC and/or EC patients to LS CRC and/or EC patients.

Methods

253 individuals with an MMRD CRC or EC from one institution were included in analysis in 1 of 4 groups: LS, MMRD+/germline−, MMRD+/VUS, sporadic MSI-H (MMRD tumor with MLH1 promoter hypermethylation or BRAF mutation). Family histories were analyzed utilizing MMRpro and PREMM_1,2,6. Kruskal-Wallis tests were used to compare family history scores.

Results

MMRD+/germline− individuals had significantly lower median family history scores (MMRpro=8.1, PREMM_1,2,6=7.3) than LS individuals (MMRpro=89.8, PREMM_1,2,6=26.1, p<0.0001).

Conclusion

MMRD+/germline− individuals have less suggestive family histories of LS than individuals with LS. These results imply that MMRD+/germline− individuals may not all have LS. This finding highlights the need to determine other causes of MMRD tumors so that these patients and their families can be accurately counseled regarding screening and management.

Familial colorectal cancer, beyond Lynch syndrome

Although 30% of individuals diagnosed with colorectal cancer (CRC) report a family history of the disease, only 5% to 6% carry germline mutations in genes associated with known hereditary cancer syndromes. The evaluation and management of families affected with CRC can be complicated by variability in disease phenotypes and limited sensitivity of genetic tests. In this review, we examine what is currently known about familial CRC and what we have yet to learn, and explore how novel genomic approaches might be used to identify additional genetic and epigenetic factors implicated in heritable risk for cancer.

History, genetics, and strategies for cancer prevention in Lynch syndrome

Colorectal cancer (CRC) is the most common gastrointestinal malignancy and the third cause of cancer death in men and women in the United States. The majority of CRC cases diagnosed annually are due to sporadic events, but up to 6% are attributed to known monogenic disorders that confer a markedly increased risk for the development of CRC and multiple extracolonic malignancies. Lynch syndrome is the most common inherited CRC syndrome and is associated with mutations in DNA mismatch repair genes, mainly MLH1 and MSH2 but also MSH6, PMS2, and EPCAM. Although the risk of CRC and endometrial cancer may approach near 75% and 50%, respectively, in gene mutation carriers, the identification of these individuals and at-risk family members through predictive genetic testing provides opportunities for cancer prevention including specialized cancer screening, intensified surveillance, and/or prophylactic surgeries. This article will provide a review of the major advances in risk assessment, molecular genetics, DNA mutational analyses, and cancer prevention and management made since Lynch syndrome was first described 100 years ago.

Evaluation of clinical criteria for the identification of Lynch syndrome among unselected patients with endometrial cancer

Clinical criteria, primarily young age of cancer onset and family history of signature cancers, have been developed to identify individuals at elevated risk for Lynch syndrome with the goals of early identification and cancer prevention. In 2007, the Society of Gynecologic Oncology (SGO)-codified criteria for women presenting with gynecologic cancers. These criteria have not been validated in a population-based setting. For 412 unselected endometrial cancers, immunohistochemical expression of DNA mismatch repair proteins and MLH1 methylation were assessed to classify tumors as sporadic or probable Lynch syndrome (PLS). In this cohort, 10.5% of patients were designated as PLS based on tumor testing. The sensitivity and specificity of the SGO criteria to identify these same cases were 32.6% [95% confidence interval (CI), 19.2-48.5] and 77% (95% CI, 72.7-81.8), respectively. With the exception of tumor location in the lower uterine segment, multivariate analysis of clinical features, family history, and pathologic variables failed to identify significant differences between the sporadic and PLS groups. A simplified cost-effectiveness analysis demonstrated that the SGO clinical criteria and universal tissue testing strategies had comparable costs per patient with PLS identified. In conclusion, the SGO criteria successfully identify PLS cases among women with endometrial cancer who are young or have significant family history of signature tumors. However, a larger proportion of patients with PLS who are older and have less significant family history are not detected by this screening strategy. Universal tissue testing may be necessary to capture more individuals at risk for having Lynch syndrome.

Prediction models in Lynch syndrome

Prediction models for the identification of Lynch syndrome have been developed to quantify an individual's risk of carrying a mismatch repair gene mutation and help clinicians decide for whom further risk assessment and genetic testing is necessary. There are diverse clinical settings in which a healthcare provider has the opportunity to assess an individual for Lynch syndrome. Prediction models offer a potentially feasible and useful strategy to systematically identify at-risk individuals, whether they are affected with colorectal cancer or not, and to help with management of the implications of molecular and germline test results. Given the complexity of diagnostic information currently available to clinicians involved in identifying and caring for patients with Lynch syndrome, prediction models provide a useful and complementary aid in medical decision-making. Systematic implementation of prediction models estimates should be considered in routine clinical care and at various stages of cancer risk assessment and prevention. In this manuscript, we review the main prediction models developed for Lynch syndrome, focus on their specific features and performance assessed in several validation studies, compare the models with other clinical and molecular strategies for the diagnosis of Lynch syndrome, and discuss their potential uses in clinical practice.

Risk prediction with machine learning and regression methods

This is a discussion of issues in risk prediction based on the following papers: "Probability estimation with machine learning methods for dichotomous and multicategory outcome: Theory" by Jochen Kruppa, Yufeng Liu, Gérard Biau, Michael Kohler, Inke R. König, James D. Malley, and Andreas Ziegler; and "Probability estimation with machine learning methods for dichotomous and multicategory outcome: Applications" by Jochen Kruppa, Yufeng Liu, Hans-Christian Diener, Theresa Holste, Christian Weimar, Inke R. König, and Andreas Ziegler.

Hereditary colorectal cancer syndromes

SUMMARY Colorectal cancer (CRC) is one of the most common malignancies and the second-leading cause of cancer death in both sexes in developed countries. Over the last 25 years, highly penetrant monogenic germline mutations that predispose to CRC and other digestive tumors have been identified, accounting for up to 5% of all CRC cases. Identification and characterization of these disorders have allowed modification of their natural history, with a substantial decrease in morbidity and mortality among high-risk patients. Recognizing hereditary CRC has also impacted predictive genetic testing and personalized medicine based on genomic information. This review summarizes the current knowledge on hereditary CRC regarding pathogenesis, clinical features, diagnostic evaluation and management recommendations.

Easy-to-use online referral test detects most patients with a high familial risk of colorectal cancer

AIM

Currently only 12-30% of individuals with a high risk of Lynch syndrome, the most common hereditary colorectal cancer (CRC) syndrome, are referred for genetic counselling. We assessed the sensitivity, usability and user experiences of a new online referral test aimed at improving referral of high-risk individuals for genetic counselling.

METHOD

Sensitivity was assessed by entering pedigree data from high-risk individuals (i.e. Lynch syndrome mutation carriers) into the referral test to determine whether genetic counselling was recommended. For usability, we assessed nonmedical staff members' ability to determine referral, according to guidelines, in seven fictive clinical cases using the referral test after minimal training. Real-life users answered questions about their experience with the referral test.

RESULT

Sensitivity of the referral test was 91% for mutation carriers with CRC (n = 164) and 73% for all affected and nonaffected mutation carriers (n = 420). Nonmedical staff members (n = 20) determined referral according to guidelines in 84% of cases using the referral test. Ten per cent (256/2470) of real-life users provided feedback about experiences; of those, 71% reported that the referral test increased reassurance, certainty about their familial risk and/or certainty about referral.

CONCLUSION

The referral test has a high sensitivity in detecting individuals with a high risk of Lynch syndrome and is suitable for use in clinical practice. Widespread use of the referral test should improve cancer prevention in high-risk patients and their relatives.

UK colorectal cancer patients are inadequately assessed for Lynch syndrome

OBJECTIVE

To establish whether colorectal cancer patients in two centres in the UK are screened appropriately for Lynch syndrome, in accordance with current international guidance.

DESIGN

Patients newly diagnosed with colorectal cancer over an 18-month period were identified from the UK National Bowel Cancer Audit Programme. Their records and management were reviewed retrospectively.

SETTING

Two university teaching hospitals, Imperial College Healthcare and Oxford Radcliffe Hospitals NHS Trusts.

OUTCOMES MEASURED

Whether patients were screened for Lynch syndrome-and the outcome of that evaluation, if it took place-were assessed from patients' clinical records. The age, tumour location and family history of screened patients were compared to those of unscreened patients.

RESULTS

Five hundred and fifty three patients with newly diagnosed colorectal cancer were identified. Of these, 97 (17.5%) satisfied the revised Bethesda criteria, and should have undergone further assessment. There was no evidence that those guidelines had been contemporaneously applied to any patient. In practice, only 22 of the 97 (22.7%) eligible patients underwent evaluation. The results for 14 of those 22 (63.6%) supported a diagnosis of Lynch syndrome, but only nine of the 14 (64.3%) were referred for formal mismatch repair gene testing. No factors reliably predicted whether or not a patient would undergo Lynch syndrome screening.

CONCLUSIONS

Colorectal teams in the UK do not follow international guidance identifying the patients who should be screened for Lynch syndrome. Patients and their families are consequently excluded from programmes reducing colorectal cancer incidence and mortality. Multidisciplinary teams should work with their local genetics services to develop reliable algorithms for patient screening and referral.

Familial pancreatic cancer: genetic advances

Beset by poor prognosis, pancreatic ductal adenocarcinoma is classified as familial or sporadic. This review elaborates on the known genetic syndromes that underlie familial pancreatic cancer, where there are opportunities for genetic counseling and testing as well as clinical monitoring of at-risk patients. Such subsets of familial pancreatic cancer involve germline cationic trypsinogen or PRSS1 mutations (hereditary pancreatitis), BRCA2 mutations (usually in association with hereditary breast-ovarian cancer syndrome), CDKN2 mutations (familial atypical mole and multiple melanoma), or DNA repair gene mutations (e.g., ATM and PALB2, apart from those in BRCA2). However, the vast majority of familial pancreatic cancer cases have yet to have their genetic underpinnings elucidated, waiting in part for the results of deep sequencing efforts.

Hereditary cancer risk assessment: essential tools for a better approach

Hereditary cancer risk assessment (HCRA) is a multidisciplinary process of estimating probabilities of germline mutations in cancer susceptibility genes and assessing empiric risks of cancer, based on personal and family history. It includes genetic counseling, testing and management of at-risk individuals so that they can make well-informed choices about cancer surveillance, surgical treatment and chemopreventive measures, including biomolecular cancer therapies. Providing patients and family members with an appropriate HCRA will contribute to a better process of making decisions about their personal and family risks of cancer. Following individuals at high risk through screening protocols, reassuring those at low risk, and referring those at increased risk of hereditary cancer to a cancer genetics center may be the best suitable approach of HCRA.

Current and future role of MR enterography in the management of Crohn disease

OBJECTIVE

The purpose of this article is to explore the future role of MRI in assessing the global disease burden of Crohn disease and monitoring treatment response.

CONCLUSION

MR enterography is increasingly used to evaluate disease activity in Crohn disease, and scoring methods have been validated. Current MRI protocols may be extended to allow the assessment of inflammation and fibrosis.

Collaborative cancer epidemiology in the 21st century: the model of cancer consortia

During the last two decades, epidemiology has undergone a rapid evolution toward collaborative research. The proliferation of multi-institutional, interdisciplinary consortia has acquired particular prominence in cancer research. Herein, we describe the characteristics of a network of 49 established cancer epidemiology consortia (CEC) currently supported by the Epidemiology and Genomics Research Program (EGRP) at the National Cancer Institute (NCI). This collection represents the largest disease-based research network for collaborative cancer research established in population sciences. We describe the funding trends, geographic distribution, and areas of research focus. The CEC have been partially supported by 201 grants and yielded 3,876 publications between 1995 and 2011. We describe this output in terms of interdisciplinary collaboration and translational evolution. We discuss challenges and future opportunities in the establishment and conduct of large-scale team science within the framework of CEC, review future prospects for this approach to large-scale, interdisciplinary cancer research, and describe a model for the evolution of an integrated Network of Cancer Consortia optimally suited to address and support 21st-century epidemiology.

Genetic testing strategies in newly diagnosed endometrial cancer patients aimed at reducing morbidity or mortality from lynch syndrome in the index case or her relatives

Endometrial cancer is the first malignancy in 50% of women with Lynch syndrome, an autosomal dominant cancer-prone syndrome caused by germline mutations in genes encoding components of the DNA mismatch repair (MMR) pathway. These women (2-4% of all those with endometrial cancer) are at risk of metachronous colorectal cancer and other Lynch syndrome-associated cancers, and their first-degree relatives are at 50% risk of Lynch syndrome. Testing all women newly diagnosed with endometrial cancer for Lynch syndrome may have clinical utility for the index case and her relatives by alerting them to the benefits of surveillance and preventive options, primarily for colorectal cancer. The strategy involves offering germline DNA mutation testing to those whose tumour shows loss-of-function of MMR protein(s) when analysed for microsatellite instability (MSI) and/or by immunohistochemisty (IHC). In endometrial tumours from unselected patients, MSI and IHC have a sensitivity of 80-100% and specificity of 60-80% for detecting a mutation in an MMR gene, though the number of suitable studies for determining clinical validity is small. The clinical validity of strategies to exclude those with false-positive tumour test results due to somatic hypermethylation of the MLH1 gene promoter has not been determined. Options include direct methylation testing, and excluding those over the age of 60 who have no concerning family history or clinical features. The clinical utility of Lynch syndrome testing for the index case depends on her age and the MMR gene mutated: the net benefit is lower for those diagnosed at older ages and with less-penetrant MSH6 mutations. To date, women with these features are the majority of those diagnosed through screening unselected endometrial cancer patients but the number of studies is small. Similarly, clinical utility to relatives of the index case is higher if the family's mutation is in MLH1 or MSH2 than for MSH6 or PMS2. Gaps in current evidence include a need for large, prospective studies on unselected endometrial cancer patients, and for health-economic analysis based on appropriate assumptions.

PTEN germline mutations in patients initially tested for other hereditary cancer syndromes: would use of risk assessment tools reduce genetic testing?

PURPOSE

PTEN Hamartoma Tumor syndrome (PHTS) includes patients with Cowden syndrome or other syndromes with germline mutation of the PTEN tumor suppressor gene. The risk for breast, colorectal, and endometrial cancer and polyposis is increased, creating clinical overlap with hereditary breast and ovarian cancer (HBOC), Lynch syndrome (LS), and adenomatous polyposis syndromes (APS). We reviewed our series of patients with PHTS to determine how often testing criteria for these syndromes were met and how often other-gene testing was ordered before testing PTEN.

PATIENTS AND METHODS

Patients were prospectively recruited by relaxed International Cowden Consortium criteria or presence of known germline PTEN mutation. Mutations were identified by mutation scanning/multiplex ligation-dependent probe amplification analysis and confirmed by sequencing/quantitative polymerase chain reaction. Patients were excluded if they were adopted, were <18 years of age, or if they were diagnosed with Cowden syndrome before 1998. Standard risk-assessment models were applied to determine whether patients met HBOC testing criteria, LS-relevant Amsterdam II/Bethesda 2004 criteria, or had adenomatous polyps. Prior probability of PTEN mutation was estimated with the Cleveland Clinic PTEN risk calculator.

RESULTS

Of 137 PTEN mutation-positive adult probands, 59 (43.1%) met testing criteria for HBOC or LS. Of these, 45 (32.8%) were first offered HBOC, LS, or APS testing. Of those who underwent APS testing, none of the six patients met criteria. Initial risk assessment by a genetics specialist was significantly associated with immediate PTEN testing in patients also meeting HBOC testing criteria. Using this PTEN risk assessment tool could have spared gene testing for 22 unlikely syndromes, at a total cost of $66,080.

CONCLUSION

PHTS is an important differential diagnosis for patients referred for HBOC, LS, or APS. Risk assessment tools may help focus genetic analysis and aid in the interpretation of multiplex testing.

Criteria and prediction models for mismatch repair gene mutations: a review

One of the strongest predictors of colorectal cancer risk is carrying a germline mutation in a DNA mismatch repair (MMR) gene. Once identified, mutation carriers can be recommended for intensive screening that will substantially reduce their high colorectal cancer risk. Conversely, the relatives of carriers identified as non-carriers can be relieved of the burden of intensive screening. Criteria and prediction models that identify likely mutation carriers are needed for cost-effective, targeted, germline testing for MMR gene mutation. We reviewed 12 criteria/guidelines and 8 prediction models (Leiden, Amsterdam-plus, Amsterdam-alternative, MMRpro, PREMM1,2,6, MMRpredict, Associazione Italiana per lo studio della Familiarità ed Ereditarietà dei tumori Gastrointestinali (AIFEG) and the Myriad Genetics Prevalence table) for identifying mutation carriers. While criteria are only used to identify individuals with colorectal cancer (yes/no for screening followed by germline testing), all prediction models except MMRpredict and Myriad tables can predict the probability of carrying mutations for individuals with or without colorectal cancer. We conducted a meta-analysis of the discrimination performance of 17 studies that validated the prediction models. The pooled estimate for the area under curve was 0.80 (95% CI 0.72 to 0.88) for MMRpro, 0.81 (95% CI 0.73 to 0.88) for MMRpredict, 0.84 (95% CI 0.81 to 0.88) for PREMM, and 0.85 (95% CI 0.78 to 0.91) for Leiden model. Given the high degree of overlap in the CIs, we cannot state that one model has a higher discrimination than any of the others. Overall, the existing statistical models have been shown to be sensitive and specific (at a 5% cut-off) in predicting MMR gene mutation carriers. Future models may need to: provide prediction of PMS2 mutations, take into account a wider range of Lynch syndrome-associated cancers when assessing family history, and be applicable to all people irrespective of any cancer diagnosis.

Imaging indexes of activity and severity for Crohn's disease: current status and future trends

BACKGROUND

Cross-sectional imaging techniques, including ultrasonography (US), computed tomography (CT), and magnetic resonance imaging (MRI) are increasingly used for evaluation of Crohn's disease (CD).

AIM

To review the accuracy of cross-sectional imaging indexes for measurement of disease activity and severity in patients with CD, and to evaluate its applicability on daily clinical practice and research.

METHODS

Relevant publications were identified by literature search, and selected based on predefined quality parameters, including a sample size and reference standard. Nineteen publications were chosen.

RESULTS

The US-based indexes of activity showed high correlation with reference standard indexes. There is a good or very good agreement between the MR-based indexes and the reference standard when the comparison is limited to small segments of intestine. Significant discrepancies have been found between indexes that evaluate the colon. Only one CT-based index was included. The main strengths and weaknesses of the indexes, according to its design, are discussed.

CONCLUSION

Standardization of image acquisition protocols and patient preparation should be procured, especially for MRI. In daily practice, a simple, semi-quantitative index providing relevant information on disease activity and severity is preferable. For research purposes, a precise and reproducible index should be mandatory.

Underutilization of Lynch syndrome screening in a multisite study of patients with colorectal cancer

PURPOSE

The aim of this study was to examine Lynch syndrome screening of patients with metastatic colorectal cancer in integrated health-care-delivery organizations.

METHODS

We determined the availability of Lynch syndrome screening criteria and actual Lynch syndrome screening in the medical records of 1,188 patients diagnosed with metastatic colorectal cancer between 2004 and 2009 at seven institutions in the Cancer Research Network.

RESULTS

We found infrequent use of Lynch syndrome screening (41/1,188). Family history was available for 937 of the 1,188 patients (79%). There was sufficient information to assess Lynch syndrome risk using family history-based criteria in 719 of the 937 patients (77%) with family history documentation. In 391 individuals with a family history of a Lynch syndrome-associated cancer, 107 (27%) could not be evaluated due to missing information such as age of cancer onset. Eleven percent of patients who met the Bethesda criteria and 25% of individuals who met the Amsterdam II criteria were screened for Lynch syndrome. Recommended guidelines were adhered to during screening, but no testing method was preferred.

CONCLUSION

The information required for Lynch syndrome screening decisions is routinely collected but seldom used. There is a critical gap between collection of family history and its use to guide Lynch syndrome screening, which may support a case for implementation of universal screening guidelines.

Recording of family history is associated with colorectal cancer stage

BACKGROUND

Colorectal cancer (CRC) associated with Lynch syndrome usually presents at a relatively young age. The Revised Bethesda Guidelines advise screening for Lynch syndrome in patients diagnosed with CRC and a positive family history (FH) of CRC and other Lynch-related cancers.

OBJECTIVE

To evaluate recording of the FH and identify factors associated with recording in young patients with CRC.

PATIENTS AND METHODS

In one academic and two nonacademic hospitals, of all patients diagnosed with CRC at the age of 60 years or younger between 1999 and 2007, electronic medical records were evaluated for a recorded FH of CRC and other Lynch-related cancers. Patient and tumor characteristics were retrieved from the Dutch Comprehensive Cancer Centre and the Dutch Pathological Archive.

RESULTS

A total of 676 patients were identified. FH was recorded in 395/676 (58%) patients. From 1999 to 2007, recording improved with an odds ratio (OR) of 1.10 [95% confidence interval (CI) 1.03-1.17] per year. Stage III CRC (OR 1.71, 95% CI 1.07-2.75) and administration of chemotherapy (OR 1.84, 95% CI 1.17-2.89) were associated with recording in multivariate analysis. Other factors, including age at diagnosis, sex, surgery, radiotherapy, proximal tumor localization, poor differentiation, and mucinous histology, were not associated with recording.

CONCLUSION

A FH of CRC and other Lynch-related cancers was not recorded in ∼40% of young CRC patients and recording improved only slightly over the years. As a first step in the identification of Lynch-related cancer families, physicians should be trained to record a detailed FH in the work-up of all newly diagnosed CRC patients.

Familial colon cancer syndromes: an update of a rapidly evolving field

Colorectal cancer (CRC) is a major cause of morbidity and mortality in the world. Up to 30 % of CRCs have evidence of a familial component, and about 5 % are thought to be due to well-characterized inherited mutations. This review will focus on recent developments in the understanding of the individual hereditary CRC syndromes, including Lynch syndrome, familial CRC type X, familial adenomatous polyposis, MutYH-associated polyposis, Peutz-Jeghers syndrome, juvenile polyposis syndrome, PTEN hamartomatous syndrome, and serrated polyposis syndrome. Advances within the area of hereditary colon cancer syndromes paint a picture of a rapidly moving, rapidly maturing, and increasingly collaborative field with many opportunities for ongoing research and development.

Comparison of the clinical prediction model PREMM(1,2,6) and molecular testing for the systematic identification of Lynch syndrome in colorectal cancer

BACKGROUND

Lynch syndrome is caused by germline mismatch repair (MMR) gene mutations. The PREMM(1,2,6) model predicts the likelihood of a MMR gene mutation based on personal and family cancer history.

OBJECTIVE

To compare strategies using PREMM(1,2,6) and tumour testing (microsatellite instability (MSI) and/or immunohistochemistry (IHC) staining) to identify mutation carriers.

DESIGN

Data from population-based or clinic-based patients with colorectal cancers enrolled through the Colon Cancer Family Registry were analysed. Evaluation included MSI, IHC and germline mutation analysis for MLH1, MSH2, MSH6 and PMS2. Personal and family cancer histories were used to calculate PREMM(1,2,6) predictions. Discriminative ability to identify carriers from non-carriers using the area under the receiver operating characteristic curve (AUC) was assessed. Predictions were based on logistic regression models for (1) cancer assessment using PREMM(1,2,6), (2) MSI, (3) IHC for loss of any MMR protein expression, (4) MSI+IHC, (5) PREMM(1,2,6)+MSI, (6) PREMM(1,2,6)+IHC, (7) PREMM(1,2,6)+IHC+MSI.

RESULTS

Among 1651 subjects, 239 (14%) had mutations (90 MLH1, 125 MSH2, 24 MSH6). PREMM(1,2,6) discriminated well with AUC 0.90 (95% CI 0.88 to 0.92). MSI alone, IHC alone, or MSI+IHC each had lower AUCs: 0.77, 0.82 and 0.82, respectively. The added value of IHC+PREMM(1,2,6) was slightly greater than PREMM(1,2,6)+MSI (AUC 0.94 vs 0.93). Adding MSI to PREMM(1,2,6)+IHC did not improve discrimination.

CONCLUSION

PREMM(1,2,6) and IHC showed excellent performance in distinguishing mutation carriers from non-carriers and performed best when combined. MSI may have a greater role in distinguishing Lynch syndrome from other familial colorectal cancer subtypes among cases with high PREMM(1,2,6) scores where genetic evaluation does not disclose a MMR mutation.

Identification of Lynch syndrome among patients with colorectal cancer

CONTEXT

Lynch syndrome is the most common form of hereditary colorectal cancer (CRC) and is caused by germline mutations in DNA mismatch repair (MMR) genes. Identification of gene carriers currently relies on germline analysis in patients with MMR-deficient tumors, but criteria to select individuals in whom tumor MMR testing should be performed are unclear.

OBJECTIVE

To establish a highly sensitive and efficient strategy for the identification of MMR gene mutation carriers among CRC probands.

DESIGN, SETTING, AND PATIENTS

Pooled-data analysis of 4 large cohorts of newly diagnosed CRC probands recruited between 1994 and 2010 (n = 10,206) from the Colon Cancer Family Registry, the EPICOLON project, the Ohio State University, and the University of Helsinki examining personal, tumor-related, and family characteristics, as well as microsatellite instability, tumor MMR immunostaining, and germline MMR mutational status data.

MAIN OUTCOME

Performance characteristics of selected strategies (Bethesda guidelines, Jerusalem recommendations, and those derived from a bivariate/multivariate analysis of variables associated with Lynch syndrome) were compared with tumor MMR testing of all CRC patients (universal screening).

RESULTS

Of 10,206 informative, unrelated CRC probands, 312 (3.1%) were MMR gene mutation carriers. In the population-based cohorts (n = 3671 probands), the universal screening approach (sensitivity, 100%; 95% CI, 99.3%-100%; specificity, 93.0%; 95% CI, 92.0%-93.7%; diagnostic yield, 2.2%; 95% CI, 1.7%-2.7%) was superior to the use of Bethesda guidelines (sensitivity, 87.8%; 95% CI, 78.9%-93.2%; specificity, 97.5%; 95% CI, 96.9%-98.0%; diagnostic yield, 2.0%; 95% CI, 1.5%-2.4%; P < .001), Jerusalem recommendations (sensitivity, 85.4%; 95% CI, 77.1%-93.6%; specificity, 96.7%; 95% CI, 96.0%-97.2%; diagnostic yield, 1.9%; 95% CI, 1.4%-2.3%; P < .001), and a selective strategy based on tumor MMR testing of cases with CRC diagnosed at age 70 years or younger and in older patients fulfilling the Bethesda guidelines (sensitivity, 95.1%; 95% CI, 89.8%-99.0%; specificity, 95.5%; 95% CI, 94.7%-96.1%; diagnostic yield, 2.1%; 95% CI, 1.6%-2.6%; P < .001). This selective strategy missed 4.9% of Lynch syndrome cases but resulted in 34.8% fewer cases requiring tumor MMR testing and 28.6% fewer cases undergoing germline mutational analysis than the universal approach.

CONCLUSION

Universal tumor MMR testing among CRC probands had a greater sensitivity for the identification of Lynch syndrome compared with multiple alternative strategies, although the increase in the diagnostic yield was modest.

A high degree of LINE-1 hypomethylation is a unique feature of early-onset colorectal cancer

OBJECTIVE

Early-onset colorectal cancer (CRC) represents a clinically distinct form of CRC that is often associated with a poor prognosis. Methylation levels of genomic repeats such as LINE-1 elements have been recognized as independent factors for increased cancer-related mortality. The methylation status of LINE-1 elements in early-onset CRC has not been analyzed previously.

DESIGN

We analyzed 343 CRC tissues and 32 normal colonic mucosa samples, including 2 independent cohorts of CRC diagnosed ≤ 50 years old (n=188), a group of sporadic CRC >50 years (MSS n=89; MSI n=46), and a group of Lynch syndrome CRCs (n=20). Tumor mismatch repair protein expression, microsatellite instability status, LINE-1 and MLH1 methylation, somatic BRAF V600E mutation, and germline MUTYH mutations were evaluated.

RESULTS

Mean LINE-1 methylation levels (± SD) in the five study groups were early-onset CRC, 56.6% (8.6); sporadic MSI, 67.1% (5.5); sporadic MSS, 65.1% (6.3); Lynch syndrome, 66.3% (4.5) and normal mucosa, 76.5% (1.5). Early-onset CRC had significantly lower LINE-1 methylation than any other group (p<0.0001). Compared to patients with <65% LINE-1 methylation in tumors, those with ≥ 65% LINE-1 methylation had significantly better overall survival (p=0.026, log rank test).

CONCLUSIONS

LINE-1 hypomethylation constitutes a potentially important feature of early-onset CRC, and suggests a distinct molecular subtype. Further studies are needed to assess the potential of LINE-1 methylation status as a prognostic biomarker for young people with CRC.

Influence of patient preferences on the cost-effectiveness of screening for lynch syndrome

PURPOSE

Patients and relatives have varying preferences for genetic testing and interventions related to hereditary cancer syndromes. We examined how the impact of these services on quality of life (QoL) affects the cost-effectiveness of screening for Lynch syndrome among probands newly diagnosed with colorectal cancer and their relatives.

METHODS

We constructed a state-transition model comparing screening strategies (clinical criteria, prediction algorithms, tumor testing, and upfront germline testing) with no screening to identify Lynch syndrome. The model incorporated individuals' health state utilities after screening, germline testing, and risk-reducing surgeries, with utilities persisting for 12 months in the base case. Outcomes consisted of quality-adjusted life-years (QALYs), costs, and cost per QALY gained. Sensitivity analyses assessed how the duration and magnitude of changes in QoL influenced results.

RESULTS

Multiple screening strategies yielded gains in QALYs at acceptable costs compared with no screening. The preferred strategy-immunohistochemistry of tumors followed by BRAF mutation testing (IHC/BRAF)-cost $59,700 per QALY gained in the base case. The duration and magnitude of decreases in QoL after decisions related to germline testing and surgeries were key determinants of the cost-effectiveness of screening. IHC/BRAF cost > $100,000 per QALY gained when decrements to QoL persisted for 21 months.

CONCLUSION

Screening for Lynch syndrome in the population is likely to yield long-term gains in life expectancy that outweigh any short-term decreases in QoL, at acceptable costs. Counseling for individuals should aim to mitigate potential negative impact of genetic testing and risk-reducing interventions on QoL.

Diagnosing Lynch syndrome: more light at the end of the tunnel

Since the recognition of Lynch syndrome, which confers a high risk of colorectal, uterine, and other cancers, approaches to its diagnosis have included a family history of associated cancers and web-based algorithms. Identification of causative genes now allows a precise diagnosis, thus focusing present efforts on who should have genetic testing. Testing for cancer tissue changes can determine who should have germline genetic testing. Indeed, such tumor testing is now generally recommended for all newly diagnosed colorectal cancer cases. As reported in this issue of the journal by Yurgelun and colleagues (beginning on page 574), large colorectal adenomatous polyps (≥10 mm) from patients with Lynch syndrome exhibit findings similar to those in Lynch syndrome colorectal cancer tissues. This finding indicates that testing larger adenomas in persons at a significant risk for Lynch syndrome can now determine the need for germline genetic testing. Although further study is needed for general application, the present study justifies large polyp testing in high-risk families when cancer tissue is unavailable, albeit negative polyp tissue would not rule out Lynch syndrome, as would negative cancer tissue.

Extending the c-statistic to nominal polytomous outcomes: the Polytomous Discrimination Index

Diagnostic problems in medicine are sometimes polytomous, meaning that the outcome has more than two distinct categories. For example, ovarian tumors can be benign, borderline, primary invasive, or metastatic. Extending the main measure of binary discrimination, the c-statistic or area under the ROC curve, to nominal polytomous settings is not straightforward. This paper reviews existing measures and presents the polytomous discrimination index (PDI) as an alternative. The PDI assesses all sets of k cases consisting of one case from each outcome category. For each category i (i = 1, … ,k), it is assessed whether the risk of category i is highest for the case from category i. A score of 1∕k is given per category for which this holds, yielding a set score between 0 and 1 to indicate the level of discrimination. The PDI is the average set score and is interpreted as the probability to correctly identify a case from a randomly selected category within a set of k cases. This probability can be split up by outcome category, yielding k category-specific values that result in the PDI when averaged. We demonstrate the measures on two diagnostic problems (residual mass histology after chemotherapy for testicular cancer; diagnosis of ovarian tumors). We compare the behavior of the measures on theoretical data, showing that PDI is more strongly influenced by simultaneous discrimination between all categories than by partial discrimination between pairs of categories. In conclusion, the PDI is attractive because it better matches the requirements of a measure to summarize polytomous discrimination.

Inherited colorectal cancer syndromes

Colorectal cancer is the most common gastrointestinal malignancy and the second leading cause of cancer death in both men and women in the United States. Most colorectal cancer cases diagnosed annually are due to sporadic events, but up to 5% are attributed to known monogenic disorders including Lynch syndrome, familial adenomatous polyposis, MYH-associated polyposis, and the rare hamartomatous polyposis syndromes. These inherited colorectal cancer syndromes confer a markedly increased risk for the development of multiple cancers, and predictive genetic testing is available to identify mutation carriers and at-risk family members. Through personalized strategies for diagnosis and management, a substantial reduction in morbidity and mortality has been appreciated among patients at highest risk for the development of colorectal cancer.

[Coexistence of Peutz-Jeghers' syndrome and Lynch's syndrome in the same patient]

Peutz-Jeghers' syndrome is an uncommon polyposis syndrome characterized by the presence of hamartomatous polyps in the gastrointestinal tract and mucocutaneous pigmentation (especially in the oral-nasal and perianal areas and hands and feet). Inheritance is autosomal dominant, caused by a germline mutation in the STK11 (LKB1) gene. The risk of breast and gastrointestinal cancer is increased in this syndrome. Lynch's syndrome is also known as hereditary non-polyposis colorectal cancer. This syndrome is caused by a mutation in DNA mismatch repair genes and increases the risk of colon and endometrial cancer, as well as that of other neoplasms (ovary, upper urological tract, gastric, small intestine, pancreas, skin and brain). We present the case of a young woman with colorectal cancer and the coexistence of both syndromes. This association has not previously been reported in the literature.

Performance of PREMM(1,2,6), MMRpredict, and MMRpro in detecting Lynch syndrome among endometrial cancer cases

PURPOSE

Lynch syndrome accounts for 2-5% of endometrial cancer cases. Lynch syndrome prediction models have not been evaluated among endometrial cancer cases.

METHODS

Area under the receiver operating curve (AUC), sensitivity and specificity of PREMM(1,2,6), MMRpredict, and MMRpro scores were assessed among 563 population-based and 129 clinic-based endometrial cancer cases.

RESULTS

A total of 14 (3%) population-based and 80 (62%) clinic-based subjects had pathogenic mutations. PREMM(1,2,6), MMRpredict, and MMRpro were able to distinguish mutation carriers from noncarriers (AUC of 0.77, 0.76, and 0.77, respectively), among population-based cases. All three models had lower discrimination for the clinic-based cohort, with AUCs of 0.67, 0.64, and 0.54, respectively. Using a 5% cutoff, sensitivity and specificity were as follows: PREMM(1,2,6), 93% and 5% among population-based cases and 99% and 2% among clinic-based cases; MMRpredict, 71% and 64% for the population-based cohort and 91% and 0% for the clinic-based cohort; and MMRpro, 57% and 85% among population-based cases and 95% and 10% among clinic-based cases.

CONCLUSION

Currently available prediction models have limited clinical utility in determining which patients with endometrial cancer should undergo genetic testing for Lynch syndrome. Immunohistochemical analysis and microsatellite instability testing may be the best currently available tools to screen for Lynch syndrome in endometrial cancer patients.

Yield of routine molecular analyses in colorectal cancer patients ≤70 years to detect underlying Lynch syndrome

Although early detection of Lynch syndrome (LS) is important, a considerable proportion of patients with LS remains unrecognized. We aimed to study the yield of LS detection by routine molecular analyses in colorectal cancer (CRC) patients until 70 years of age. We prospectively included consecutive CRC patients ≤70 years. Tumour specimens were analysed for microsatellite instability (MSI), immunohistochemical mismatch-repair protein expression and MLH1-promoter methylation. Tumours were classified as either: (a) likely caused by LS; (b) sporadic microsatellite-unstable (MSI-H); or (c) microsatellite-stable (MSS). Predictors of LS were determined by multivariable logistic regression. A total of 1117 CRC patients (57% males, median age 61 years) were included. Fifty patients (4.5%, 95% CI 3.4-5.9) were likely to have LS, and 71 had a sporadic MSI-H tumour (6.4%, 95% CI 5.1-8.0). Thirty-five patients likely to have LS (70%) were aged > 50 years. A molecular profile compatible with LS was detected in 10% (15/144) of patients aged ≤50, in 4% (15/377) of those aged 51-60 and in 3% (20/596) of patients > 61 years. Compared to MSS cases, patients likely to have LS were significantly younger (OR 3.9, 95% CI 1.7-8.7) and more often had right-sided CRCs (OR 14, 95% CI 6.0-34). In conclusion, molecular screening for LS in CRC patients ≤70 years leads to identification of a molecular profile compatible with LS in 4.5% of patients, with most of them not fulfilling the age criterion (≤50 years) routinely used for LS assessment. Routine use of MSI testing may be considered in CRC patients up to the age of 70 years, with a central role for the pathologist in the selection of patients.

Identification and surveillance of 19 Lynch syndrome families in southern Italy: report of six novel germline mutations and a common founder mutation

Lynch syndrome (LS), or hereditary non-polyposis colorectal cancer (HNPCC), is an autosomal dominant condition responsible for early onset cancer mostly in the colonrectum and endometrium as well as in other organ sites. Lynch syndrome is caused by germline mutations in mismatch repair genes, prevalently in hMSH2, hMLH1, and less frequently in hMSH6 and hPMS2. Twenty-nine non-related index cases with colorectal cancer (CRC) were collected from a region in southeast Italy (Apulia). Among this set of patients, fifteen fulfilled the Amsterdam criteria II. The presence of tumor microsatellite instability (MSI) was assessed in all index cases and 19 (15 AC+/4 AC-) were classified as MSI-H. Mutation analysis performed on all patients, identified 15 pathogenic mutations in hMLH1 and 4 in hMSH2. 4/15 mutations in hMLH1 and 2/4 hMSH2 mutations have not been previously reported. Three previously reported mutations were further investigated for the possibility of a common founder effect. Genetic counseling was offered to all probands and extended to 183 relatives after molecular testing and 85 (46%) mutation carriers were identified. Eighty mutation carriers underwent an accurate clinical and instrumental surveillance protocol. Our results confirm that the identification of LS patients based exclusively on family history may miss patients carrying germline mutations in the MMR genes. Moreover, our results demonstrated that molecular screening and subsequent instrumental surveillance are very effective in identifying CRCs at earlier stages and reducing the number of deaths from secondary cancers in HNPCC patients.

Performance of Lynch syndrome predictive models in a multi-center US referral population

OBJECTIVES

Lynch syndrome is the most common cause of inherited colorectal cancer (CRC) and is due to germline mutations in mismatch repair (MMR) genes. Early Lynch syndrome diagnosis and appropriate CRC surveillance improves mortality. Traditional qualitative clinical criteria including Amsterdam and Bethesda guidelines may miss mutation carriers. Recently, quantitative predictive models including MMRPredict, PREMM(1,2,6), and MMRPro were developed to facilitate diagnosis. However, these models remain to be externally validated in the United States. Therefore, we evaluated the test characteristics of Lynch syndrome predictive models in a tertiary referral group at two US academic centers.

METHODS

We retrospectively collected data on 230 consecutive individuals who underwent genetic testing for MMR gene mutations at the University of Chicago and University of California at San Francisco's Cancer Risk Clinics. Each individual's risk of mutation was examined using MMRPredict, PREMM(1,2,6), and MMRPro. Amsterdam and Bethesda criteria were also determined. Testing characteristics were calculated for each of the models.

RESULTS

We included 230 individuals in the combined cohort. In all, 113 (49%) probands were MMR mutation carriers. Areas under the receiver operator characteristic curves were 0.76, 0.78, and 0.82 for MMRPredict, PREMM(1,2,6), and MMRPro, respectively. While similar in overall performance, our study highlights unique test characteristics of these three quantitative models including comparisons of sensitivity and specificity. Moreover, we identify characteristics of mutation carriers who were missed by each model.

CONCLUSIONS

Overall, all three Lynch syndrome predictive models performed comparably in our multi-center US referral population. These results suggest that Lynch syndrome predictive models can be used to screen for MMR mutation carriers and can provide improved test characteristics compared with traditional clinical criteria. Identification of MMR mutation carriers is paramount as appropriate screening can prevent CRC mortality in this high-risk group.

Strategies to identify the Lynch syndrome among patients with colorectal cancer: a cost-effectiveness analysis

BACKGROUND

Testing has been advocated for all persons with newly diagnosed colorectal cancer to identify families with the Lynch syndrome, an autosomal dominant cancer-predisposition syndrome that is a paradigm for personalized medicine.

OBJECTIVE

To estimate the effectiveness and cost-effectiveness of strategies to identify the Lynch syndrome, with attention to sex, age at screening, and differential effects for probands and relatives.

DESIGN

Markov model that incorporated risk for colorectal, endometrial, and ovarian cancers.

DATA SOURCES

Published literature.

TARGET POPULATION

All persons with newly diagnosed colorectal cancer and their relatives.

TIME HORIZON

Lifetime.

PERSPECTIVE

Third-party payer.

INTERVENTION

Strategies based on clinical criteria, prediction algorithms, tumor testing, or up-front germline mutation testing, followed by tailored screening and risk-reducing surgery.

OUTCOME MEASURES

Life-years, cancer cases and deaths, costs, and incremental cost-effectiveness ratios.

RESULTS OF BASE-CASE ANALYSIS

The benefit of all strategies accrued primarily to relatives with a mutation associated with the Lynch syndrome, particularly women, whose life expectancy could increase by approximately 4 years with hysterectomy and salpingo-oophorectomy and adherence to colorectal cancer screening recommendations. At current rates of germline testing, screening, and prophylactic surgery, the strategies reduced deaths from colorectal cancer by 7% to 42% and deaths from endometrial and ovarian cancer by 1% to 6%. Among tumor-testing strategies, immunohistochemistry followed by BRAF mutation testing was preferred, with an incremental cost-effectiveness ratio of $36,200 per life-year gained.

RESULTS OF SENSITIVITY ANALYSIS

The number of relatives tested per proband was a critical determinant of both effectiveness and cost-effectiveness, with testing of 3 to 4 relatives required for most strategies to meet a threshold of $50,000 per life-year gained. Immunohistochemistry followed by BRAF mutation testing was preferred in 59% of iterations in probabilistic sensitivity analysis at a threshold of $100,000 per life-year gained. Screening for the Lynch syndrome with immunohistochemistry followed by BRAF mutation testing only up to age 70 years cost $44,000 per incremental life-year gained compared with screening only up to age 60 years, and screening without an upper age limit cost $88,700 per incremental life-year gained compared with screening only up to age 70 years.

LIMITATION

Other types of cancer, uncertain family pedigrees, and genetic variants of unknown significance were not considered.

CONCLUSION

Widespread colorectal tumor testing to identify families with the Lynch syndrome could yield substantial benefits at acceptable costs, particularly for women with a mutation associated with the Lynch syndrome who begin regular screening and have risk-reducing surgery. The cost-effectiveness of such testing depends on the participation rate among relatives at risk for the Lynch syndrome.

PRIMARY FUNDING SOURCE

National Institutes of Health.

Genetics, genomics, and cancer risk assessment: State of the Art and Future Directions in the Era of Personalized Medicine

Scientific and technologic advances are revolutionizing our approach to genetic cancer risk assessment, cancer screening and prevention, and targeted therapy, fulfilling the promise of personalized medicine. In this monograph, we review the evolution of scientific discovery in cancer genetics and genomics, and describe current approaches, benefits, and barriers to the translation of this information to the practice of preventive medicine. Summaries of known hereditary cancer syndromes and highly penetrant genes are provided and contrasted with recently discovered genomic variants associated with modest increases in cancer risk. We describe the scope of knowledge, tools, and expertise required for the translation of complex genetic and genomic test information into clinical practice. The challenges of genomic counseling include the need for genetics and genomics professional education and multidisciplinary team training, the need for evidence-based information regarding the clinical utility of testing for genomic variants, the potential dangers posed by premature marketing of first-generation genomic profiles, and the need for new clinical models to improve access to and responsible communication of complex disease risk information. We conclude that given the experiences and lessons learned in the genetics era, the multidisciplinary model of genetic cancer risk assessment and management will serve as a solid foundation to support the integration of personalized genomic information into the practice of cancer medicine.

Strategies to identify the Lynch syndrome among patients with colorectal cancer: a cost-effectiveness analysis

BACKGROUND

Testing has been advocated for all persons with newly diagnosed colorectal cancer to identify families with the Lynch syndrome, an autosomal dominant cancer-predisposition syndrome that is a paradigm for personalized medicine.

OBJECTIVE

To estimate the effectiveness and cost-effectiveness of strategies to identify the Lynch syndrome, with attention to sex, age at screening, and differential effects for probands and relatives.

DESIGN

Markov model that incorporated risk for colorectal, endometrial, and ovarian cancers.

DATA SOURCES

Published literature.

TARGET POPULATION

All persons with newly diagnosed colorectal cancer and their relatives.

TIME HORIZON

Lifetime.

PERSPECTIVE

Third-party payer.

INTERVENTION

Strategies based on clinical criteria, prediction algorithms, tumor testing, or up-front germline mutation testing, followed by tailored screening and risk-reducing surgery.

OUTCOME MEASURES

Life-years, cancer cases and deaths, costs, and incremental cost-effectiveness ratios.

RESULTS OF BASE-CASE ANALYSIS

The benefit of all strategies accrued primarily to relatives with a mutation associated with the Lynch syndrome, particularly women, whose life expectancy could increase by approximately 4 years with hysterectomy and salpingo-oophorectomy and adherence to colorectal cancer screening recommendations. At current rates of germline testing, screening, and prophylactic surgery, the strategies reduced deaths from colorectal cancer by 7% to 42% and deaths from endometrial and ovarian cancer by 1% to 6%. Among tumor-testing strategies, immunohistochemistry followed by BRAF mutation testing was preferred, with an incremental cost-effectiveness ratio of $36,200 per life-year gained.

RESULTS OF SENSITIVITY ANALYSIS

The number of relatives tested per proband was a critical determinant of both effectiveness and cost-effectiveness, with testing of 3 to 4 relatives required for most strategies to meet a threshold of $50,000 per life-year gained. Immunohistochemistry followed by BRAF mutation testing was preferred in 59% of iterations in probabilistic sensitivity analysis at a threshold of $100,000 per life-year gained. Screening for the Lynch syndrome with immunohistochemistry followed by BRAF mutation testing only up to age 70 years cost $44,000 per incremental life-year gained compared with screening only up to age 60 years, and screening without an upper age limit cost $88,700 per incremental life-year gained compared with screening only up to age 70 years.

LIMITATION

Other types of cancer, uncertain family pedigrees, and genetic variants of unknown significance were not considered.

CONCLUSION

Widespread colorectal tumor testing to identify families with the Lynch syndrome could yield substantial benefits at acceptable costs, particularly for women with a mutation associated with the Lynch syndrome who begin regular screening and have risk-reducing surgery. The cost-effectiveness of such testing depends on the participation rate among relatives at risk for the Lynch syndrome.

PRIMARY FUNDING SOURCE

National Institutes of Health.

High risk of colorectal and endometrial cancer in Ashkenazi families with the MSH2 A636P founder mutation

BACKGROUND & AIMS

The MSH2 A636P mutation is a founder mutation in Ashkenazi Jews that causes Lynch syndrome, with a prevalence of 0.4%-0.7%. Estimates of age-specific cumulative risk and lifetime risk for colorectal cancer (CRC) and endometrial cancer (EC) specific to carriers of this mutation are not available.

METHODS

We studied 27 families with MSH2 A636P gene mutations identified in Israel; 13 were identified via a population-based, case-control study and 14 were identified from a clinical genetics service. Age-specific cumulative risks (penetrance) and hazard ratio (HR) estimates of CRC and EC risks were calculated and compared with the general Ashkenazi population using modified segregation analysis. An ascertainment-corrected likelihood that combined population-based and clinic-based sampling provided a powerful analysis for estimating penetrance. We analyzed 74 cases of CRC (40 in the clinic series and 34 in the population-based series), diagnosed at median ages of 50 years (men) and 49 years (women) in the combined sample.

RESULTS

The cumulative risk of CRC at age 70 was 61.62% for men (95% confidence interval [CI], 37.49%-76.45%) and 61.08% for women (95% CI, 39.39%-75.14%), with overall HRs of 31.8 (19.9-51.0) and 41.8 (27.4-64.0), respectively. There were 28 cases of EC, diagnosed at a median age of 53.0 years. The cumulative risk of EC was 55.64% (95% CI, 33.07%-70.58%) with an overall HR of 66.7 (41.7-106.7).

CONCLUSIONS

Lifetime risks of CRC and EC in MSH2 A636P carriers are high even after adjusting for ascertainment. These estimates are valuable for patients and providers; specialized cancer screening is necessary for carriers of this mutation.

Health benefits and cost-effectiveness of primary genetic screening for Lynch syndrome in the general population

In current clinical practice, genetic testing to detect Lynch syndrome mutations ideally begins with diagnostic testing of an individual affected with cancer before offering predictive testing to at-risk relatives. An alternative strategy that warrants exploration involves screening unaffected individuals via demographic and family histories, and offering genetic testing to those individuals whose risks for carrying a mutation exceed a selected threshold. Whether this approach would improve health outcomes in a manner that is cost-effective relative to current standards of care has yet to be demonstrated. To do so, we developed a simulation framework that integrated models of colorectal and endometrial cancers with a 5-generation family history model to predict health and economic outcomes of 20 primary screening strategies (at a wide range of compliance levels) aimed at detecting individuals with mismatch repair gene mutations and their at-risk relatives. These strategies were characterized by (i) different screening ages for starting risk assessment and (ii) different risk thresholds above which to implement genetic testing. For each strategy, 100,000 simulated individuals, representative of the U.S. population, were followed from the age of 20, and the outcomes were compared with current practice. Findings indicated that risk assessment starting at ages 25, 30, or 35, followed by genetic testing of those with mutation risks exceeding 5%, reduced colorectal and endometrial cancer incidence in mutation carriers by approximately 12.4% and 8.8%, respectively. For a population of 100,000 individuals containing 392 mutation carriers, this strategy increased quality-adjusted life-years (QALY) by approximately 135 with an average cost-effectiveness ratio of $26,000 per QALY. The cost-effectiveness of screening for mismatch repair gene mutations is comparable to that of accepted cancer screening activities in the general population such as colorectal cancer screening, cervical cancer screening, and breast cancer screening. These results suggest that primary screening of individuals for mismatch repair gene mutations, starting with risk assessment between the ages of 25 and 35, followed by genetic testing of those whose risk exceeds 5%, is a strategy that could improve health outcomes in a cost-effective manner relative to current practice.