The role of mismatch repair gene defects in the development of adenomas in patients with HNPCC

Lynch Syndrome-Impact of the Type of Deficient Mismatch Repair Gene Mutation on Diagnosis, Clinical Presentation, Surveillance and Therapeutic Approaches

In today's world, with its continuing advancements in genetics, the identification of Lynch syndrome (LS) increasingly relies on sophisticated genetic testing techniques. Most guidelines recommend a tailored surveillance program, as well as personalized prophylactic and therapeutic approaches, according to the type of dMMR gene mutation. Carriers of path_MLH1 and path_MSH2 genes have a higher risk of developing colorectal cancer (CRC), despite intensive colonoscopic surveillance. Conversely, carriers of path_MSH6 and path_PMS2 genes have a lower risk of developing CRC, which may be due to their lower penetrance and later age of onset. Thus, carriers of path_MLH1 or path_MSH2 would theoretically derive greater benefits from total colectomy, compared to low-risk carriers (path_MSH6 and path_PMS2), in which colonoscopic surveillance might achieve an efficient prophylaxis. Furthermore, regarding the risk of endometrial/ovarian cancer development, there is a global agreement to offer both hysterectomy and bilateral salpingo-oophorectomy to path_MLH1, path_MSH2 and path_MSH6 carriers after the age of 40. In patients with CRC, preoperative knowledge of the diagnosis of LS is of tremendous importance, due to the high risk of metachronous CRC. However, this risk depends on the type of dMMR gene mutation. For carriers of the high-risk variants (MLH1, MSH2 and EPCAM) who have already developed colon cancer, it is strongly recommended a subtotal or total colectomy is performed, while partial colectomy followed by endoscopic surveillance is an appropriate management approach to treat colon cancer in carriers of the low-risk variants (MSH6 and PMS2). On the other hand, extended surgery for index rectal cancer (such as total proctocolectomy) is less effective than extended surgery for index colon cancer from the point of view of metachronous CRC risk reduction, and is associated with a decreased quality of life.

An artificial intelligence-assisted system versus white light endoscopy alone for adenoma detection in individuals with Lynch syndrome (TIMELY): an international, multicentre, randomised controlled trial

BACKGROUND

Computer-aided detection (CADe) systems for colonoscopy have been shown to increase small polyp detection during colonoscopy in the general population. People with Lynch syndrome represent an ideal target population for CADe-assisted colonoscopy because adenomas, the primary cancer precursor lesions, are characterised by their small size and higher likelihood of showing advanced histology. We aimed to evaluate the performance of CADe-assisted colonoscopy in detecting adenomas in individuals with Lynch syndrome.

METHODS

TIMELY was an international, multicentre, parallel, randomised controlled trial done in 11 academic centres and six community centres in Belgium, Germany, Italy, and Spain. We enrolled individuals aged 18 years or older with pathogenic or likely pathogenic MLH1, MSH2, MSH6, or EPCAM variants. Participants were consecutively randomly assigned (1:1) to either CADe (GI Genius) assisted white light endoscopy (WLE) or WLE alone. A centre-stratified randomisation sequence was generated through a computer-generated system with a separate randomisation list for each centre according to block-permuted randomisation (block size 26 patients per centre). Allocation was automatically provided by the online AEG-REDCap database. Participants were masked to the random assignment but endoscopists were not. The primary outcome was the mean number of adenomas per colonoscopy, calculated by dividing the total number of adenomas detected by the total number of colonoscopies and assessed in the intention-to-treat population. This trial is registered with ClinicalTrials.gov, NCT04909671.

FINDINGS

Between Sept 13, 2021, and April 6, 2023, 456 participants were screened for eligibility, 430 of whom were randomly assigned to receive CADe-assisted colonoscopy (n=214) or WLE (n=216). 256 (60%) participants were female and 174 (40%) were male. In the intention-to-treat analysis, the mean number of adenomas per colonoscopy was 0·64 (SD 1·57) in the CADe group and 0·64 (1·17) in the WLE group (adjusted rate ratio 1·03 [95% CI 0·72-1·47); p=0·87). No adverse events were reported during the trial.

INTERPRETATION

In this multicentre international trial, CADe did not improve the detection of adenomas in individuals with Lynch syndrome. High-quality procedures and thorough inspection and exposure of the colonic mucosa remain the cornerstone in surveillance of Lynch syndrome.

FUNDING

Spanish Gastroenterology Association, Spanish Society of Digestive Endoscopy, European Society of Gastrointestinal Endoscopy, Societat Catalana de Digestologia, Instituto Carlos III, Beca de la Marato de TV3 2020. Co-funded by the European Union.

Nfe2l2/NRF2 Deletion Attenuates Tumorigenesis and Increases Bacterial Diversity in a Mouse Model of Lynch Syndrome

Lynch syndrome (LS) is the most prevalent heritable form of colorectal cancer. Its early onset and high lifetime risk for colorectal cancer emphasize the necessity for effective chemoprevention. NFE2L2 (NRF2) is often considered a potential druggable target, and many chemopreventive compounds induce NRF2. However, although NRF2 counteracts oxidative stress, it is also overexpressed in colorectal cancer and may promote tumorigenesis. In this study, we evaluated the role of NRF2 in the prevention of LS-associated neoplasia. We found increased levels of NRF2 in intestinal epithelia of mice with intestinal epithelium-specific Msh2 deletion (MSH2ΔIEC) compared with C57BL/6 (wild-type) mice, as well as an increase in downstream NRF2 targets NAD(P)H dehydrogenase (quinone 1) and glutamate-cysteine ligase catalytic subunit. Likewise, NRF2 levels were increased in human MSH2-deficient LS tumors compared with healthy human controls. In silico analysis of a publicly accessible RNA sequencing LS dataset also found an increase in downstream NRF2 targets. Upon crossing MSH2ΔIEC with Nrf2null (MSH2ΔIECNrf2null) mice, we unexpectedly found reduced tumorigenesis in MSH2ΔIECNrf2null mice compared with MSH2ΔIEC mice after 40 weeks, which occurred despite an increase in oxidative damage in MSH2ΔIECNrf2null mice. The loss of NRF2 impaired proliferation as seen by Ki67 intestinal staining and in organoid cultures. This was accompanied by diminished WNT/β-catenin signaling, but apoptosis was unaffected. Microbial α-diversity increased over time with the loss of NRF2 based upon 16S rRNA gene amplicon sequencing of murine fecal samples. Altogether, we show that NRF2 protein levels are increased in MSH2 deficiency and associated neoplasia, but the loss of NRF2 attenuates tumorigenesis. Activation of NRF2 may not be a feasible strategy for chemoprevention in LS. Prevention Relevance: Patients with LS have an early onset and high lifetime risk for colorectal cancer. In this study, we show that NRF2 protein levels are increased in MSH2 deficiency and associated neoplasia, but the loss of NRF2 attenuates tumorigenesis. This suggests that NRF2 may not be a tumor suppressor in this specific context.

The diagnostic yield of colonoscopic surveillance following resection of early age onset colorectal cancer

BACKGROUND

The primary benefit of post-colorectal cancer (CRC) colonoscopic surveillance is to detect and remove premalignant lesions to prevent metachronous CRC. Current guidelines for long-term colonoscopic surveillance post early age onset CRC (EOCRC) resection are based on limited evidence. The aims of this study were to assess the diagnostic yield of colonoscopic surveillance post-EOCRC resection and identify molecular and clinicopathological risk factors associated with advanced neoplasia.

METHODOLOGY

A retrospective cohort study of prospectively collected data was conducted at St Mark's hospital, London, United Kingdom, for patients diagnosed with EOCRC who underwent at least one episode of post-CRC colonoscopic surveillance between 1978 and 2022. We collected clinicopathological data including tumour molecular status and neoplasia detection rates.

RESULTS

In total, 908 colonoscopic surveillance procedures were performed in 195 patients over 2581.3 person-years of follow-up. The diagnostic yields of metachronous CRC, advanced adenomas and non-advanced adenomas were 1.76%, 3.41% and 22.69% respectively. Sixteen patients (8.21%) developed metachronous CRC, and the majority (87.5%) were detected more than 3 years post index EOCRC diagnosis. Detection of advanced neoplasia was significantly higher in EOCRC patients with Lynch syndrome (26.15%) compared with those in whom Lynch syndrome was excluded (13.13%) (OR, 2.343; 95% CI, 1.014-5.256; p = 0.0349).

CONCLUSIONS

During colonoscopic surveillance post-EOCRC resection, the long-term risk of developing metachronous advanced neoplasia remains high in the context of Lynch syndrome, but this trend is not as clearly evident when Lynch syndrome has been excluded.

Features of colorectal adenomas among young patients with Lynch syndrome according to path_MMR: Results from the PRED-IdF registry

BACKGROUND

Lynch syndrome (LS) is the most frequent inherited colorectal cancer syndrome.

AIM

To assess the burden of adenoma in LS patients under 50 years-old followed in the PRED-IdF network.

METHODS

From January 2010 to January 2019, all patients under 50 years of age with a confirmed LS germline mutation were included. The main objective was the description of adenomas characteristics according to path_MMR.

RESULTS

We analyzed data from 708 patients (mean age 34.8 ± 8.6), of which 41.8 % were male. Among these patients, 37.6% had path_MLH1, 45.4% path_MSH2, 13.9% path_MSH6, 2.9% path_PMS2, and 1.2% path_EpCAM. The analysis included 1721 (70.9%) follow-up colonoscopies. A total of 682 adenomas were detected, including 140 (20.5%) advanced adenomas. The adenoma detection rates during the first and follow-up colonoscopies were 19.2% and 20.5%, respectively. Most adenomas were <10 mm (57.9%), located in the proximal colon (334, 48.9%), and presented as non-polypoid lesions (493, 72.3%). The median growth time for adenomas was 23 months (range 9-114) irrespective of the path_MMR mutation (p = 0.62).

CONCLUSION

LS patients under 50 years of age have a high burden of adenomas, particularly small non-polypoid adenomas located in the proximal colon. These results highlight the need for intensive screening, with a particular focus on the proximal colon.

Germline Variants in MLH1 and ATM Genes in a Young Patient with MSI-H in a Precancerous Colonic Lesion

Lynch syndrome (LS) is an autosomal dominant inherited disorder that primarily predisposes individuals to colorectal and endometrial cancer. It is associated with pathogenic variants in DNA mismatch repair (MMR) genes. In this study, we report the case of a 16-year-old boy who developed a precancerous colonic lesion and had a clinical suspicion of LS. The proband was found to have a somatic MSI-H status. Analysis of the coding sequences and flanking introns of the MLH1 and MSH2 genes by Sanger sequencing led to the identification of the variant of uncertain significance, namely, c.589-9_589-6delGTTT in the MLH1 gene. Further investigation revealed that this variant was likely pathogenetic. Subsequent next-generation sequencing panel analysis revealed the presence of two variants of uncertain significance in the ATM gene. We conclude that the phenotype of our index case is likely the result of a synergistic effect of these identified variants. Future studies will allow us to understand how risk alleles in different colorectal-cancer-prone genes interact with each other to increase an individual's risk of developing cancer.

Outcomes of upper endoscopy screening in Lynch syndrome: a meta-analysis

BACKGROUND AND AIMS

Lynch syndrome (LS) predisposes affected individuals to a high lifetime risk of malignancies, including colorectal, endometrial, gastric, and duodenal cancers. The role of upper GI (UGI) cancer screening in LS has been uncertain, but recent studies have evaluated its utility.

METHODS

Databases were queried through December 2021 to identify studies that examined upper endoscopy screening in LS using EGD. Mantel-Haenszel pooled odds ratios and 95% confidence intervals (CIs) for outcomes were constructed using a random-effects model to identify pooled odds of endoscopic findings in persons with LS. Event rates for detection of gastric and duodenal cancers, high-risk lesions, and clinically actionable findings were calculated. Statistical heterogeneity was assessed using the I² statistic.

RESULTS

Nine studies were identified with 2356 LS patients undergoing approximately 7838 EGDs. In total, 47 LS-associated UGI cancers (18 gastric and 29 duodenal cancers), 237 high-risk lesions, and 335 clinically actionable findings were identified. The pooled event rate for detection of any UGI cancer, high-risk lesions, and clinically actionable findings during screening were .9% (95% CI, .3-2.1; I² = 89%), 4.2% (95% CI, 1.6-10.9; I² = 98%), and 6.2% (95% CI, 2.2-16.5; I² = 99%), respectively. There was no difference between LS-associated gene and gastric or duodenal cancer detection.

CONCLUSIONS

In LS, there is evidence that endoscopic screening detects UGI cancers, precancerous lesions, and other clinically actionable findings that favor its use as a part of cancer risk management in LS.

Upper Gastrointestinal Cancer Surveillance in Lynch Syndrome

Simple Summary

Lynch syndrome is the most common cause of hereditary colorectal cancer, but is also associated with increased extracolonic cancer risk, including upper gastrointestinal cancers. While there is agreement regarding the benefit of frequent colonoscopic surveillance in Lynch syndrome, there remains a lack of consensus on the use of upper gastrointestinal cancer surveillance. Here, we review the upper gastrointestinal cancer risks in Lynch syndrome, the varying guideline recommendations in this area, and the published outcomes of upper gastrointestinal cancer surveillance in this high-risk population. Finally, we highlight ongoing controversies in upper gastrointestinal cancer surveillance and opine on how upper gastrointestinal cancer surveillance can be incorporated into a Lynch syndrome risk management program. Upper gastrointestinal cancer surveillance is an increasingly studied area of risk management in Lynch syndrome, and continued research will be vital in determining how to best incorporate this surveillance in these high-risk patients.

Abstract

Lynch syndrome is a common hereditary cancer predisposition syndrome associated with increased digestive cancer risk including colorectal, gastric, and duodenal cancers. While colorectal cancer surveillance is widely accepted to be an important part of a comprehensive Lynch syndrome risk management plan, the use of upper gastrointestinal cancer surveillance in Lynch syndrome remains more controversial. Currently, upper gastrointestinal cancer surveillance guidelines for Lynch syndrome vary widely, and there is no consensus on who should undergo upper gastrointestinal cancer surveillance, how surveillance should be performed, the age at which to initiate surveillance, or how often individuals with Lynch syndrome should undergo upper gastrointestinal cancer surveillance. Fortunately, research groups around the world have been focusing on upper gastrointestinal cancer surveillance in Lynch syndrome, and recent evidence in this field has demonstrated that upper gastrointestinal cancer surveillance can be performed with identification of precancerous lesions as well as early-stage upper gastrointestinal cancers. In this manuscript, we review the upper gastrointestinal cancer risks in Lynch syndrome, differing guideline recommendations for surveillance, outcomes of upper gastrointestinal cancer surveillance, and controversies in the field, and we provide a framework based on our collective experience with which to incorporate upper gastrointestinal cancer surveillance into a risk management program for individuals with Lynch syndrome.

Genetic testing for assessment of lynch syndrome in young patients with polyps

BACKGROUND

Routine screening for establishing Lynch syndrome (LS) in young individuals diagnosed with adenomas is not recommended due to its low yield, and limited sensitivity of the employment of immunohistochemistry for DNA mismatch-repair proteins on polyps. Hence we aimed to evaluate the yield of germline mutational analysis in diagnosis of LS in a young Israeli cohort with colorectal adenomatous polyps.

METHODS

Data were retrospectively collected on consecutive patients, age ≤ 45 years, who underwent colonoscopy with removal of at least one adenoma during 2015-2020, and subsequently genetic testing by multigene panel or LS-Jewish founder mutation panel.

RESULTS

Overall, 92 patients were included (median age 35 years, range 23-45 years), of whom 79 (85.8%) underwent multigene panel genotyping, and 13 (14.2%) analysis for Jewish founder LS gene mutations. Altogether, 18 patients were identified with pathogenic mutations in actionable genes, including LS-associated genes in 6 (6.5%), BRCA2 in 2 (2.5%), GREM1 in 1(1.2%), and low-penetrance genes- APC I1307K and CHEK2- in 9 (11.4%) patients. Compared with non-LS patients, LS-carriers had a significantly higher median PREMM5 score (2.6 vs. 1.3; P = 0.04).

CONCLUSIONS

Young individuals diagnosed with adenomatous polyps should be offered genetic testing when fulfilling clinical guidelines for LS, but weight should also be given to adenoma characteristics in the PREMM5 score.

Endoscopy to Diagnose and Prevent Digestive Cancers in Lynch Syndrome

Lynch syndrome patients could benefit from various recommendations to prevent digestive cancers. In this review, we summarize the criteria to identify Lynch syndrome in patients with digestive cancers. We detail endoscopic screening procedures in patients with Lynch syndrome for gastric, small bowel, pancreatic, and colorectal cancers. We review the precise modalities of endoscopic follow-up, particularly the discrepancies that exist between the guidelines of the various scientific societies. We discuss the treatment of colorectal cancers in Lynch syndrome cases and patient adherence to endoscopic follow-up programs.

From Genetics to Histomolecular Characterization: An Insight into Colorectal Carcinogenesis in Lynch Syndrome

Lynch syndrome is a hereditary cancer-predisposing syndrome caused by germline defects in DNA mismatch repair (MMR) genes such as MLH1, MSH2, MSH6, and PMS2. Carriers of pathogenic mutations in these genes have an increased lifetime risk of developing colorectal cancer (CRC) and other malignancies. Despite intensive surveillance, Lynch patients typically develop CRC after 10 years of follow-up, regardless of the screening interval. Recently, three different molecular models of colorectal carcinogenesis were identified in Lynch patients based on when MMR deficiency is acquired. In the first pathway, adenoma formation occurs in an MMR-proficient background, and carcinogenesis is characterized by APC and/or KRAS mutation and IGF2, NEUROG1, CDK2A, and/or CRABP1 hypermethylation. In the second pathway, deficiency in the MMR pathway is an early event arising in macroscopically normal gut surface before adenoma formation. In the third pathway, which is associated with mutations in CTNNB1 and/or TP53, the adenoma step is skipped, with fast and invasive tumor growth occurring in an MMR-deficient context. Here, we describe the association between molecular and histological features in these three routes of colorectal carcinogenesis in Lynch patients. The findings summarized in this review may guide the use of individualized surveillance guidelines based on a patient’s carcinogenesis subtype.

Prevalence of Mismatch Repair-Deficient Colorectal Adenoma/Polyp in Early-Onset, Advanced Cases: a Cross-Sectional Study Based on Iranian Hereditary Colorectal Cancer Registry

BACKGROUND

Lynch syndrome (LS) increases the risk of many types of cancer, mainly colorectal cancer (CRC). The purpose of this study was to assess the prevalence of mismatch repair (MMR) deficiency in patients under the age of 50 with advanced adenomatous polyps, aiming at an early diagnosis of LS.

METHODS

This retrospective, cross-sectional study included eligible patients with advanced adenomas diagnosed ≤ 50 years of age registered between April 2014 and February 2017 at three pathology centers in Mashhad. Pathological records were reviewed, and colon tissue specimens were analyzed by immunohistochemistry (IHC) staining to identify proteins which serve as markers for LS as they are related to loss of MMR gene (MLH1, MSH2, MSH6, and PMS2) expression.

RESULTS

Of 862 consecutive patients, a total of 50 adenomas (54% males, 46% females of mean age 41.24 ± 6.5) met the eligibility criteria. Of the adenomas examined, 20 (40%) had a tubulovillous component, 34 (68%) had high-grade dysplasia, and 30 (60%) had were larger than 10 mm protrusions. None of the patients had loss of MMR protein expression.

CONCLUSION

No individual with MMR genetic disorder was identified by IHC screening of early-onset advanced colorectal adenomas. This strategy is therefore not an effective strategy for detecting MMR mutation carriers.

A Meta-Analysis of Obesity and Risk of Colorectal Cancer in Patients with Lynch Syndrome: The Impact of Sex and Genetics

There appears to be a sex-specific association between obesity and colorectal neoplasia in patients with Lynch Syndrome (LS). We meta-analyzed studies reporting on obesity and colorectal cancer (CRC) risk in LS patients to test whether obese subjects were at increased risk of cancer compared to those of normal weight. We explored also a possible sex-specific relationship between adiposity and CRC risk among patients with LS. The summary relative risk (SRR) and 95% confidence intervals (CI) were calculated through random effect models. We investigated the causes of between-study heterogeneity and assessed the presence of publication bias. We were able to retrieve suitable data from four independent studies. We found a twofold risk of CRC in obese men compared to nonobese men (SRR = 2.09; 95%CI: 1.23–3.55, I² = 33%), and no indication of publication bias (p = 0.13). No significantly increased risk due to obesity was found for women. A 49% increased CRC risk for obesity was found for subjects with an MLH1 mutation (SRR = 1.49; 95%CI: 1.11–1.99, I² = 0%). These results confirm the different effects of sex on obesity and CRC risk and also support the public measures to reduce overweight in people with LS, particularly for men.

Malignant potential of colorectal neoplasms in Lynch syndrome: an analysis of 325 lesions endoscopically treated at a single institute

BACKGROUND

Patients with Lynch syndrome are at an increased risk of developing colorectal cancer, and the adenoma-carcinoma sequence is accelerated in these patients. However, the clinicopathological characteristics of colorectal neoplasms in Lynch syndrome patients are not well-known.

METHODS

A total of 325 consecutive colorectal neoplasms were endoscopically removed from 68 patients with Lynch syndrome between June 2005 and May 2018 and retrospectively reviewed.

RESULTS

Of the 325 lesions, 94 (29%), 220 (68%) and 11 (3%) were from patients with MLH1, MSH2 and MSH6 mutations, respectively. The median lesion size was 5 mm (range 2-40 mm), with 229 (71%) lesions having a non-polypoid morphology. The frequencies of advanced neoplasms, including high-grade adenomas, intramucosal carcinomas and submucosal invasive carcinomas were 14, 34, 97 and 93% for lesions with diameters of <5, ≥5 and <10, ≥10 and <20, and ≥20 mm, respectively. The frequencies of advanced neoplasms in the proximal colon, distal colon and rectum did not significantly differ (36, 35 and 41%, respectively).

CONCLUSIONS

Our results suggest that the malignant transformation interval from low-grade adenomas to advanced neoplasms is similar in all parts of the colon. Furthermore, since one-third of neoplastic lesions with diameters of ≥5 and <10 mm and most of those ≥10 mm were advanced neoplasms, we recommend that in Lynch syndrome patients, careful colonoscopic surveillance should be performed throughout the colon, and all neoplastic lesions, regardless of the size, should be subjected to detailed endoscopic examination, complete resection and detailed pathological examination.

Colorectal cancer screening in Lynch syndrome: Indication, techniques and future perspectives

Lynch syndrome (LS) is an inherited predisposition to colorectal cancer (CRC), responsible for 3-5% of all CRC. This syndrome is characterized by the early occurrence of colorectal neoplastic lesions, with variable incidences depending on the type of pathogenic variants in MMR genes (MLH1, MSH2, MSH6, PMS2 and EPCAM) and demographics factors such as gender, body mass index, tobacco use and physical activity. Similar to sporadic cancers, colorectal screening by colonoscopy is efficient because it is associated with a reduction >50% of both CRC incidence and CRC related mortality. To that end, most guidelines recommend high definition screening colonoscopies in dedicated centers, starting at the age of 20-25 years old, with a surveillance interval of 1-2 years. In this review, we discuss the importance of high definition colonoscopies, including the compliance to specific key performance indicators, as well as the expected benefits of specific imaging modalities including virtual chromoendoscopy and dye-spray chromoendoscopy.

Discovering the Mutational Profile of Early Colorectal Lesions: A Translational Impact

Simple Summary

Colorectal cancer (CRC) is one of the most common malignancies worldwide. Next-generation sequencing technologies have identified new candidate genes and deepened the knowledge of the molecular mechanisms underlying the progression of colonic adenomas towards CRC. The main genetic, epigenetic, and molecular alterations driving the onset and progression of CRC in both hereditary and sporadic settings have also been investigated. The evaluation of the CRC risk based on the molecular characterization of early pre-cancerous lesions may contribute to the development of targeted preventive strategies development, help define specific risk profiles, and identify patients who will benefit from targeted endoscopic surveillance.

Abstract

Colorectal cancer (CRC) develops through a multi-step process characterized by the acquisition of multiple somatic mutations in oncogenes and tumor-suppressor genes, epigenetic alterations and genomic instability. These events lead to the progression from precancerous lesions to advanced carcinomas. This process requires several years in a sporadic setting, while occurring at an early age and or faster in patients affected by hereditary CRC-predisposing syndromes. Since advanced CRC is largely untreatable or unresponsive to standard or targeted therapies, the endoscopic treatment of colonic lesions remains the most efficient CRC-preventive strategy. In this review, we discuss recent studies that have assessed the genetic alterations in early colorectal lesions in both hereditary and sporadic settings. Establishing the genetic profile of early colorectal lesions is a critical goal in the development of risk-based preventive strategies.

Upper Gastrointestinal Lesions during Endoscopy Surveillance in Patients with Lynch Syndrome: A Multicentre Cohort Study

BACKGROUND

Patients with Lynch syndrome are at increased risk of gastric and duodenal cancer. Upper gastrointestinal endoscopy surveillance is generally proposed, even though little data are available on upper gastrointestinal endoscopy in these patients. The aim of this retrospective study was to evaluate the prevalence and incidence of gastrointestinal lesions following upper gastrointestinal endoscopy examination in Lynch patients.

METHODS

A large, multicentre cohort of 172 patients with a proven germline mutation in one of the mismatch repair genes and at least one documented upper gastrointestinal endoscopy screening was assessed. Detailed information was collected on upper gastrointestinal endoscopy findings and the outcome of endoscopic follow-up.

RESULTS

Seventy neoplastic gastrointestinal lesions were diagnosed in 45 patients (26%) out of the 172 patients included. The median age at diagnosis of upper gastrointestinal lesions was 54 years. The prevalence of cancer at initial upper gastrointestinal endoscopy was 5% and the prevalence of precancerous lesions was 12%. Upper gastrointestinal lesions were more frequent after 40 years of age (p < 0.001). Helicobacter pylori infection was associated with an increased prevalence of gastric, but not duodenal, lesions (p < 0.001).

CONCLUSIONS

Neoplastic upper gastrointestinal lesions are frequent in patients with Lynch syndrome, especially in those over 40 years of age. The results of our study suggest that Lynch patients should be considered for upper gastrointestinal endoscopic and Helicobacter pylori screening.

The "unnatural" history of colorectal cancer in Lynch syndrome: Lessons from colonoscopy surveillance

Individuals with Lynch syndrome (LS), one of the most common inherited cancer syndromes, are at increased risk of developing malignancies, in particular colorectal cancer (CRC). Regular colonoscopy with polypectomy is recommended to reduce CRC risk in LS individuals. However, recent independent studies demonstrated that a substantial proportion of LS individuals develop CRC despite regular colonoscopy. The reasons for this surprising observation confirmed by large prospective studies are a matter of debate. In this review, we collect existing evidence from clinical, epidemiological and molecular studies and interpret them with regard to the origins and progression of LS-associated CRC. Alongside with hypotheses addressing colonoscopy quality and pace of progression from adenoma to cancer, we discuss the role of alternative precursors and immune system in LS-associated CRC. We also identify gaps in current knowledge and make suggestions for future studies aiming at improved CRC prevention for LS individuals.

Associations of Height With the Risks of Colorectal and Endometrial Cancer in Persons With Lynch Syndrome

People with Lynch syndrome (LS), who carry a pathogenic mutation in a DNA mismatch repair gene, have increased risks of colorectal cancer (CRC) and endometrial cancer (EC). A high reported variability in cancer risk suggests the existence of factors that modify cancer risk for persons with LS. We aimed to investigate the associations between height and CRC and EC risk for persons with LS using data from 2 large studies. Information on 1,115 men and 1,553 women with LS from the Colon Cancer Family Registry (1998–2007) and the GEOLynch Cohort Study (2006–2017) was harmonized. We used weighted Cox proportional hazards regression models with age on the time axis to estimate adjusted hazard ratios and 95% confidence intervals for each 5-cm increment in self-reported height. CRC was diagnosed in 947 persons during 65,369 person-years of observation, and 171 women were diagnosed with EC during 39,227 person-years. Height was not associated with CRC for either men (per 5-cm increment, hazard ratio (HR) = 1.00, 95% confidence interval (CI): 0.91, 1.11) or women (per 5-cm increment, HR = 1.01, 95% CI: 0.92, 1.11), nor was height associated with EC (per 5-cm increment, HR = 1.08, 95% CI: 0.94, 1.24). Hence, we observed no evidence for an association of height with either CRC or EC among persons with LS.

Diagnosis of Lynch Syndrome and Strategies to Distinguish Lynch-Related Tumors from Sporadic MSI/dMMR Tumors

Simple Summary

Microsatellite instability (MSI) is a hallmark of Lynch syndrome (LS)-related tumors but is not specific, as most of MSI/mismatch repair-deficient (dMMR) tumors are sporadic. Therefore, the identification of MSI/dMMR requires additional diagnostic tools to identify LS. In this review, we address the hallmarks of LS and present recent advances in diagnostic and screening strategies to identify LS patients. We also discuss the pitfalls associated with current strategies, which should be taken into account in order to improve the diagnosis of LS.

Abstract

Microsatellite instability (MSI) is a hallmark of Lynch syndrome (LS)-related tumors but is not specific to it, as approximately 80% of MSI/mismatch repair-deficient (dMMR) tumors are sporadic. Methods leading to the diagnosis of LS have considerably evolved in recent years and so have tumoral tests for LS screening and for the discrimination of LS-related to MSI-sporadic tumors. In this review, we address the hallmarks of LS, including the clinical, histopathological, and molecular features. We present recent advances in diagnostic and screening strategies to identify LS patients. We also discuss the pitfalls associated with the current strategies, which should be taken into account to improve the diagnosis of LS and avoid inappropriate clinical management.

Progress Report: New insights into the prevention of CRC by colonoscopic surveillance in Lynch syndrome

Lynch syndrome is the most frequent hereditary colorectal cancer (CRC) syndrome, affecting approximately 1 in 300 in the Western population. It is caused by pathogenic variants in the mismatch repair (MMR) genes including MLH1, MSH2 (EPCAM), MSH6 and PMS2, and is associated with high risks of CRC, endometrial cancer and other cancers. In view of these risks, carriers of such variants are encouraged to participate in colonoscopic surveillance programs that are known to substantially improve their prognosis. In the last decade several important studies have been published that provide detailed cancer risk estimates and prognoses based on large numbers of patients. These studies also provided new insights regarding the pathways of carcinogenesis in CRC, which appear to differ depending on the specific MMR gene defect. In this report, we will discuss the implications of these new findings for the development of new surveillance protocols.

Prognostic Value and Immunohistochemical Analysis of Mismatch Repair Deficiency in Patients with Stage II and III Colorectal Carcinoma-A Single-Center Study

Background and objectives: Deficient mismatch repair (MMR) status is associated with good prognosis but poor therapeutic response to adjuvant chemotherapy in patients with colorectal cancer. However, there are some opposed arguments considering therapeutic outcomes in patients with evidenced MMR deficiency in colorectal cancer. The aim of the study was the investigation of prognostic value and immunohistochemical analysis of the MMR-deficiency tumors. Materials and Methods: The study enrolled 104 patients with resected stage II and III colorectal cancer samples from the period 2018–2019. Results: The tumors with deficient MMR status were significantly associated with age up to 50 years and right-sided localization (p < 0.001). During the follow-up period of 22.43 ± 6.66 months, 21 patients (20.2%) died, whereas 14 patients (13.5%) had relapses. The loss of mutL homologue 1/postmeiotic segregation increased 2 (MLH1/PMS2) expression, compared to proficient MMR tumors, was associated with shorter disease-free survival in patients with lymphovascular invasion (p < 0.05), perineural invasion (p < 0.01), stage III (p < 0.05) and high-grade tumor (p < 0.05). Conclusions: This retrospective pilot study of a single-center cohort of patients with stage II and III colorectal cancer highlights the clinical importance of using immunohistochemistry (IHC) analysis as a guide for diagnostic algorithm in a country with limited resources, but with a high prevalence of colorectal carcinoma in the young patients. MMR-deficiency tumors compared with proficient MMR colorectal cancer was not shown to be a significant predictor of disease-free and overall survival.

Complete Loss of EPCAM Immunoexpression Identifies EPCAM Deletion Carriers in MSH2-Negative Colorectal Neoplasia

Simple Summary

Colorectal carcinomas from patients with Lynch syndrome (LS) due to EPCAM deletions show loss of MSH2 expression. The aim of our study was to evaluate the usefulness of EPCAM expression in identifying carriers of EPCAM deletion among patients with MSH2-negative lesions. MSH2 and EPCAM immunohistochemistry was performed in a large series of lesions (190) composed of malignant and benign neoplasms as well as precursor lesions of different organs from 71 patients with suspected LS due to MSH2 alterations. Germ-line analysis confirmed LS in 68 patients due to MSH2 mutations (53) and EPCAM deletions (15). Among colorectal lesions with lack of MSH2 expression, only 17 were EPCAM-negative and belonged to patients with EPCAM deletions. We confirm that loss of EPCAM expression identifies EPCAM deletion carriers with 100% specificity and we recommend adding EPCAM IHC to the algorithm of MSH2-negative colorectal neoplasia.

Abstract

The use of epithelial cell adhesion molecule (EPCAM) immunohistochemistry (IHC) is not included in the colorectal cancer (CRC) screening algorithm to detect Lynch syndrome (LS) patients. The aim of the present study was to demonstrate that EPCAM IHC is a useful tool to guide the LS germ-line analysis when a loss of MSH2 expression was present. We retrospectively studied MSH2 and EPCAM IHC in a large series of 190 lesions composed of malignant neoplasms (102), precursor lesions of gastrointestinal (71) and extra-gastrointestinal origin (9), and benign neoplasms (8) from different organs of 71 patients suspicious of being LS due to MSH2 alterations. LS was confirmed in 68 patients, 53 with MSH2 mutations and 15 with EPCAM 3′-end deletions. Tissue microarrays were constructed with human normal tissues and their malignant counterparts to assist in the evaluation of EPCAM staining. Among 154 MSH2-negative lesions, 17 were EPCAM-negative, including 10 CRC and 7 colorectal polyps, and 5 of them showed only isolated negative glands. All lesions showing a lack of EPCAM expression belonged to patients with EPCAM 3′-end deletions. EPCAM IHC is a useful screening tool, with 100% specificity to identify LS patients due to EPCAM 3′-end deletions in MSH2-negative CRC and MSH2-negative colorectal polyps.

Diet quality and colorectal tumor risk in persons with Lynch syndrome

BACKGROUND

Persons with Lynch syndrome (LS) have an increased risk of developing colorectal tumors (CRTs). Adherence to diet quality indices associated with colorectal cancer (CRC) risk in the general population has not been studied before in LS.

METHODS

Dietary habits of 490 participants with LS from a prospective cohort study was collected using a food frequency questionnaire. The Dutch Healthy Diet index 2015 (DHD15-index) and Dietary Approaches to Stop Hypertension (DASH) were used to score food-based diet quality. Diet quality scores were divided into tertiles where a higher tertile reflects a higher diet quality. Multivariable Cox proportional hazard regression models were used to estimate the association between the DHD15-index, DASH score and CRT risk.

RESULTS

During a median follow-up time of 53.4 months, 210 participants (42.9%) developed CRTs. The DHD-index and DASH score were not associated with CRT risk; hazard ratios for highest vs. lowest tertile were 1.00 (95% Confidence Interval (CI): 0.67-1.48) and 1.11 (95% CI: 0.74-1.69), respectively. No linear trends across the DHD-index and DASH score tertiles were observed (P-trend = 0.97 and 0.83 respectively).

CONCLUSION

In contrast to observations in the general population, no evidence for an association between the food-based DHD15-index or DASH score and CRT risk was observed in persons with LS. Further studies are needed investigating the association between diet quality and mechanisms leading to the development of LS-associated tumors.

Analysis of metachronous colorectal neoplasms and survival following segmental or extended resection in patients with hereditary non-polyposis colorectal cancer

PURPOSE

The high incidence of metachronous colorectal tumours in patients with hereditary non-polyposis colorectal cancer (HNPCC) encourages extended resection (ER); however, the optimal surgical approach remains unclear. We evaluated the incidences of metachronous colorectal neoplasms following curative colorectal cancer segmental resection (SR) vs ER in patients with HNPCC and investigated patients' oncologic outcomes according to surgical modality and mismatch repair status.

METHODS

We retrospectively investigated medical records of patients with HNPCC (per the Amsterdam II criteria) treated for primary colon cancer at our institution between 2001 and 2017. All patients underwent intensive endoscopic surveillance.

RESULTS

We included 87 patients (36 who underwent SR and 51 who underwent ER). The cumulative incidence of metachronous adenoma was higher in the SR group. One patient in the SR group (2.8%) and 3 in the ER group (5.9%) developed metachronous colon cancer; the difference was not significant (P = 0.693). Four patients in the SR group (11.1%) and 1 in the ER group (2.0%) developed distant recurrences; again, the difference was not significant (P = 0.155). Moreover, no significant differences were observed in the 5-year overall survival rates of patients in the SR and ER groups (88.2% vs 95.5%, P = 0.446); the same was true for 5-year disease-free survival rates (79.5% vs 91.0%, P = 0.147).

CONCLUSION

The incidence of metachronous cancer was not significantly different between the ER and SR groups; however, that of cumulative metachronous adenoma was higher in the SR group. Hence, intensive surveillance colonoscopy may be sufficient for patients with HNPCC after non-extensive colon resection.

Yield of Lynch Syndrome Surveillance for Patients With Pathogenic Variants in DNA Mismatch Repair Genes

BACKGROUND & AIMS

Patients with Lynch syndrome are offered the same colorectal cancer (CRC) surveillance programs (colonoscopy every 2 years), regardless of the pathogenic DNA mismatch repair gene variant the patient carries. We aimed to assess the yield of surveillance for patients with these variants in MLH1, MSH2, MSH6, and PMS2.

METHODS

We analyzed data on colonoscopy surveillance, including histopathology analysis, from all patients diagnosed with Lynch syndrome (n = 264) at a single center. We compared the development of (advanced) adenomas and CRC among patients with pathogenic variants in the DNA mismatch repair genes MLH1 (n = 55), MSH2 (n = 44), MSH6 (n = 143), or PMS2 (n = 22) over 1836 years of follow-up (median follow-up of 6 years per patient).

RESULTS

At first colonoscopy, CRC was found in 8 patients. During 916 follow-up colonoscopies, CRC was found in 9 patients. No CRC was found in patients with variants in MSH6 or PMS2 over the entire follow-up period. There were no significant differences in the number of colonoscopies with adenomas or advanced adenomas among the groups. The median time of adenoma development was 3 years (IQR, 2-6 years). There were no significant differences in time to development of adenoma. However, patients with variants in MSH6 had a significant longer time to development of advanced neoplasia (advanced adenoma or CRC) than patients in the other groups. Six carriers died during follow up (5 from cancer, of which 3 from pancreatic cancer).

CONCLUSIONS

No CRC was found during follow-up of patients with Lynch syndrome carrying pathogenic variants in MSH6; advanced neoplasia developed over shorter follow-up time periods in patients with pathogenic variants in MLH1 or MSH2. The colonoscopy interval for patients with pathogenic variants in MSH6 might be increased to 3 years from the regular 2-year interval.

Associations of Pathogenic Variants in MLH1, MSH2, and MSH6 With Risk of Colorectal Adenomas and Tumors and With Somatic Mutations in Patients With Lynch Syndrome

BACKGROUND & AIMS

Lynch syndrome is caused by variants in DNA mismatch repair (MMR) genes and associated with an increased risk of colorectal cancer (CRC). In patients with Lynch syndrome, CRCs can develop via different pathways. We studied associations between Lynch syndrome-associated variants in MMR genes and risks of adenoma and CRC and somatic mutations in APC and CTNNB1 in tumors in an international cohort of patients.

METHODS

We combined clinical and molecular data from 3 studies. We obtained clinical data from 2747 patients with Lynch syndrome associated with variants in MLH1, MSH2, or MSH6 from Germany, the Netherlands, and Finland who received at least 2 surveillance colonoscopies and were followed for a median time of 7.8 years for development of adenomas or CRC. We performed DNA sequence analyses of 48 colorectal tumors (from 16 patients with mutations in MLH1, 29 patients with mutations in MSH2, and 3 with mutations in MSH6) for somatic mutations in APC and CTNNB1.

RESULTS

Risk of advanced adenoma in 10 years was 17.8% in patients with pathogenic variants in MSH2 vs 7.7% in MLH1 (P < .001). Higher proportions of patients with pathogenic variants in MLH1 or MSH2 developed CRC in 10 years (11.3% and 11.4%) than patients with pathogenic variants in MSH6 (4.7%) (P = .001 and P = .003 for MLH1 and MSH2 vs MSH6, respectively). Somatic mutations in APC were found in 75% of tumors from patients with pathogenic variants in MSH2 vs 11% in MLH1 (P = .015). Somatic mutations in CTNNB1 were found in 50% of tumors from patients with pathogenic variants in MLH1 vs 7% in MSH2 (P = .002). None of the 3 tumors with pathogenic variants in MSH6 had a mutation in CTNNB1, but all had mutations in APC.

CONCLUSIONS

In an analysis of clinical and DNA sequence data from patients with Lynch syndrome from 3 countries, we associated pathogenic variants in MMR genes with risk of adenoma and CRC, and somatic mutations in APC and CTNNB1 in colorectal tumors. If these findings are confirmed, surveillance guidelines might be adjusted based on MMR gene variants.

White-Light Endoscopy Is Adequate for Lynch Syndrome Surveillance in a Randomized and Noninferiority Study

BACKGROUND & AIMS

Dye-based pancolonic chromoendoscopy is recommended for colorectal cancer surveillance in patients with Lynch syndrome. However, there is scarce evidence to support its superiority to high-definition white-light endoscopy. We performed a prospective study assess whether in the hands of high detecting colonoscopists, high-definition, white-light endoscopy is noninferior to pancolonic chromoendoscopy for detection of adenomas in patients with Lynch syndrome.

METHODS

We conducted a parallel controlled study, from July 2016 through January 2018 at 14 centers in Spain of adults with pathogenic germline variants in mismatch repair genes (60% women; mean age, 47 ± 14 years) under surveillance. Patients were randomly assigned to groups that underwent high-definition white-light endoscopy (n = 128) or pancolonic chromoendoscopy (n = 128) evaluations by 24 colonoscopists who specialized in detection of colorectal lesions in high-risk patients for colorectal cancer. Adenoma detection rates (defined as the proportion of patients with at least 1 adenoma) were compared between groups, with a noninferiority margin (relative difference) of 15%.

RESULTS

We found an important overlap of confidence intervals (CIs) and no significant difference in adenoma detection rates by pancolonic chromoendoscopy (34.4%; 95% CI 26.4%-43.3%) vs white-light endoscopy (28.1%; 95% CI 21.1%-36.4%; P = .28). However, pancolonic chromoendoscopy detected serrated lesions in a significantly higher proportion of patients (37.5%; 95% CI 29.5-46.1) than white-light endoscopy (23.4%; 95% CI 16.9-31.4; P = .01). However, there were no significant differences between groups in proportions of patients found to have serrated lesions of 5 mm or larger (9.4% vs 7.0%; P = .49), of proximal location (11.7% vs 10.2%; P = .68), or sessile serrated lesions (3.9% vs 5.5%; P = .55), respectively. Total procedure and withdrawal times with pancolonic chromoendoscopy (30.7 ± 12.8 minutes and 18.3 ± 7.6 minutes, respectively) were significantly longer than with white-light endoscopy (22.4 ± 8.7 minutes and 13.5 ± 5.6 minutes; P < .001).

CONCLUSIONS

In a randomized parallel trial, we found that for Lynch syndrome surveillance, high-definition white-light endoscopy is not inferior to pancolonic chromoendoscopy if performed by experienced and dedicated endoscopists. ClinicalTrials.gov no: NCT02951390.

Microsatellite instability screening in colorectal adenomas to detect Lynch syndrome patients? A systematic review and meta-analysis

The colorectal cancer spectrum has changed due to population screening programs, with a shift toward adenomas and early cancers. Whether it would be a feasible option to test these adenomas for detection of Lynch syndrome (LS) patients is unclear. Through meta-analysis and systematic review, risk factors for DNA mismatch repair deficiency (dMMR) and microsatellite instability (MSI) in adenomas were identified in LS and unselected patient cohorts. Data were extracted for patient age and MMR variant together with adenoma type, grade, size, and location. A total of 41 studies were included, and contained more than 519 LS patients and 1698 unselected patients with 1142 and 2213 adenomas respectively. dMMR/MSI was present in 69.5% of conventional adenomas in LS patients, compared with 2.8% in unselected patients. In the LS cohort, dMMR/MSI was more frequently present in patients older than 60 years (82% versus 54%). dMMR/MSI was also more common in villous adenomas (84%), adenomas over 1 cm (81%), and adenomas with high grade dysplasia (88%). No significant differences were observed for dMMR/MSI in relation to MMR variants and location of adenomas. In the context of screening, we conclude that detection of dMMR/MSI in conventional adenomas of unselected patients is uncommon and might be considered as indication for LS testing. Within the LS cohort, 69.5% of LS patients could have been detected through dMMR/MSI screening of their conventional adenomas.

[Hereditary colon cancer in Lynch syndrome/HNPCC syndrome in Germany]

BACKGROUND

Hereditary nonpolyposis colorectal cancer (Lynch/HNPCC syndrome) is based on a germline mutation inducing increased occurrence of colorectal cancer and extracolonic carcinomas in young age. The German HNPCC consortium aims to increase awareness for detection of hereditary colon cancer among patients and physicians.

OBJECTIVES

Reliable detection of HNPCC patients is based on a thorough documentation of patients' medical history and on further diagnostics delivered by human genetics and surgical pathology. This manuscript presents a standardized diagnostic concept.

METHODS

Relevant literature is reviewed and discussed and diagnostic parameters are outlined. In addition, operating figures of the German HNPCC consortium are presented.

RESULTS

The German HNPCC consortium is based on an efficient cooperation between clinical physicians, human geneticists, and surgical pathologists. After a funding period from the Deutsche Krebshilfe, HNPCC diagnostics and preventive medical examinations were transferred into standard care in Germany. In total, 5770 families (8873 patients) were included in HNPCC diagnostics. To date, in 1296 families, mutations of the MLH1-, MSH2-, MSH6-, PMS2-, or EPCAM-gene have been detected. Furthermore, 612 pathogenic variants and 325 variants of unknown significance were found.

CONCLUSIONS

Reliable detection of HNPCC patients is based on a standardized diagnostic concept, which has been established within the German HNPCC consortium.

Unique MLH1 mutations in colonic adenomas in an obligate germline Lynch syndrome carrier

BACKGROUND

An obligate germline Lynch syndrome carrier had four colonic adenomas removed.

MATERIALS AND METHODS

The adenomas were evaluated for grade of dysplasia, MLH1, PMS2, MSH2 and MSH6 protein expression, microsatellite instability (MSI), BRAF, methylation status and a next-generation sequencing (NGS) panel of 52 cancer genes.

RESULTS

There were four tubular or tubulovillous adenomas from the hepatic flexure, rectosigmoid and rectum; one with low-grade and high-grade dysplasia, one with high-grade dysplasia only and two with low-grade dysplasia. All four adenomas showed retention of MLH1, MHS2 and MSH6 but complete loss of PMS2 in both low-grade and high-grade dysplasia areas.Two of the four adenomas were MSI-high, BRAF V600E wild type and were not MLH1 methylated. NGS identified an MLH1 germline variant: NM_000249.3: c.1558+1 G>A, p.(?) in all tissue (adenomas and normal), which likely explains the pathophysiology of Lynch syndrome in this patient. Other variants were also detected in MLH1 and MSH6 in all four adenomas tested; these being reported previously in somatic colorectal cancers.

CONCLUSION

We highlight an MLH1 variant in the colonic adenomas in an obligate Lynch syndrome carrier that resulted in PMS2 protein loss in the absence of mutations of the PMS2 gene.

Single-center study of Lynch syndrome screening in colorectal polyps

Background

Lynch syndrome is the most common hereditary colorectal cancer syndrome, and adenoma is one of the important premalignant lesions to colorectal cancer in Lynch syndrome. The first objective of this study was to calculate the detection rate of Lynch syndrome in colorectal polyps by using mismatch repair immunohistochemistry as the initial screening strategy. The second objective of this study was to optimize screening strategies for adenoma associated with Lynch syndrome by integrating polyp and/or patient characteristics such as polyp size, location, dysplasia, age of onset and/or family history of cancer.

Methods

From June 2014 to May 2016, immunohistochemistry was performed for mismatch repair proteins (MLH1, MSH2, MSH6, and PMS2) using endoscopically resected specimens obtained from newly diagnosed colorectal adenomas. Gene analysis was performed in patients with missing expression of mismatched repair protein.

Results

Five hundred and ten patients underwent colorectal polyp resection, with a total of 718 polyps. Five hundred and eight resected adenomas underwent mismatch repair protein immunohistochemical testing. Loss of mismatch repair protein expression was observed in six adenomas, accounting for 1.18% of all adenomas. Five patients then underwent genetic tests to identify two pathogenic mutations from different individuals, while another patient was suspected to have a pathogenic mutation. Three patients were younger than 50 years old. Two patients had advanced histology (high-grade dysplasia and malignant components) and one patient had a family history of cancer.

Conclusion

Immunohistochemical detection of colorectal polyp mismatch repair protein as Lynch syndrome screening efficiency is low. Effective screening strategies may be improved by optimizing patient/polyp selection, such as focusing on young adenoma patients with a family history of cancer, or patients who present with high-risk features (large size, villous, high-grade dysplasia and malignant components).

DNA methylation changes and somatic mutations as tumorigenic events in Lynch syndrome-associated adenomas retaining mismatch repair protein expression

Background

DNA mismatch repair (MMR) defects are a major factor in colorectal tumorigenesis in Lynch syndrome (LS) and 15% of sporadic cases. Some adenomas from carriers of inherited MMR gene mutations have intact MMR protein expression implying other mechanisms accelerating tumorigenesis. We determined roles of DNA methylation changes and somatic mutations in cancer-associated genes as tumorigenic events in LS-associated colorectal adenomas with intact MMR.

Methods

We investigated 122 archival colorectal specimens of normal mucosae, adenomas and carcinomas from 57 LS patients. MMR-deficient (MMR-D, n = 49) and MMR-proficient (MMR-P, n = 18) adenomas were of particular interest and were interrogated by methylation-specific multiplex ligation-dependent probe amplification and Ion Torrent sequencing.

Findings

Promoter methylation of CpG island methylator phenotype (CIMP)-associated marker genes and selected colorectal cancer (CRC)-associated tumor suppressor genes (TSGs) increased and LINE-1 methylation decreased from normal mucosa to MMR-P adenomas to MMR-D adenomas. Methylation differences were statistically significant when either adenoma group was compared with normal mucosa, but not between MMR-P and MMR-D adenomas. Significantly increased methylation was found in multiple CIMP marker genes (IGF2, NEUROG1, CRABP1, and CDKN2A) and TSGs (SFRP1 and SFRP2) in MMR-P adenomas already. Furthermore, certain CRC-associated somatic mutations, such as KRAS, were prevalent in MMR-P adenomas.

Interpretation

We conclude that DNA methylation changes and somatic mutations of cancer-associated genes might serve as an alternative pathway accelerating LS-associated tumorigenesis in the presence of proficient MMR.

Fund

Jane and Aatos Erkko Foundation, Academy of Finland, Cancer Foundation Finland, Sigrid Juselius Foundation, and HiLIFE.

Routine Molecular Analysis for Lynch Syndrome Among Adenomas or Colorectal Cancer Within a National Screening Program

BACKGROUND & AIMS

It is important to identify individuals with Lynch syndrome because surveillance programs can reduce their morbidity and mortality from colorectal cancer (CRC). We assessed the diagnostic yield of immunohistochemistry to detect Lynch syndrome in patients with advanced and multiple adenomas within our national CRC screening program.

METHODS

We performed a prospective study of all participants (n = 1101; 55% male; median age, 66 years; interquartile range, 61-70 years) referred to the Erasmus MC in The Netherlands after a positive result from a fecal immunohistochemical test, from December 2013 to December 2016. Colon tissues were collected from patients with advanced adenomas, ≥4 nonadvanced adenomas, or CRC, and analyzed by immunohistochemistry to identify patients with loss of mismatch repair (MMR) proteins (MLH1, MSH2, MSH6, or PMS2): a marker of Lynch syndrome. Specimens from patients with loss of MLH1 were analyzed for MLH1 promoter hypermethylation. Patients with an MMR-deficient tumor or adenoma without MLH1 promoter hypermethylation were referred for genetic analysis.

RESULTS

At colonoscopy, 456 patients (41%) (65% male; mean age, 67 years; interquartile range, 63-71 years) were found to have CRC and/or an adenoma eligible for analysis by immunohistochemistry. Of 56 CRCs, 7 (13%) had lost an MMR protein and 5 had hypermethylation of the MLH1 promoter. Analyses of tumor DNA revealed that 2 patients without MLH1 promoter hypermethylation had developed sporadic tumors. In total, 400 patients with adenomas were analyzed. Of the examined adenomas, 208 (52%) had a villous component and/or high-grade dysplasia: 186 (47%) had a villous component and 41 (10%) had high-grade dysplasia. Only 1 adenoma had lost an MMR protein. This adenoma was found to have 2 somatic mutations in MSH6.

CONCLUSIONS

In a CRC screening program in The Netherlands for individuals aged 55 to 75 years, routine screening for Lynch syndrome by immunohistochemistry analysis of colon tissues from patients with advanced and multiple adenomas identified no individuals with this genetic disorder.

No Difference in Colorectal Cancer Incidence or Stage at Detection by Colonoscopy Among 3 Countries With Different Lynch Syndrome Surveillance Policies

BACKGROUND & AIMS

Patients with Lynch syndrome are at high risk for developing colorectal cancer (CRC). Regular colonoscopic surveillance is recommended, but there is no international consensus on the appropriate interval. We investigated whether shorter intervals are associated with lower CRC incidence and detection at earlier stages by comparing the surveillance policies in Germany, which evaluates patients by colonoscopy annually, in the Netherlands (patients evaluated at 1-2-year intervals), and Finland (patients evaluated at 2-3-year intervals).

METHODS

We collected data from 16,327 colonoscopic examinations (conducted from 1984 through 2015) of 2747 patients with Lynch syndrome (pathogenic variants in the MLH1, MSH2, or MSH6 genes) from the German HNPCC Consortium, the Dutch Lynch Syndrome Registry, and the Finnish Lynch Syndrome Registry. Our analysis included 23,309 person-years of cumulative observation time. Time from the index colonoscopy to incident CRC or adenoma was analyzed using the Kaplan-Meier method; groups were compared using the log-rank test. We performed multivariable Cox regression analyses to identify factors associated with CRC risk (diagnosis of CRC before the index colonoscopy, sex, mutation, age, and presence of adenoma at the index colonoscopy).

RESULTS

The 10-year cumulative CRC incidence ranged from 4.1% to 18.4% in patients with low- and high-risk profiles, respectively, and varied with age, sex, mutation, and prior detection of CRC or adenoma. Observed colonoscopy intervals were largely in accordance with the country-specific recommendations. We found no significant differences in cumulative CRC incidence or CRC stage at detection among countries. There was no significant association between CRC stage and time since last colonoscopy.

CONCLUSIONS

We did not find a significant reduction in CRC incidence or stage of detection in Germany (annual colonoscopic surveillance) than in countries with longer surveillance intervals (the Netherlands, with 1-2-year intervals, and Finland, with 2-3-year intervals). Overall, we did not find a significant association of the interval with CRC risk, although age, sex, mutation, and prior neoplasia were used to individually modify colonoscopy intervals. Studies are needed to develop and validate risk-adapted surveillance strategies and to identify patients who benefit from shorter surveillance intervals.

Enhanced detection of microsatellite instability using pre-PCR elimination of wild-type DNA homo-polymers in tissue and liquid biopsies

Detection of microsatellite-instability in colonoscopy-obtained polyps, as well as in plasma-circulating DNA, is frequently confounded by sensitivity issues due to co-existing excessive amounts of wild-type DNA. While also an issue for point mutations, this is particularly problematic for microsatellite changes, due to the high false-positive artifacts generated by polymerase slippage (stutter-bands). Here, we describe a nuclease-based approach, NaME-PrO, that uses overlapping oligonucleotides to eliminate unaltered micro-satellites at the genomic DNA level, prior to PCR. By appropriate design of the overlapping oligonucleotides, NaME-PrO eliminates WT alleles in long single-base homopolymers ranging from 10 to 27 nucleotides in length, while sparing targets containing variable-length indels at any position within the homopolymer. We evaluated 5 MSI targets individually or simultaneously, NR27, NR21, NR24, BAT25 and BAT26 using DNA from cell-lines, biopsies and circulating-DNA from colorectal cancer patients. NaME-PrO enriched altered microsatellites and detected alterations down to 0.01% allelic-frequency using high-resolution-melting, improving detection sensitivity by 500-1000-fold relative to current HRM approaches. Capillary-electrophoresis also demonstrated enhanced sensitivity and enrichment of indels 1-16 bases long. We anticipate application of this highly-multiplex-able method either with standard 5-plex reactions in conjunction with HRM/capillary electrophoresis or massively-parallel-sequencing-based detection of MSI on numerous targets for sensitive MSI-detection.

Features of incident colorectal cancer in Lynch syndrome

Background and objective

Despite intensive colonoscopic surveillance, a substantial proportion of Lynch syndrome (LS) patients develop colorectal cancer (CRC). The aim of this study was to characterize incident CRC in LS patients.

Methods

All patients diagnosed with incident CRC after start of colonoscopic surveillance were identified in the Dutch LS Registry of 905 patients. A retrospective analysis of patient records was carried out for patient characteristics, survival, CRC characteristics and findings of previous colonoscopy.

Results

Seventy-one patients (7.8%) were diagnosed with incident CRC. Median interval between incident CRC diagnosis and previous colonoscopy was 23.8 (range 6.7-45.6) months. Median tumor diameter was 2.5 cm, and 17% of the tumors were sessile or flat. Most patients (83%) had no lymph node metastases. There was no association between tumor size and colonoscopy interval or lymph node status. Most patients (65%) had no adenomas during previous colonoscopy. Two patients (2.8%) eventually died from metastatic CRC.

Conclusion

The high frequency of incident CRC in LS likely results from several factors. Our findings lend support to the hypothesis of fast conversion of adenomas to CRC, as 65% of patients had no report of polyps during previous colonoscopy. High-quality colonoscopies are essential, especially as tumors and adenomas are difficult to detect because of their frequent non-polypoid appearance. Early detection due to surveillance as well as the indolent growth of CRC, as demonstrated by the lack of lymph node metastases, contributes to the excellent survival observed.

Polymorphisms of DNA repair genes are associated with colorectal cancer in patients with Lynch syndrome

BACKGROUND

DNA repair genes are crucial for maintaining genomic stability by preventing mutagenesis and carcinogenesis. The present retrospective cohort study aimed at investigating whether MLH1, APEX1, MUTYH, OGG1, NUDT1, XRCC5, XPA, and ERCC2 single nucleotide polymorphisms (SNPs) are associated with colorectal cancer (CRC) in Chinese population with Lynch syndrome.

METHODS

From Amsterdam criteria family registry, we identified 270 patients with Lynch syndrome. Hazard ratios (HRs) and 95% confidence intervals (CIs) for the association between DNA repair SNPs and CRC were calculated using a weighted Cox proportional hazard regression model.

RESULTS

Heterozygous variants of rs1799832 in NUDT1 (HR = 2.97, 95% CI = 1.51-5.83) and rs13181 in ERCC2 (HR = 2.69, 95% CI = 1.10-6.55) were significantly associated with an increased risk of CRC compared with wild-type homozygous CC and TT genotypes, respectively. However, the variant CG+GG genotype of MUTYH rs3219489 was associated with a decreased risk of CRC (HR = 0.49, 95% CI = 0.26-0.91) compared with the homozygous CC wild-type counterparts.

CONCLUSION

Our findings revealed that polymorphisms of DNA repair genes that include NUDT1, ERCC2, and MUTYH are associated with CRC in patients with Lynch syndrome in Chinese population. Further studies with large sample size are needed to confirm our findings.

Inflammatory potential of the diet and colorectal tumor risk in persons with Lynch syndrome

Background: Persons with Lynch syndrome (LS) have high lifetime risk of developing colorectal tumors (CRTs) because of a germline mutation in one of their mismatch repair (MMR) genes. An important process in the development of CRTs is inflammation, which has been shown to be modulated by diet.Objective: We aimed to investigate the association between the inflammatory potential of the diet and the risk of CRTs in persons with LS.Design: We used the dietary intake of 457 persons with LS from a prospective cohort study to calculate the adapted dietary inflammatory index (ADII). The ADII was split into tertiles in which the highest tertile reflects the most proinflammatory potential of the diet. Cox proportional hazard models, with robust sandwich variance estimates to adjust for dependency within families, were used to calculate HRs and 95% CIs of CRTs by ADII tertile. HRs were adjusted for age, smoking status, and education level, and number of colonoscopies as a time-dependent variable. A potential effect measure modification was explored by stratifying the results by mutated MMR gene, sex, and a history of CRTs. We performed sensitivity analyses by repeating the analyses in non-nonsteroidal anti-inflammatory drug (NSAID) users (n = 315).Results: During a median follow-up time of 59 mo, 200 participants (43.8%) developed CRTs. No significant association was shown between highest compared with lowest ADII tertiles (HR for highest compared with lowest tertiles: 1.37; 95% CI: 0.80, 2.34). Stratification by mutated MMR gene, sex, and CRT history did not show significantly differential associations (P-interactions ≥ 0.64). In non-NSAID users, an HR of 1.60 (95% CI: 0.88, 2.93) for highest compared with lowest tertiles was shown. No significant effect modification was shown in this group either (P-interactions ≥ 0.24).Conclusion: A proinflammatory potential of the diet does not seem to be significantly associated with CRT risk in persons with LS.

Colorectal cancer incidence in path_MLH1 carriers subjected to different follow-up protocols: a Prospective Lynch Syndrome Database report

Background

We have previously reported a high incidence of colorectal cancer (CRC) in carriers of pathogenic MLH1 variants (path_MLH1) despite follow-up with colonoscopy including polypectomy.

Methods

The cohort included Finnish carriers enrolled in 3-yearly colonoscopy (n = 505; 4625 observation years) and carriers from other countries enrolled in colonoscopy 2-yearly or more frequently (n = 439; 3299 observation years). We examined whether the longer interval between colonoscopies in Finland could explain the high incidence of CRC and whether disease expression correlated with differences in population CRC incidence.

Results

Cumulative CRC incidences in carriers of path_MLH1 at 70-years of age were 41% for males and 36% for females in the Finnish series and 58% and 55% in the non-Finnish series, respectively (p > 0.05). Mean time from last colonoscopy to CRC was 32.7 months in the Finnish compared to 31.0 months in the non-Finnish (p > 0.05) and was therefore unaffected by the recommended colonoscopy interval. Differences in population incidence of CRC could not explain the lower point estimates for CRC in the Finnish series. Ten-year overall survival after CRC was similar for the Finnish and non-Finnish series (88% and 91%, respectively; p > 0.05).

Conclusions

The hypothesis that the high incidence of CRC in path_MLH1 carriers was caused by a higher incidence in the Finnish series was not valid. We discuss whether the results were influenced by methodological shortcomings in our study or whether the assumption that a shorter interval between colonoscopies leads to a lower CRC incidence may be wrong. This second possibility is intriguing, because it suggests the dogma that CRC in path_MLH1 carriers develops from polyps that can be detected at colonoscopy and removed to prevent CRC may be erroneous. In view of the excellent 10-year overall survival in the Finnish and non-Finnish series we remain strong advocates of current surveillance practices for those with LS pending studies that will inform new recommendations on the best surveillance interval.

Electronic supplementary material

The online version of this article (10.1186/s13053-017-0078-5) contains supplementary material, which is available to authorized users.

Mismatch repair deficiency commonly precedes adenoma formation in Lynch Syndrome-Associated colorectal tumorigenesis

Lynch syndrome is a cancer predisposition syndrome caused by germline mutations in mismatch repair (MMR) genes. MMR deficiency is a ubiquitous feature of Lynch syndrome-associated colorectal adenocarcinomas; however, it remains unclear when the MMR-deficient phenotype is acquired during tumorigenesis. To probe this issue, the present study examined genetic alterations and MMR statuses in Lynch syndrome-associated colorectal adenomas and adenocarcinomas, in comparison with sporadic adenomas. Among the Lynch syndrome-associated colorectal tumors, 68 of 86 adenomas (79%) and all adenocarcinomas were MMR-deficient, whereas all the sporadic adenomas were MMR-proficient, as determined by microsatellite instability testing and immunohistochemistry for MMR proteins. Sequencing analyses identified APC or CTNNB1 mutations in the majority of sporadic adenomas (58/84, 69%) and MMR-proficient Lynch syndrome-associated adenomas (13/18, 72%). However, MMR-deficient Lynch syndrome-associated adenomas had less APC or CTNNB1 mutations (25/68, 37%) and frequent frameshift RNF43 mutations involving mononucleotide repeats (45/68, 66%). Furthermore, frameshift mutations affecting repeat sequences constituted 14 of 26 APC mutations (54%) in MMR-deficient adenomas whereas these frameshift mutations were rare in MMR-proficient adenomas in patients with Lynch syndrome (1/12, 8%) and in sporadic adenomas (3/52, 6%). Lynch syndrome-associated adenocarcinomas exhibited mutation profiles similar to those of MMR-deficient adenomas. Considering that WNT pathway activation sufficiently drives colorectal adenoma formation, the distinct mutation profiles of WNT pathway genes in Lynch syndrome-associated adenomas suggest that MMR deficiency commonly precedes adenoma formation.

Cancer incidence and survival in Lynch syndrome patients receiving colonoscopic and gynaecological surveillance: first report from the prospective Lynch syndrome database

OBJECTIVE

Estimates of cancer risk and the effects of surveillance in Lynch syndrome have been subject to bias, partly through reliance on retrospective studies. We sought to establish more robust estimates in patients undergoing prospective cancer surveillance.

DESIGN

We undertook a multicentre study of patients carrying Lynch syndrome-associated mutations affecting MLH1, MSH2, MSH6 or PMS2. Standardised information on surveillance, cancers and outcomes were collated in an Oracle relational database and analysed by age, sex and mutated gene.

RESULTS

1942 mutation carriers without previous cancer had follow-up including colonoscopic surveillance for 13 782 observation years. 314 patients developed cancer, mostly colorectal (n=151), endometrial (n=72) and ovarian (n=19). Cancers were detected from 25 years onwards in MLH1 and MSH2 mutation carriers, and from about 40 years in MSH6 and PMS2 carriers. Among first cancer detected in each patient the colorectal cancer cumulative incidences at 70 years by gene were 46%, 35%, 20% and 10% for MLH1, MSH2, MSH6 and PMS2 mutation carriers, respectively. The equivalent cumulative incidences for endometrial cancer were 34%, 51%, 49% and 24%; and for ovarian cancer 11%, 15%, 0% and 0%. Ten-year crude survival was 87% after any cancer, 91% if the first cancer was colorectal, 98% if endometrial and 89% if ovarian.

CONCLUSIONS

The four Lynch syndrome-associated genes had different penetrance and expression. Colorectal cancer occurred frequently despite colonoscopic surveillance but resulted in few deaths. Using our data, a website has been established at http://LScarisk.org enabling calculation of cumulative cancer risks as an aid to genetic counselling in Lynch syndrome.

TP53 Polymorphisms and Colorectal Cancer Risk in Patients with Lynch Syndrome in Taiwan: A Retrospective Cohort Study

Background and Aim

TP53 encodes p53, which has a crucial role in modulating genes that regulate defense against cancer development. This study investigated whether TP53 polymorphisms are associated with colorectal cancer (CRC) in patients with Lynch syndrome and whether TP53 interacts with lifestyle factors to modify CRC risk.

Methods

We identified 260 MLH1 and MSH2 germline mutation carriers from the Taiwan Hereditary Nonpolyposis Colorectal Cancer Consortium. A weighted Cox proportional hazard model was used to calculate hazard ratios (HRs) and 95% confidence intervals (CIs) to determine the association of TP53 polymorphisms with CRC development.

Results

The carriers of the variant C allele of rs1042522 were associated with a decreased CRC risk (GC genotype: HR = 0.35, 95% CI = 0.14–0.86; CC genotype: HR = 0.28, 95% CI = 0.13–0.57). In addition, the dominant model of rs1042522 was associated with a decreased CRC risk (HR = 0.32, 95% CI = 0.15–0.67). The CRC risk was decreased in carriers with the CT and TT genotypes of rs12947788 (HR = 0.20, 95% CI = 0.08–0.46 and HR = 0.25, 95% CI = 0.09–0.65, respectively). Moreover, the dominant model of rs12947788 was significantly associated with a decreased CRC risk (HR = 0.21, 95% CI = 0.09–0.46). A haplotype analysis indicated that compared with the most common GC haplotype, the CT haplotype was associated with a decreased CRC risk (HR = 0.26, 95% CI = 0.11–0.59). However, no significant interaction was observed between TP53 polymorphisms and lifestyle factors.

Conclusion

The study results revealed that the rs1042522 genotype with the C allele and the rs12947788 genotype with the T allele in TP53 were associated with a decreased CRC risk in patients with Lynch syndrome in Taiwan.