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

Survival of Patients with Resected Microsatellite Instability-High, Mismatch Repair Deficient, and Lynch Syndrome-Associated Pancreatic Ductal Adenocarcinomas

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) remains a challenging disease due to its aggressiveness, late-stage diagnosis, and limited treatment options. Microsatellite instability-high (MSI-H) cancers are susceptible to immune checkpoint inhibitors. Survival outcomes for patients with MSI-H PDAC are unknown as the disease is rare.

METHODS

This study included patients with PDACs surgically resected from 1990 to 2023, and those with germline or sporadic pathogenic variants in DNA mismatch repair genes were identified. The study matched MSI-H, mismatch repair-deficient (MMRd), and Lynch syndrome (LS)-associated PDAC cases (on age, gender, and year of surgery) with microsatellite-stable (MSS), mismatch repair-proficient, or non-LS-associated PDAC cases in a 1:2 ratio. A generalized estimating equation Cox model with a robust sandwich estimator was used to compare overall survival (OS) in the matched cohorts.

RESULTS

Of 936 cases, 18 were included. Eight cases were MSI-H/MMRd, two were MSI/IHC-indeterminate, seven were MSS, and one was not tested for MSI. Nine patients had LS (MLH1 [n = 1], MSH2 [n = 4], MSH6 [n = 1], PMS2 [n = 3]), and nine patients had sporadic pathogenic variants in DNA MMR genes (MLH1 [n = 4], MSH6 [n = 5]). After matching to 36 control patients, the MSI-H/MMRd/LS PDACs had a significantly better OS (hazard ratio [HR], 0.36 [95% confidence interval [CI], 0.18-0.73; p = 0.005]; 5-year OS: MSI-H 77% [95% CI 58-100%] vs. MSS 27% [95% CI 15-51%]).

CONCLUSION

Before routine use of immune checkpoint inhibitors, the patients with MSI-H, MMRd, and LS-associated PDACs displayed significantly better survival than the patients with MSS, MMR-proficient, non-LS-associated PDACs. It is expected that survival for this cohort will further improve with increased availability of immunotherapy.

Gene-specific Detection Rate of Adenomas and Advanced Adenomas in Lynch Syndrome

BACKGROUND AND AIMS

Colonoscopy is expected to reduce colorectal cancer (CRC) incidence in Lynch syndrome (LS) by detecting and removing adenomas. The existence of gene-specific differences in adenoma detection has been proposed yet remains insufficiently explored. This study aims to elucidate gene-specific adenoma detection rates and their association with post-colonoscopy CRC (PCCRC), which stands as an important issue in LS surveillance.

METHODS

In this multicenter study, we analyzed 1072 LS carriers without prior CRC undergoing surveillance colonoscopy, evaluating adenoma and advanced adenoma (AA) detection rates by gene. The primary outcome was to compare adenoma detection rates in individuals without prior CRC carrying pathogenic variants in MLH1/MSH2 vs MSH6/PMS2. Subgroup analysis was performed to assess the intermediate risk profile in MSH6 carriers relative to MLH1/MSH2 and PMS2 carriers. We compared overall adenoma detection rates, adenoma burden, age at first adenoma occurrence, and 10-year cumulative detection rates. Risk factors for AA and PCCRC were also identified. Multiple testing and multivariate analyses were performed.

RESULTS

The adenoma detection rates were similar across the 4 genes. However, MLH1/MSH2 carriers had a higher overall AA detection rate compared with MSH6/PMS2 carriers (14.5% vs 11.9%; P = .04) and showed higher cumulative AA detection rates over 10 years (21.6% vs 19.7%; P = .04). Subgroup analysis indicated that MSH6 carriers had an intermediate AA detection rate positioned between MLH1/MSH2 carriers and PMS2 carriers. Multivariate analysis indicated that AAs (odds ratio, 2.12; 95% confidence interval, 1.08-4.17; P=.03) and repeated AA detection (odds ratio, 4.62; 95% confidence interval, 1.70-12.57; P < .01) were independent risk factors for PCCRC.

CONCLUSIONS

Carriers of MLH1/MSH2 pathogenic variants are at a higher risk of developing AAs compared with those with MSH6/PMS2 mutations, with MSH6 carriers exhibiting an intermediate risk profile. AAs are an independent risk factor for PCCRC. LS patients with AAs should be identified as high risk and undergo enhanced colonoscopy surveillance.

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.

Colorectal Neoplasia Detection Rates in Lynch Syndrome

BACKGROUND

The expected and optimal adenoma detection rate (ADR) is not well characterized in Lynch syndrome (LS). The aim of this study is to determine the ADR, the overall colorectal neoplasia detection rate (CNDR), proximal serrated detection rate (PSDR), and CRC detection rate (CRCDR) in an LS cohort.

METHODS

A retrospective study was performed of individuals with LS who were evaluated at a single tertiary care center from May 2001 to September 2023 (n = 542). Data from procedure and pathology reports were collected along with relevant demographic, clinical history, and family history data. Fisher's exact test and the Kruskal-Wallis test were used to assess factors associated with colorectal neoplasia.

RESULTS

Amongst 542 individuals with LS, 352 met the inclusion criteria, and their 1296 colonoscopies/sigmoidoscopies were used for analysis. The cohort was primarily female (64.5%), white (87.5%), and privately insured (76.1%), with a near even distribution across genotypes. CNDR was 27.9%, ADR was 21.4%, PSDR was 7.7%, and CRCDR was 1.5%. Advanced age, Medicare insurance, prior colonic resection, and prior history of non-CRC were significantly associated with an increased CNDR and ADR (p < 0.05). PSDR remained constant with age. There was no association with genotype, biological sex, race, smoking, BMI, aspirin use, nor family history.

CONCLUSIONS

Despite frequent colonoscopies/sigmoidoscopies, individuals with LS maintain a high rate of colorectal neoplasia, primarily driven by increased detection of adenomas with advancing age. Neoplasia rates may serve as helpful "ballpark rates" for endoscopists performing colonoscopies/sigmoidoscopies in LS. However, further studies need to determine whether neoplasia rates are predictive of CRC risk and outcomes in LS.

Colonoscopic surveillance in Lynch syndrome: guidelines in perspective

Lynch syndrome predisposes to a high risk of colorectal cancer and colonoscopy remains the primary preventive strategy. The prevention of colorectal cancer through colonoscopy relies on identifying and removing adenomas, the main precursor lesion. Nevertheless, colonoscopy is not an optimal strategy since post-colonoscopy colorectal cancer remains an important issue. In continuation of a 2021 journal review, the present article seeks to offer an updated perspective by examining relevant articles from the past 3 years. We place recent findings in the context of existing guidelines, with a specific focus on colonoscopy surveillance. Key aspects explored include colonoscopy quality standards, timing of initiation, and surveillance intervals. Our review provides a comprehensive analysis of adenoma-related insights in Lynch syndrome, delving into emerging technologies like virtual chromoendoscopy and artificial intelligence-assisted endoscopy. This review aims to contribute valuable insights into the topic of colonoscopy surveillance in Lynch syndrome.

Complications of colonoscopy surveillance of patients with Lynch syndrome - 33 years of follow up

BACKGROUND AND STUDY AIMS

Lynch syndrome (LS) is a hereditary autosomal dominant condition, with an increased lifetime risk of developing malignancies including colorectal cancer (CRC). Current guidelines differ in recommended colonoscopy-surveillance intervals from 1 to 2 years. Although colonoscopy is considered a safe procedure, there are risks of severe adverse events (SAEs), such as perforation and bleeding, as well as adverse events (AEs), such as abdominal discomfort and post-colonoscopy gastrointestinal infections. Colonoscopy-related bleeding and perforation rates have been reported 0.17% and 0.11%, respectively. However, there are insufficient data regarding complications of colonoscopy-surveillance for LS patients. This study aims to investigate the risk of AEs among LS patients during colonoscopy in the Stockholm region.

PATIENTS AND METHODS

This retrospective cohort study includes 351 LS patients undergoing endoscopic surveillance at the Karolinska University Hospital, August 1989 - April 2021. Data from endoscopic surveillance colonoscopies were extracted from patients' medical records.

RESULTS

Of 1873 endoscopies in 351 LS patients, 12 complications (AEs) were documented within 30 days (0.64%) and with a total of 3 bleedings (SAEs, 0.16%). No perforations were identified.

CONCLUSION

Colonoscopy surveillance for LS patients shows a comparatively low risk of AEs per-examination. Colonoscopy complications per-patient, including both SAEs and AEs, show a significantly higher risk. Colonoscopy complications only including SAEs, show a comparatively low risk. Understanding the lifetime risk of surveillance-related colonoscopy complications is important when designing targeted surveillance programmes.

Colonoscopy and Upper Endoscopy Surveillance in Lynch Syndrome: A Longitudinal Study From a Large Tertiary Healthcare System

Background and Aims

Lynch syndrome (LS) is caused by pathogenic mutations in mismatch repair (MMR) genes. There are limited data on differences in colorectal cancer (CRC) surveillance by MMR genes, and an international consensus on surveillance based on genes is not established. We aimed to evaluate colonoscopy and esophagogastroduodenoscopy (EGD) surveillance outcomes and compare CRC surveillance findings by the mutated gene.

Methods

One hundred one patients with LS were included and colonoscopy results were compared by MMR mutation. Primary outcomes included the development and recurrence of adenoma, CRC, high-grade dysplasia, advanced adenoma, and sessile serrated lesions. Logistic regressions evaluated the relationship between genes and the development or recurrence of primary outcomes. Survival analysis evaluated primary outcomes in patients with ≥ 2 colonoscopies. EGD results were summarized.

Results

Three hundred twenty seven colonoscopies were reviewed. Compared to PMS2, MLH1 was associated with a higher risk of advanced adenoma/high-grade dysplasia/CRC development (odds ratio [OR] 9.85, 95% confidence interval [CI]: 1.97-77.24) and MSH2 was associated with a higher risk of adenoma development (OR 4.17, 95% CI: 1.11-17.61). Among those with > 2 colonoscopies, MLH1 (hazard ratio 18.98, 95% CI: 1.31-274.51) and MSH6 (hazard ratio 15.03, 95% CI: 1.16-194.65) had a higher risk of sessile serrated lesions compared to MSH2. Among patients who had adenoma detected once, MLH1 had a higher risk of adenoma recurrence compared to MSH6 (OR 14.59, 95% CI: 1.53-244.30) and PMS2 (OR 47.15, 95% CI: 4.26-984.28). MSH2 had a higher risk of adenoma recurrence compared to PMS2 (OR 11.89, 95% CI: 1.38-164.78). Of 170 EGDs, an actionable finding was identified in 16% of patients during their first 3 EGDs.

Conclusion

Surveillance colonoscopy outcomes differed in patients with LS and suggest the need to guide surveillance based on MMR gene mutation.

Emerge of colorectal cancer in Lynch syndrome despite colonoscopy surveillance: A challenge of hide and seek

Even with colonoscopy surveillance, Lynch syndromes (LS) carriers still develop colorectal cancer (CRC). The cumulative incidence of CRCs under colonoscopy surveillance varies depending on the affected mismatch repair (MMR) gene. However, the precise mechanisms driving these epidemiological patterns remain incompletely understood. In recent years, several potential mechanisms explaining the occurrence of CRCs during colonoscopy surveillance have been proposed in individuals with and without LS. These encompass biological factors like concealed/accelerated carcinogenesis through a bypassed adenoma stage and accelerated progression from adenomas. Alongside these, various colonoscopy-related factors may contribute to formation of CRCs under colonoscopy surveillance, like missed yet detectable (pre)cancerous lesions, detected yet incompletely removed (pre)cancerous lesions, and colonoscopy-induced carcinogenesis due to tumor cell reimplantation. In this comprehensive literature update, we reviewed these potential factors and evaluated their relevance to each MMR group in an attempt to raise further awareness and stimulate research regarding this conflicting phenomenon.

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.

Metachronous colorectal cancer risk according to Lynch syndrome pathogenic variant after extensive versus partial colectomy in the Netherlands: a retrospective cohort study

BACKGROUND

Extensive colectomy (subtotal or total colectomy) is often advised for carriers of Lynch syndrome with colorectal cancer. However, the risk of metachronous colorectal cancer might differ by Lynch syndrome variant, meaning that partial colectomy, which has better functional outcomes, might be adequate for some patients with low-risk variants. We aimed to assess the risk of metachronous colorectal cancer after partial colectomy and extensive colectomy in carriers of Lynch syndrome with different pathogenic variants.

METHODS

For this retrospective cohort study, carriers of Lynch syndrome with colorectal cancer in the Netherlands were identified by linkage of the Dutch Foundation for the Detection of Hereditary Tumors (StOET) database and the Dutch Nationwide Network and Registry of Histopathology and Cytopathology (PALGA) database. Data on demographics, Lynch syndrome variants, colorectal cancers, surgery types, mortality, and surveillance colonoscopies were extracted. Data on colorectal cancer and surveillance colonoscopies were updated until Feb 28, 2022. Data on survival status was updated until Feb 7, 2022. MLH1, MSH2, and EPCAM were classified as high-risk variants and MSH6 and PMS2 as low-risk variants. Patients for whom the type of surgery was unknown were excluded. Cox regression time-to-event analyses were done to assess the risk of metachronous colorectal cancer in four subgroups based on pathogenic variant (high-risk vs low-risk variants) and the extent of surgery (extensive colectomy vs partial colectomy). Sex, age at the time of primary colorectal cancer, primary colorectal cancer stage, performance of surveillance colonoscopies, adherence to the surveillance guidelines, and time period of primary colorectal cancer diagnosis were added to the model as possible confounders. Metachronous colorectal cancer was defined as colorectal cancer diagnosed more than 6 months after the primary colorectal cancer. Patients were censored at time of death or assembly of the database.

FINDINGS

Of 1908 carriers of Lynch syndrome registered in StOET, 532 with a history of colorectal cancer were identified after linkage with PALGA. Five carriers were excluded because of an unknown surgery type, leaving 527 in our sample (mean age at primary colorectal cancer 48·7 years [SD 12·1]; 274 [52%] male and 253 [48%] female). 121 (23%) patients developed metachronous colorectal cancer (median time from primary colorectal cancer to metachronous colorectal cancer 11·0 years [IQR 2·1-17·8]). Metachronous colorectal cancer occurred in 12 (12%) of 97 patients with high-risk variants and extensive colectomy, in 85 (32%) of 267 patients with high-risk variants and partial colectomy, in zero (0%) of 11 patients with low-risk variants and extensive colectomy, and in 24 (16%) of 152 patients with low-risk variants and partial colectomy. Partial colectomy was associated with a higher risk of metachronous colorectal cancer than extensive colectomy in the high-risk variant group (hazard ratio 1·97, 95% CI 1·04-3·73; p=0·039). The risk of metachronous colorectal cancer did not differ between carriers of low-risk variants who had partial colectomy and those of high-risk variants who had extensive colectomy (1·14, 0·55-2·36; p=0·72).

INTERPRETATION

The risk of metachronous colorectal cancer after partial colectomy in carriers of low-risk variants is similar to the risk after extensive colectomy in carriers of high-risk variants. This finding suggests that partial colectomy followed by endoscopic surveillance is an appropriate management approach to treat colorectal cancer in carriers of low-risk Lynch syndrome variants.

FUNDING

None.

Incidence and prevalence of advanced colorectal neoplasia in Lynch syndrome

BACKGROUND AND AIMS

Lynch syndrome (LS) is the most common hereditary cause of colorectal cancer (CRC) and endometrial cancer (EC). Although colonoscopy reduces CRC in LS, the protection is variable. We assessed the prevalence and incidence of neoplasia in LS during surveillance colonoscopy in the United States and factors associated with advanced neoplasia.

METHODS

Patients with LS undergoing ≥1 surveillance colonoscopy and with no personal history of invasive CRC or colorectal surgery were included. Prevalent and incident neoplasia was defined as occurring <6 months before and ≥6 months after germline diagnosis of LS, respectively. We assessed advanced adenoma (AA), CRC, and the impact of mismatch repair pathogenic variant (PV) and typical LS cancer history (personal history of EC and/or family history of EC/CRC) on outcome.

RESULTS

A total of 132 patients (inclusive of 112 undergoing prevalent and incident surveillance) were included. The median examination interval and duration of prevalent and incident surveillance was .88 and 1.06 years and 3.1 and 4.6 years, respectively. Prevalent and incident AA were detected in 10.7% and 6.1% and invasive CRC in 0% and 2.3% of patients. All incident CRC occurred in MSH2 and MLH1 PV carriers and only 1 (.7%) while under surveillance in our center. AAs were detected in both LS cancer history cohorts and represented in all PVs.

CONCLUSIONS

In a U.S. cohort of LS, advanced neoplasia rarely occurred over annual surveillance. CRC was diagnosed only in MSH2/MLH1 PV carriers. AAs occurred regardless of PV or LS cancer history. Prospective studies are warranted to confirm our findings.

Endoscopic surveillance of Lynch syndrome at a highly specialized center in Sweden: An observational study of interval colorectal cancer and individual risk factors

Introduction

Lynch syndrome (LS) is the most common hereditary cause of colorectal cancer (CRC). In order to detect CRCs amongst LS patients, regular colonoscopies are recommended. However, an international agreement on an optimal surveillance interval has not yet been reached. In addition, few studies have investigated factors that could potentially increase the CRC risk amongst LS patients.

Aims

The primary aim was to describe the frequency of CRCs detected during endoscopic surveillance and to estimate the interval from a clean colonoscopy to CRC detection amongst LS patients. The secondary aim was to investigate individual risk factors, including sex, LS genotype, smoking, aspirin use and body mass index (BMI), on CRC risk amongst patients that develop CRC before and during surveillance.

Material and methods

Clinical data and colonoscopy findings from 366 LS patients' 1437 surveillance colonoscopies were collected from medical records and patient protocols. Logistic regression and Fisher's exact test were used to investigate associations between individual risk factors and CRC development. Mann-Whitney U test was used to compare the distribution of TNM stages of CRC detected before surveillance and after index.

Results

CRC was detected in 80 patients before surveillance and in 28 patients during surveillance (10 at index and 18 after index). During the surveillance programme, CRC was detected within 24 months in 65% of the patients, and after 24 months within 35% of the patients. CRC was more common amongst men, previous and current smokers, and the odds of developing CRC also increased with an increasing BMI. CRCs were more often detected amongst MLH1 and MSH2 carriers during surveillance, compared to the other genotypes.

Conclusions

We found that 35% of the CRC cases detected during surveillance were found after 24 months. MLH1 and MSH2 carriers were at higher risk of developing CRC during surveillance. Additionally, men, current or previous smokers, and patients with a higher BMI were at higher risk of developing CRC. Currently, LS patients are recommended a "one-size-fits-all" surveillance program. The results support the development of a risk-score whereby individual risk factors should be taken into consideration when deciding on an optimal surveillance interval.

Real-time use of artificial intelligence (CADEYE) in colorectal cancer surveillance of patients with Lynch syndrome-A randomized controlled pilot trial (CADLY)

BACKGROUND

Lynch syndrome (LS), an autosomal dominant disorder caused by pathogenic germline variants in DNA mismatch repair (MMR) genes, represents the most common hereditary colorectal cancer (CRC) syndrome. Lynch syndrome patients are at high risk of CRC despite regular endoscopic surveillance.

OBJECTIVE

Our aim was to investigate the diagnostic performance of artificial intelligence (AI)-assisted colonoscopy in comparison to High-Definition white-light endoscopy (HD-WLE) for the first time.

METHODS

Patients ≥18 years with LS, with a pathogenic germline variant (MLH1, MHS2, MSH6), and at least one previous colonoscopy (interval 10-36 months) were eligible. Patients were stratified by previous CRC and affected MMR gene with a 1:1 allocation ratio (AI-assisted vs. HD white-light endoscopy) in this exploratory pilot trial.

RESULTS

Between Dec-2021 and Dec-2022, 101 LS patients were randomised and 96 patients were finally analyzed after exclusion of 5 patients due to insufficient bowel preparation. In the HD-WLE arm, adenomas were detected in 12/46 patients compared to 18/50 in the AI arm (26.1% [95% CI 14.3-41.1] vs. 36.0% [22.9-50.8]; p = 0.379). The use of AI-assisted colonoscopy especially increased detection of flat adenomas (Paris classification 0-IIb) (examinations with detected flat adenomas: 3/46 [6.5%] vs. 10/50 [20%]; p = 0.07; numbers of detected flat adenomas: 4/20 vs. 17/30, p = 0.018). The median withdrawal time did not differ significantly between HD-WLE and AI (14 vs. 15 min; p = 0.170).

CONCLUSION

We here present first data suggesting that real-time AI-assisted colonoscopy is a promising approach to optimize endoscopic surveillance in LS patients, in particular to improve the detection of flat adenomas.

Quality of Colonoscopy Is Associated With Adenoma Detection and Postcolonoscopy Colorectal Cancer Prevention in Lynch Syndrome

BACKGROUND & AIMS

Colonoscopy reduces colorectal cancer (CRC) incidence and mortality in Lynch syndrome (LS) carriers. However, a high incidence of postcolonoscopy CRC (PCCRC) has been reported. Colonoscopy is highly dependent on endoscopist skill and is subject to quality variability. We aimed to evaluate the impact of key colonoscopy quality indicators on adenoma detection and prevention of PCCRC in LS.

METHODS

We conducted a multicenter study focused on LS carriers without previous CRC undergoing colonoscopy surveillance (n = 893). Incident colorectal neoplasia during surveillance and quality indicators of all colonoscopies were analyzed. We performed an emulated target trial comparing the results from the first and second surveillance colonoscopies to assess the effect of colonoscopy quality indicators on adenoma detection and PCCRC incidence. Risk analyses were conducted using a multivariable logistic regression model.

RESULTS

The 10-year cumulative incidence of adenoma and PCCRC was 60.6% (95% CI, 55.5%-65.2%) and 7.9% (95% CI, 5.2%-10.6%), respectively. Adequate bowel preparation (odds ratio [OR], 2.07; 95% CI, 1.06-4.3), complete colonoscopies (20% vs 0%; P = .01), and pan-chromoendoscopy use (OR, 2.14; 95% CI, 1.15-3.95) were associated with significant improvement in adenoma detection. PCCRC risk was significantly lower when colonoscopies were performed during a time interval of less than every 3 years (OR, 0.35; 95% CI, 0.14-0.97). We observed a consistent but not significant reduction in PCCRC risk for a previous complete examination (OR, 0.16; 95% CI, 0.03-1.28), adequate bowel preparation (OR, 0.64; 95% CI, 0.17-3.24), or previous use of high-definition colonoscopy (OR, 0.37; 95% CI, 0.02-2.33).

CONCLUSIONS

Complete colonoscopies with adequate bowel preparation and chromoendoscopy use are associated with improved adenoma detection, while surveillance intervals of less than 3 years are associated with a reduction of PCCRC incidence. In LS, high-quality colonoscopy surveillance is of utmost importance for CRC prevention.

Colorectal Cancer Screening Recommendations and Outcomes in Lynch Syndrome

Screening for colorectal cancer (CRC) in Lynch syndrome enables early detection and likely cancer prevention. CRC screening guidelines have evolved from universal to gene-specific recommendations based on lifetime neoplasia risks. Regular screening for Lynch syndrome reduces CRC-related mortality; however, high CRC incidence during regular colonoscopy screening suggests the possibility of nonpolypoid carcinogenesis. Colonoscopy is the primary modality for screening for Lynch syndrome with mixed and emerging data on quality metrics, chromoendoscopy, artificial intelligence, and nonendoscopic modalities. Screening adherence varies across studies. In this review, we present the current state of CRC screening recommendations, outcomes, and modalities in Lynch syndrome.

Gene-Specific Variation in Colorectal Cancer Surveillance Strategies for Lynch Syndrome

BACKGROUND AND AIMS

Lynch syndrome is associated with pathogenic variants in 4 mismatch repair (MMR) genes that increase lifetime risk of colorectal cancer. Guidelines recommend intensive colorectal cancer surveillance with colonoscopy every 1-2 years starting at age 25 years for all carriers of Lynch syndrome-associated variants, regardless of gene product. We constructed a simulation model to analyze the effects of different ages of colonoscopy initiation and surveillance intervals for each MMR gene (MLH1, MSH2, MSH6, and PMS2) on colorectal cancer incidence and mortality, quality-adjusted life-years, and cost.

METHODS

Using published literature, we developed a Markov simulation model of Lynch syndrome progression for patients with each MMR variant. The model simulated clinical trials of Lynch syndrome carriers, varying age of colonoscopy initiation (5-year increments from 25-40 years), and surveillance intervals (1-5 years). We assessed the optimal strategy for each gene, defined as the strategy with the highest quality-adjusted life-years and incremental cost-effectiveness ratio below a $100,000 willingness-to-pay threshold.

RESULTS

Optimal surveillance for patients with pathogenic variants in the MLH1 and MSH2 genes was colonoscopy starting at age 25 years, with 1- to 2-year surveillance intervals. Initiating colonoscopy at age 35 and 40 years, with 3-year intervals, was cost-effective for patients with pathogenic variants in MSH6 or PMS2, respectively.

CONCLUSIONS

We developed a simulation model to select optimal surveillance starting ages and intervals for patients with Lynch syndrome based on MMR variant. The model supports recommendations for intensive surveillance of patients with Lynch syndrome-associated variants in MLH1 or MSH2. However, for patients with Lynch syndrome-associated variants of MSH6 or PMS2, later initiation of surveillance at 35 and 40 years, respectively, and at 3-year intervals, can be considered.

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.

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.

Associations Between Mutations in MSH6 and PMS2 and Risk of Surveillance-detected Colorectal Cancer

BACKGROUND & AIMS

Lynch syndrome is the most common inherited cause of colorectal cancer (CRC). Contemporary and mutation-specific estimates of CRC-risk in patients undergoing colonoscopy would optimize surveillance strategies. We performed a prospective national cohort study, using data from New Zealand, to assess overall and mutation-specific risk of CRC in patients with Lynch syndrome undergoing surveillance.

METHODS

We performed a prospective study of 381 persons with Lynch syndrome in New Zealand (98 with Lynch-syndrome associated variants in MLH1, 159 in MSH2, 103 in MSH6, and 21 in PMS2). Participants were offered annual colonoscopy starting at age 25 y, and those who underwent 2 or more colonoscopies before December 31, 2017 were included in the final analysis. Patients with previous colonic resection, history of CRC or diagnosis of CRC at index colonoscopy were excluded.

RESULTS

Study participants underwent 2061 colonoscopies during 2296 person-y; the median observation-period was 4.43 y and mean-age at enrollment was 43 y. Eighteen patients developed CRC (8 with variants in MLH1, 8 in MSH2, and 2 in MSH6) after a median follow-up period of 6.5 y (range 1-16 y). Eighty-three percent of patients had a surveillance colonoscopy in preceding 24 months before diagnosis of CRC; 94% were diagnosed with stage 0-II CRC and there was no CRC-related mortality. The overall-risk of developing CRC in the 5 y after first surveillance colonoscopy was 2.49% (95% CI, 1.18-5.23); cumulative risks for CRC in patients with Lynch syndrome-associated variants in MLH1, MSH2, or MSH6 by age 70 y were 17.7%, 17.8%, and 8.5%, respectively. Age-adjusted CRC-risk in patients with variants in MSH6 was lower than in MLH1 (hazard ratio, 0.2; 95% CI, 0.04-0.94; P = .02). Of patients with CRC, 33% had an adenomatous polyp resected from same segment in which a colorectal tumor later developed.

CONCLUSIONS

The risk of CRC in patients with Lynch syndrome-associated mutations in MSH6 or PMS2 was significantly lower than in patients with mutations in MLH1. Incomplete adenomatous polyp resection might be responsible for one third of surveillance-detected CRCs.

Cost-effectiveness analysis of genetic diagnostic strategies for Lynch syndrome in Italy

Lynch syndrome (LS) is an autosomal dominant condition caused by pathogenic variants in mismatch repair (MMR) genes that predispose individuals to different malignancies, such as colorectal cancer (CRC) and endometrial cancer. Current guidelines recommended testing for LS in individuals with newly diagnosed CRC to reduce cancer morbidity and mortality in relatives. Economic evaluations in support of such approach, however, are not available in Italy. We developed a decision-analytic model to analyze the cost-effectiveness of LS screening from the perspective of the Italian National Health System. Three testing strategies: the sequencing of all MMR genes without prior tumor analysis (Strategy 1), a sequential IHC and MS-MLPA analysis (Strategy 2), and an age-targeted strategy with a revised Bethesda criteria assessment before IHC and methylation-specific MLPA for patients ≥ than 70 years old (Strategy 3) were analyzed and compared to the “no testing” strategy. Quality Adjusted Life Years (QALYs) in relatives after colonoscopy, aspirin prophylaxis and an intensive gynecological surveillance were estimated through a Markov model. Assuming a CRC incidence rate of 0.09% and a share of patients affected by LS equal to 2.81%, the number of detected pathogenic variants among CRC cases ranges, in a given year, between 910 and 1167 depending on the testing strategy employed. The testing strategies investigated, provided one-time to the entire eligible population (CRC patients), were associated with an overall cost ranging between €1,753,059.93-€10,388,000.00. The incremental cost-effectiveness ratios of the Markov model ranged from €941.24 /QALY to €1,681.93 /QALY, thus supporting that “universal testing” versus “no testing” is cost-effective, but not necessarily in comparison with age-targeted strategies. This is the first economic evaluation on different testing strategies for LS in Italy. The results might support the introduction of cost-effective recommendations for LS screening in Italy.

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.