Worldwide prevalence of Lynch syndrome in patients with colorectal cancer: Systematic review and meta-analysis

Lynch Syndrome Screening and Surveillance Trends among Gastroenterologists in Japan: A Questionnaire Survey-based Analysis

Objective Screening and surveillance methodologies for Lynch syndrome (LS) in Japan. This study assessed the changes in LS knowledge and practice trends. Methods In 2020 and 2022, 2 questionnaire surveys were administered to 3,574 councilors of the Japanese Society of Gastroenterology to assess changes in LS-related knowledge and practices. Materials Each questionnaire item was analyzed by comparing responses between the first and second surveys to determine the proportion of doctors selecting each option relative to the total number of respondents. The responses from doctors who completed both surveys were analyzed to assess the temporal changes in their responses. Results The second survey showed a significant increase in the awareness of universal tumor screening (UTS), proportion of doctors selecting UTS for primary LS screening, use of BRAF V600E testing for chemotherapy selection, and number of newly diagnosed LS patients per doctor over the last three years. In addition, the number of patients currently under surveillance by doctors has also increased. Doctors who intensified primary screening for LS between surveys reported a greater increase in newly diagnosed cases. However, the rise in UTS suggests a potential bias from doctors with heightened interest in LS, which may have influenced the findings. Conclusion The number of newly diagnosed and currently monitored patients with LS in Japan has been increasing, likely due to expanded screening practices. However, the potential bias introduced by the increased adoption of UTS should be considered when interpreting these results.

Genomics and integrative clinical data machine learning scoring model to ascertain likely Lynch syndrome patients

BACKGROUND

Lynch syndrome (LS) screening methods include multistep molecular somatic tumor testing to distinguish likely-LS patients from sporadic cases, which can be costly and complex. Also, direct germline testing for LS for every diagnosed solid cancer patient is a challenge in resource limited settings. We developed a unique machine learning scoring model to ascertain likely-LS cases from a cohort of colorectal cancer (CRC) patients.

METHODS

We used CRC patients from the cBioPortal database (TCGA studies) with complete clinicopathologic and somatic genomics data. We determined the rate of pathogenic/likely pathogenic variants in five (5) LS genes (MLH1, MSH2, MSH6, PMS2, EPCAM), and the BRAF mutations using a pre-designed bioinformatic annotation pipeline. Annovar, Intervar, Variant Effect Predictor (VEP), and OncoKB software tools were used to functionally annotate and interpret somatic variants detected. The OncoKB precision oncology knowledge base was used to provide information on the effects of the identified variants. We scored the clinicopathologic and somatic genomics data automatically using a machine learning model to discriminate between likely-LS and sporadic CRC cases. The training and testing datasets comprised of 80% and 20% of the total CRC patients, respectively. Group regularisation methods in combination with 10-fold cross-validation were performed for feature selection on the training data.

RESULTS

Out of 4800 CRC patients frorm the TCGA datasets with clinicopathological and somatic genomics data, we ascertained 524 patients with complete data. The scoring model using both clinicopathological and genetic characteristics for likely-LS showed a sensitivity and specificity of 100%, and both had the maximum accuracy, area under the curve (AUC) and AUC for precision-recall (AUCPR) of 1. In a similar analysis, the training and testing models that only relied on clinical or pathological characteristics had a sensitivity of 0.88 and 0.50, specificity of 0.55 and 0.51, accuracy of 0.58 and 0.51, AUC of 0.74 and 0.61, and AUCPR of 0.21 and 0.19, respectively.

CONCLUSIONS

Simultaneous scoring of LS clinicopathological and somatic genomics data can improve prediction and ascertainment for likely-LS from all CRC cases. This approach can increase accuracy while reducing the reliance on expensive direct germline testing for all CRC patients, making LS screening more accessible and cost-effective, especially in resource-limited settings.

Mismatch Repair Proficient Colorectal Adenocarcinoma in Two Patients With Lynch Syndrome

Screening for Lynch syndrome (LS) is essential in colorectal carcinoma (CRC) diagnosis. The hallmark of CRC in LS is mismatch repair (MMR) deficiency, a vital biomarkers assessed by microsatellite instability (MSI) analysis and/or immunohistochemistry (IHC) staining of the MMR proteins in the tumor, that also predict response to immune checkpoint inhibitors. We report two LS patients who developed MMR proficient CRCs. Patient A, with a pathogenic MSH6 germline variant, presented with two MMR discordant CRCs: a rectal MMRd/MSI adenocarcinoma, and a sigmoid MMR proficient (MMRp) and microsatellite stable (MSS) adenocarcinoma, leading to metastasis. While the MMRd/MSI carcinoma was recognized early and showed complete pathologic response after pembrolizumab treatment, the MMRp/MSS adenocarcinoma was underrecognized and poorly responsive to treatment. A second patient, with a pathogenic PMS2 variant, also developed a MMRp CRC. These cases highlight the complex biological pathways in CRC development and the impact of molecular classification on treatment.

Renal mucinous cystadenoma in the context of lynch syndrome and colonic neuroendocrine neoplasm: a case report

Renal mucinous cystadenoma (RMC) is an exceptionally rare finding with a poorly understood pathogenesis. Links between RMC and other malignancies are not well described, nor are there known associations with familial cancer disorders. We present the first case of RMC associated with Lynch syndrome (LS) and neuroendocrine neoplasm. A 56-year-old woman presented with iron deficiency leading to a diagnosis of a colonic mixed neuroendocrine-non-neuroendocrine carcinoma. After initial surgery, she experienced local recurrences at 6 and 12 months, treated with resection and adjuvant chemotherapy. Tumours displayed deficient MMR proteins with BRAF positivity, and germline testing confirmed LS. Surveillance subsequently revealed a complex cyst arising from a horseshoe kidney, for which she underwent a partial nephrectomy. Histopathology confirmed this to be renal mucinous cystadenoma arising from the pelvicalyceal system. This case underscores the need for further investigation into RMC pathogenesis and its potential association with LS.

Epidemiology of colorectal cancer: A review with special emphasis on India

Colorectal cancer (CRC) is a common malignancy and cause for death around the world. In India, it ranks as the fourth most incident cancer in both sexes, with 64,863 cases and 38,367 deaths in 2022. With such high mortality, CRC survival in India is way lesser than that of developed countries. While western countries are facing an overall decline in CRC incidence, various regions in India are seeing an increasing trend. Within India, urban regions have markedly higher incidence than rural. Risk factors include consumption of red and processed meat, fried and sugary food, smoking and alcohol, comorbidities such as obesity, diabetes and inflammatory bowel disease (IBD), family history of CRC, adenomas and genetic syndromes, radiation exposure, pesticides and asbestos. Consumption of nutrient-rich well-balanced diets abundant in vegetables, dairy products, whole grains, nuts and legumes combined with physical activity are protective against CRC. Besides these, metformin, aspirin and micronutrient supplements were inversely associated with the development of CRC. Since a considerable proportion of CRC burden is attributed to modifiable risk factors, execution of population level preventive strategies is essential to limit the growing burden of CRC. Identifying the necessity, in this review, we explore opportunities for primary prevention and for identifying high-risk populations of CRC to control its burden in the near future.

Advances in diagnostic and therapeutic applications of mismatch repair loss in cancer

Mismatch repair (MMR) is a highly conserved, fundamental DNA damage repair pathway that maintains genomic fidelity during cell replication. MMR dysregulation contributes to tumor formation by promoting genomic instability thereby increasing the frequency of potentially oncogenic mutational events. Therefore, MMR dysregulation, in its tumor suppressor role, is largely studied in the context of genomic instability and associated response to immune checkpoint blockade therapies. However, a growing body of literature suggests that the impact of MMR dysregulation on tumor phenotypes is more nuanced than a concerted impact on genomic stability. Rather, loss of individual MMR genes promotes distinct cancer-relevant biological phenotypes, and these phenotypes are further modulated by the tissue of tumor origin. Here, we explore relevant literature and review the prognostic and predictive significance of these non-canonical discoveries.

Genomic Landscapes of Early-Onset Versus Average-Onset Colorectal Cancer Populations

BACKGROUND

Rates of early-onset colorectal cancer (eoCRC), defined as disease diagnosed at <50 years of age, are increasing. The incidence and spectrum of somatic and pathogenic germline variants (PGV) in this population are not well understood.

METHODS

This cross-sectional study leveraged Tempus' clinicogenomic database, including de-identified records of patients diagnosed with CRC between 2000-2022, to analyze and compare eoCRC and average-onset colorectal cancer (aoCRC, disease diagnosed ≥50 years of age) patients. The frequency and spectrum of somatic mutations and PGVs in patients with eoCRC and aoCRC were evaluated and compared.

RESULTS

Among 11,006 participants in this study, 57% were male, 76% were white, and 80% had stage 4 disease. Within the total cohort, 2379 had eoCRC and 8627 had aoCRC. Among patients with eoCRC, 4.2% had a tumor with high microsatellite instability and/or deficient mismatch repair (MSI-H/dMMR) and 6.8% with aoCRC had an MSI-H/dMMR tumor (p < 0.001). The most frequent somatic mutations involved TP53, APC, and KRAS, with the most significant difference in BRAF, which was more frequently mutated in aoCRC (9.8% vs. 4.7%, p < 0.0001). In total, 1413 (59.4%) eoCRC and 4898 (56.8%) aoCRC patients had matched normal specimen (blood or saliva) sequencing and a PGV was identified in 6.9% of eoCRC and 5.0% of aoCRC patients.

CONCLUSIONS

Somatic and germline mutation profiles were similar for eoCRC and aoCRC patients and may not adequately explain differences in tumor behavior and age of disease onset.

Feasibility of using patient navigation to improve identification of hereditary cancer syndromes in newly diagnosed patients with colorectal cancer

PURPOSE

Germline genetic testing to identify hereditary cancer syndromes in patients newly diagnosed with colorectal cancer (CRC) carries substantial benefits. We examined the feasibility of using patient navigation, an evidence-based approach to reduce structural barriers to recommended care, to improve test completion by increasing pretest counseling attendance.

METHODS

We conducted key informant interviews with representatives from organizations providing cancer care to CRC patients. Interviews included questions derived from the Consolidated Framework for Implementation Research, which delineates barriers and facilitators to implementing evidence-based practices. We used an inductive-deductive coding approach to identify themes related to program feasibility.

RESULTS

We interviewed 19 participants across 13 organizations. Key feasibility barriers included funding to implement and sustain a navigation program, staffing and supervising the navigator role, health information technology needs, gaining administrators' buy-in, and evolving genetic service delivery models. Participants suggested multiple strategies to address implementation barriers, but most would prefer other approaches to improve genetic test completion over implementing a genomics-focused patient navigation program.

CONCLUSION

Stakeholders across a range of health care organizations saw limited value in improving the identification of hereditary CRC syndromes by implementing a program designed to increase pretest genetic counseling attendance. The need to scale up genetic testing has shifted interest toward delivery models better integrated in established care pathways, requiring fewer resources and providing broader reach.

Universal screening for Lynch syndrome in endometrial cancer diagnoses in Auckland, New Zealand: The initial experience

BACKGROUND

Universal mismatch repair immunohistochemistry (MMR IHC) tumour testing in endometrial cancer (EC) for Lynch syndrome (LS) was introduced in Auckland, New Zealand, in January 2017. Identifying patients with LS allows them and their families to access risk reduction strategies. Universal MMR IHC testing aids in the molecular classification of EC and has prognostic and therapeutic implications.

AIM

We aimed to determine the incidence of LS in women with EC in Auckland, New Zealand, following the introduction of MMR testing and the impact of universal screening on local genetic services.

MATERIALS AND METHODS

This is a retrospective clinicopathological evaluation of women with a new EC diagnosis referred to the Auckland Gynaecological Oncology Unit from 1/1/17 to 31/12/18. Patient data were extracted from the Gynaecological Oncology Unit database and electronic records, and analysed using descriptive statistics.

RESULTS

During the study period, 409 patients were diagnosed with EC, with an over-representation of Pacific Islanders (32.5%). Of these, 82.6% underwent MMR IHC testing, 20% were MMR-deficient (MMRd), and 71% had somatic hypermethylation. The Pacific Islander population had a 64% (odds ratio 0.36, P = 0.005) reduction in the odds of having MMRd tumours compared with Europeans. Of the patients who underwent MMR IHC testing, 5.5% were referred to a genetic clinic for germline testing. LS was confirmed in eight patients (2.3%).

CONCLUSION

LS was diagnosed in 2.3% of patients. There was an over-representation of Pacific Islanders in the EC group but not among those diagnosed with LS.

Lynch syndrome screening in colorectal and endometrial cancers in Iceland

BACKGROUND AND PURPOSE

Screening for Lynch syndrome (LS) with mismatch repair (MMR) protein immunohistochemistry (IHC) in all patients with newly diagnosed colorectal (CRC) and endometrial cancer (EC) was implemented in Iceland in 2017. The aim of the study is to assess the accuracy of screening in 2020-2022 and compare it to 2017-2019 when screening was initiated.

PATIENTS/MATERIALS AND METHODS

All patients diagnosed with CRC and EC according to the Icelandic Cancer Registry in 2020-2022 were included. Screening results were crossmatched with a genotyping database from deCODE to calculate sensitivity and specificity for LS detection.   Results: In 2020-2022, 429 of 522 (82%) diagnosed CRCs were stained and 90 of 106 (85%) ECs, compared to 74% of CRCs and 82% of ECs in 2017-2019. The screening protocol was followed in 90% of cases for CRCs and 95% of cases for ECs compared to 89% and 68% during 2017-2019. The sensitivity of IHC as a screening method for LS was 70% and specificity 88% with a positive and negative predictive value of 8.4% and 99.4%, respectively.

INTERPRETATION

Three LS cases were missed with MMR IHC (1 MSH6 and 2 PMS2 carriers), it is possible these patients had sporadic cancers unrelated to their LS carrier status. MSH6 and PMS2 deficiency strongly predicts LS in Iceland.

Case report: Exploring Lynch Syndrome through genomic analysis in a mestizo Ecuadorian patient and his brother

Lynch Syndrome (LS) is a hereditary disorder characterized by genetic mutations in DNA mismatch repair genes, affecting approximately 0.35% of the population. LS primarily increases the risk of colorectal cancer (CRC), as well as various other cancer types like endometrial, breast, and gastric cancers. Microsatellite instability, caused by MMR gene mutations, is a key feature of LS, impacting genes such as MLH1, MSH2, MSH6, and PMS2. Pathology tests studying microsatellite instability and immunohistochemical staining are used to diagnose LS. Furthermore, next-generation sequencing (NGS) allows for a thorough investigation of cancer susceptibility genes. This approach is crucial for identifying affected individuals and managing their care effectively. This study evaluated two siblings who harbored a mutation in the MLH1 gene associated with LS. The older brother was diagnosed with CRC at 24, while the younger brother remains asymptomatic at 7 years old. Genetic testing confirmed the presence of the MLH1 mutation in both siblings. Ancestry analysis showed a mix of African, European, and Native American heritage, common among Ecuadorians. Both siblings shared a family history of cancer, suggesting hereditary factors. Treatment involved surgery and chemotherapy for the older brother, emphasizing the importance of genetic testing for siblings with a cancer family history. NGS plays a pivotal role in identifying genetic mutations and guiding treatment decisions, demonstrating its significance in managing LS and other hereditary cancers.

Localized Rectal Cancer: Indian Consensus and Guidelines

The rising incidence of colorectal cancer (CRC) in India, particularly the prevalence of rectal cancer over colon cancer (0.7:1), has been a growing concern in recent decades; especially notable is the trend of increasing cases among young CRC patients. Given the diverse treatment approaches for rectal cancer globally and the varying economic capacities of patients in low to middle-income countries (LMICs) like India, it is essential to establish consensus guidelines that are specifically tailored to meet the needs of these patients. To achieve this, a panel comprising 30 eminent rectal cancer experts convened to conduct a comprehensive and impartial evaluation of existing practices and recent advancements in the field. Through meticulous scrutiny of published literature and a consensus-building process that involved voting on pertinent questions, the panel formulated management strategies. These recommendations are the result of a rigorous, evidence-based process and encapsulate the collective wisdom and judgment of leading authorities in the field.

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.

Characteristics of Cancer in Subjects Carrying Lynch Syndrome-Associated Gene Variants in Taiwanese Population: A Hospital-Based Study in Taiwan

Lynch syndrome (LS) is an autosomal dominant disorder characterized by increased risks of colorectal and endometrial cancers. LS is defined by pathogenic variants in mismatch repair (MMR) genes, including MLH1, MSH2, and MSH6. Data on the prevalence and associated cancer risks of LS in the Han Chinese population remain limited. In this study, using a broad biobank approach through the Taiwan Precision Medicine Initiative (TPMI), we identified LS-associated MMR gene variants within a cohort of 42,828 participants from a Taiwanese medical center. A total of 89 individuals were found to carry pathogenic MMR variants: MLH1 (n = 22, 25%), MSH2 (n = 47, 53%), and MSH6 (n = 20, 22%). The overall prevalence of MMR variants was calculated, and cancer incidence rates among carriers were determined. The prevalence of MMR variants in the study population was 1 in 481. The distribution of MLH1, MSH2, and MSH6 variants were 24.7%, 52.8%, and 22.5%, respectively. Cumulative cancer incidence rates of carriers were 40.9% for MLH1 carriers, 29.8% for MSH2, and 40% for MSH6. Among the 19 individuals who underwent colonoscopy screening, the prevalence of polyps was similar to that of the control group (adenoma detection rate: 32% vs 26%, p = 0.585). A meticulous analysis of the detected polyps in seven participants, considering factors such as location, size, morphology, and pathological features, showed no significant differences from controls. A significant cancer risk is associated with LS-related MMR variants in the Taiwanese population. The apparent under diagnosis of LS highlights the urgent need for enhanced surveillance and genetic counseling in this demographic. Our findings suggest that adjustments in the current screening protocols may be warranted to better identify and manage at-risk individuals.

Two Decades of Progress in Personalized Medicine of Colorectal Cancer in Serbia-Insights from the Institute for Oncology and Radiology of Serbia

BACKGROUND

It is projected that, by 2040, the number of new cases of colorectal cancer (CRC) will increase to 3.2 million, and the number of deaths to 1.6 million, highlighting the need for prevention strategies, early detection and adequate follow-up. In this study, we aimed to provide an overview of the progress in personalized medicine of CRC in Serbia, with results and insights from the Institute for Oncology and Radiology of Serbia (IORS), and to propose guidance for tackling observed challenges in the future.

METHODS

Epidemiological data were derived from official global and national cancer registries and IORS electronic medical records. Germline genetic testing for Lynch syndrome was performed by Next Generation Sequencing. RAS and BRAF mutation analyses were performed using qPCR diagnostic kits.

RESULTS

Epidemiology and risk factors, prevention and early detection programs, as well as treatment options and scientific advances have been described in detail. Out of 103 patients who underwent germline testing for Lynch syndrome, 19 (18.4%) showed a mutation in MMR genes with pathogenic or likely pathogenic significance and 8 (7.8%) in other CRC-associated genes (APC, CHEK2, MUTYH). Of 6369 tested patients, 50.43% had a mutation in KRAS or NRAS genes, while 9.54% had the V600 mutation in the BRAF gene.

CONCLUSIONS

Although significant improvements in CRC management have occurred globally in recent years, a strategic approach leading to population-based systemic solutions is required. The high incidence of young-onset CRC and the growing elderly population due to a rise in life expectancy will be especially important factors for countries with limited healthcare resources like Serbia.

Universal screening of colorectal tumors for lynch syndrome: a survey of patient experiences and opinions

BACKGROUND

Lynch syndrome represents the most common hereditary cause of both colorectal and endometrial cancer. It is caused by defects in mismatch repair genes, as well as EPCAM. Universal screening of colon tumors for Lynch syndrome via microsatellite instability (MSI) and/or immunohistochemistry (IHC) can identify patients and families at risk to develop further cancers and potentially impact surveillance and treatment options. The approach to implementation of universal screening, taking ethical considerations into account, is critical to its effectiveness, with patient perspectives providing valuable insight.

METHODS

Patients whose colon tumors underwent universal screening at Penn State Hershey Medical Center over a period of 2.5 years were mailed a survey on universal screening in 2017. Along with the survey, they received a recruitment letter and a summary explanation of research. The survey included both multiple choice and free-response questions that covered topics including respondent knowledge of Lynch syndrome, attitudes toward universal screening and experiences with the screening protocol as implemented.

RESULTS

Sixty-six of 297 possible patients (22.2%) responded to the survey, including 13 whose screening results raised concern for Lynch syndrome. 75.8% of respondents supported universal tumor screening without informed consent. 92.4% preferred receiving screening results regardless of outcome. Respondents described benefits to screening for themselves and their families.

CONCLUSIONS

While broadly supporting universal tumor screening without informed consent, respondents also wanted more information shared about the screening policy, as well as their results. These patient preferences should be one of many factors considered when implementing universal screening and can also inform practices regarding both tumor profiling and universal genetic testing, which is becoming more prevalent.

Gastrointestinal Cancer Precursor Conditions and Their Detection

Gastrointestinal cancers are a leading cause of cancer morbidity and mortality. Many gastrointestinal cancers develop from cancer precursor lesions, which are commonly found in individuals with hereditary cancer syndromes. Hereditary cancer syndromes have advanced our understanding of cancer development and progression and have facilitated the evaluation of cancer prevention and interception efforts. Common gastrointestinal hereditary cancer syndromes, including their organ-specific cancer risk and surveillance recommendations, are reviewed in this article. The management of common gastroesophageal, pancreatic, and colonic precursor lesions is also discussed, regardless of their genetic background. Further research is needed to advance chemoprevention and immunoprevention strategies.

Universal Lynch Syndrome Screening in Colorectal Cancer: A 5-Year Experience of a Portuguese Pathology Department

Lynch syndrome (LS) is a prevalent genetic condition associated with colorectal cancer (CRC). Accurate identification of LS patients is challenging, and a universal tumor screening approach has been recommended. We present the methodology and results of universal LS screening in our hospital's Pathology Department. This retrospective study analyzed CRC tumors from a 5-year period (2017-2021). Immunohistochemistry was used to assess MMR protein expression, followed by BRAF V600E analysis and MLH1 promoter methylation. Statistical analysis examined associations between clinicopathologic variables MMR status and LS-suspected tumors. The study analyzed 939 colorectal carcinomas, with 8.7% exhibiting mismatch repair (MMR) deficiency, significantly lower than previous research. After applying the algorithm, 24 LS-suspected cases were identified, accounting for 2.6% of tested patients and 29.3% of MMR-deficient tumors. Our study establishes the feasibility of universal testing for all new cases of CRC in detecting individuals at risk for LS, even in the absence of clinical information. To gain a comprehensive understanding of the MMR status in our population, further investigations are warranted.

Disparities in race, ethnicity, sex, and age inclusion in pancreatic cancer screening studies: a systematic review and meta-analysis

BACKGROUND AND AIMS

Substantial differences exist in pancreatic cancer outcomes across ethnoracial stratifications. We sought to assess racial, ethnic, sex, and age reporting and inclusion of participants in pancreatic cancer screening studies.

METHODS

A systematic search of Cochrane Library, Ovid Embase, Google Scholar, Ovid MEDLINE, PubMed, Scopus, and Web of Science Core Collection from inception to 2022 was conducted. Original studies on pancreatic cancer screening were identified and assessed for reporting and inclusion on race, ethnicity, sex, and age. The pooled proportions of study participants for these characteristics were calculated and compared with population-based benchmarks.

RESULTS

Among 27 eligible pancreatic cancer screening studies, 26 reported data on either sex, race, or ethnicity, with a total of 5273 participants. Information on participant sex was reported by 26, race by 12, and ethnicity by 8 studies. Participants in these studies were almost all white (pooled proportion, 93.1%; 95% confidence interval [CI], 89.7-96.4) and non-Latino (pooled proportion, 97.4%; 95% CI, 94.0-100), and these groups were over-represented when compared with the general population. Female participants were well represented, with a pooled proportion of 63.2% (95% CI, 59.9-66.6). When reported, mean or median participant age was <60 years. Meta-regression revealed higher proportions of female participants in studies from the United States (P = .002). No association between increasing participation of racial or ethnic under-represented populations and study quality, ascending year of publication, or source of study funding was noted.

CONCLUSIONS

Substantial disparities in race, ethnicity, sex, and age reporting and inclusion in pancreatic cancer studies were noted, even among high-quality and publicly funded studies.

State of the art: Targeting microsatellite instability in gastrointestinal cancers

DNA mismatch repair (MMR) deficiency and the associated microsatellite instability (MSI) phenotype has become a subject of enormous interest in recent years due to the demonstrated efficacy of immune checkpoint inhibitors (ICI) in advanced tumours. Assessing MSI in patients with gastrointestinal tract (GI) cancers is useful to exclude Lynch syndrome, but also to predict benefit for ICI. Following review of the relevant literature, this review article aims to outline the clinicopathologic spectrum of MSI and mismatch repair deficiency (dMMR) in the GI tract, hepatobiliary system and pancreas and discuss the therapeutic consideration in this disease.

Detection of (pre)cancerous colorectal lesions in Lynch syndrome patients by microsatellite instability liquid biopsy

Lynch syndrome (LS) is an inherited condition characterized by an increased risk of developing cancer, in particular colorectal cancer (CRC). Microsatellite instability (MSI) is the main feature of (pre)cancerous lesions occurring in LS patients. Close endoscopic surveillance is the only option available to reduce CRC morbidity and mortality. However, it may fail to intercept interval cancers and patients' compliance to such an invasive procedure may decrease over the years. The development of a minimally invasive test able to detect (pre)cancerous colorectal lesions, could thus help tailor surveillance programs in LS patients. Taking advantage of an endoscopic surveillance program, we retrospectively assessed the instability of five microsatellites (BAT26, BAT25, NR24, NR21, and Mono27) in liquid biopsies collected at baseline and possibly at two further endoscopic rounds. For this purpose, we tested a new multiplex drop-off digital polymerase chain reaction (dPCR) assay, reaching mutant allele frequencies (MAFs) as low as 0.01%. Overall, 78 plasma samples at the three time-points from 18 patients with baseline (pre)cancerous lesions and 18 controls were available for molecular analysis. At baseline, the MAFs of BAT26, BAT25 and NR24 were significantly higher in samples of patients with lesions but did not differ with respect to the grade of dysplasia or any other clinico-pathological characteristics. When all markers were combined to determine MSI in blood, this test was able to discriminate lesion-bearing patients with an AUC of 0.80 (95%CI: 0.66; 0.94).

Microsatellite Instability Testing and Prognostic Implications in Colorectal Cancer

Given the crucial predictive implications of microsatellite instability (MSI) in colorectal cancer (CRC), MSI screening is commonly performed in those with and at risk for CRC. Here, we compared results from immunohistochemistry (IHC) and the droplet digital PCR (ddPCR) MSI assay on formalin-fixed paraffin-embedded tumor samples from 48 patients who underwent surgery for colon and rectal cancer by calculating Cohen's kappa measurement (k), revealing high agreement between the methods (k = 0.915). We performed Kaplan-Meier survival analyses and univariate and multivariate Cox regression to assess the prognostic significance of ddPCR-based MSI and to identify clinicopathological features associated with CRC outcome. Patients with MSI-high had better overall survival (OS; p = 0.038) and disease-free survival (DFS; p = 0.049) than those with microsatellite stability (MSS). When stratified by primary tumor location, right-sided CRC patients with MSI-high showed improved DFS, relative to those with MSS (p < 0.001), but left-sided CRC patients did not. In multivariate analyses, MSI-high was associated with improved OS (hazard ratio (HR) = 0.221, 95% confidence interval (CI): 0.026-0.870, p = 0.042), whereas the loss of DNA mismatch repair protein MutL homolog 1 (MLH1) expression was associated with worse OS (HR = 0.133, 95% CI: 0.001-1.152, p = 0.049). Our results suggest ddPCR is a promising tool for MSI detection. Given the opposing effects of MSI-high and MLH1 loss on OS, both ddPCR and IHC may be complementary for the prognostic assessment of CRC.

Province-Wide Ascertainment of Lynch Syndrome in Manitoba

BACKGROUND & AIMS

We describe the experience of Lynch syndrome (LS) diagnosis in the province of Manitoba, Canada, over the past 20 years.

METHODS

We performed a retrospective review of charts from the provincial Genetics Clinic from January 1, 2000, to May 31, 2023. We extracted data on individuals identified to carry a germline pathogenic or likely pathogenic LS gene variant, the mode of ascertainment, family history, and cascade genetic testing (CGT). Data were stratified and compared before and after the year of implementation (October 2013) of the provincial LS screening program (LSSP) and ascertainment by the LSSP vs clinic referrals (CRs).

RESULTS

Between 2014 and 2021, 50 of 101 (49.5%) index cases were identified by the LSSP compared with 51 of 101 (50.5%) from CRs. The proportion of PMS2 variants was 34% (17 of 50) for LSSP index cases compared with 21.6% (11 of 51) for CRs from 2014 to 2021 (P < .001). Among CRs from 2014 to 2021, 24 of 51 (47.1%) families met the Amsterdam criteria, compared with 11 of 50 (22.0%) for the LSSP (P = .01). CGT occurred among 46.8% (95 of 203; average, 1.9 relatives/index) of first-degree relatives of CR index cases vs 36.5% (84 of 230; average, 1.7 relatives/index) of first-degree relatives of LSSP index cases (P = .03). Daughters were most likely to undergo CGT.

CONCLUSIONS

A tumor screening program is more effective at detecting individuals with lower penetrant gene variants and families who do not meet traditional family history-based criteria. Cascade genetic testing is higher among clinic referrals compared with the screening program. These findings suggest a complementary role of these 2 ascertainment methods for Lynch syndrome.

Hereditary cancer testing in a diverse sample across three breast imaging centers

PURPOSE

Up to 10% of all breast cancers (BC) are attributed to inherited pathogenic variants (PV) in BC susceptibility genes; however, most carriers of PVs remain unidentified. Here, we sought to determine the yield of hereditary cancer gene PVs among diverse women attending breast imaging centers, who could benefit from enhanced surveillance and/or risk reduction interventions.

METHODS

This cross-sectional retrospective cohort study included consecutive women, unselected for personal or family cancer history, who were offered genetic testing for hereditary cancer genes at the time of breast imaging at three centers (November 2020-March 2022).

RESULTS

Among 1943 patients (median age: 66 years), self-reported race/ethnicity was White (34.5%), Hispanic (27.7%), African American (17.9%), Asian (4.5%), Ashkenazi Jewish (0.6%), Other (3.5%), and missing (13.0%). Thirty-nine patients (2%) were identified as carriers of a PV in an autosomal dominant clinically actionable hereditary breast and ovarian cancer (HBOC)-related or Lynch syndrome gene, most frequently, BRCA2 (6/39; 15.4%), PALB2 (8/39; 20.5%), CHEK2 (10/39; 25.6%), and PMS2 (5/39; 12.8%). Of the 34 PVs with known race/ethnicity, 47% were detected among non-White patients. Overall, 354/1,943 (18.2%) of patients met NCCN guidelines for HBOC gene testing and only 15/39 (38.5%) patients with an autosomal dominant clinically actionable PV met guidelines.

CONCLUSION

This population health approach extended the reach of genetic cancer risk assessment in a diverse population and highlighted the limits of a guideline-based approach. This may help address inequity in access to risk-appropriate screening and cancer prevention.

Mismatch repair deficiency and microsatellite instability in urothelial carcinoma: a systematic review and meta-analysis

Background

Mismatch repair deficiency (dMMR) and microsatellite instability-high (MSI-H) occur in a subset of cancers and have been shown to confer sensitivity to immune checkpoint inhibition (ICI); however, there is a lack of prospective data in urothelial carcinoma (UC).

Methods and analysis

We performed a systematic review to estimate the prevalence of dMMR and MSI-H in UC, including survival and clinical outcomes. We searched for studies published up to 26 October 2022 in major scientific databases. We screened 1745 studies and included 110. Meta-analyses were performed if the extracted data were suitable.

Results

The pooled weighted prevalences of dMMR in bladder cancer (BC) and upper tract UC (UTUC) were 2.30% (95% CI 1.12% to 4.65%) and 8.95% (95% CI 6.81% to 11.67%), respectively. The pooled weighted prevalences of MSI-H in BC and UTUC were 2.11% (95% CI 0.82% to 5.31%) and 8.36% (95% CI 5.50% to 12.53%), respectively. Comparing localised versus metastatic disease, the pooled weighted prevalences for MSI-H in BC were 5.26% (95% CI 0.86% to 26.12%) and 0.86% (95% CI 0.59% to 1.25%), respectively; and in UTUC, they were 18.04% (95% CI 13.36% to 23.91%) and 4.96% (95% CI 2.72% to 8.86%), respectively. Cumulatively, the response rate in dMMR/MSI-H metastatic UC treated with an ICI was 22/34 (64.7%) compared with 1/9 (11.1%) with chemotherapy.

Conclusion

Both dMMR and MSI-H occur more frequently in UTUC than in BC. In UC, MSI-H occurs more frequently in localised disease than in metastatic disease. These biomarkers may predict sensitivity to ICI in metastatic UC and resistance to cisplatin-based chemotherapy.

Tumor Testing and Genetic Analysis to Identify Lynch Syndrome Patients in an Italian Colorectal Cancer Cohort

Lynch syndrome (LS) is an inherited cancer susceptibility syndrome caused by germline mutations in a DNA mismatch repair (MMR) gene or in the EPCAM gene. LS is associated with an increased lifetime risk of colorectal cancer (CRC) and other malignancies. The screening algorithm for LS patient selection is based on the identification of CRC specimens that have MMR loss/high microsatellite instability (MSI-H) and are wild-type for BRAFV600. Here, we sought to clinically and molecularly characterize patients with these features. From 2017 to 2023, 841 CRC patients were evaluated for MSI and BRAFV600E mutation status, 100 of which showed MSI-H. Of these, 70 were wild-type for BRAFV600. Among these 70 patients, 30 were genetically tested for germline variants in hereditary cancer predisposition syndrome genes. This analysis showed that 19 of these 30 patients (63.3%) harbored a germline pathogenic or likely pathogenic variant in MMR genes, 2 (6.7%) harbored a variant of unknown significance (VUS) in MMR genes, 3 (10%) harbored a VUS in other cancer-related genes, and 6 (20%) were negative to genetic testing. These findings highlight the importance of personalized medicine for tailored genetic counseling, management, and surveillance of families with LS and other hereditary cancer syndromes.

Advances in vaccine development for cancer prevention and treatment in Lynch Syndrome

Lynch Syndrome (LS) is one of the most common hereditary cancer syndromes, and is caused by mutations in one of the four DNA mismatch repair (MMR) genes, namely MLH1, MSH2, MSH6 and PMS2. Tumors developed by LS carriers display high levels of microsatellite instability, which leads to the accumulation of large numbers of mutations, among which frameshift insertion/deletions (indels) within microsatellite (MS) loci are the most common. As a result, MMR-deficient (MMRd) cells generate increased rates of tumor-specific neoantigens (neoAgs) that can be recognized by the immune system to activate cancer cell killing. In this context, LS is an ideal disease to leverage immune-interception strategies. Therefore, the identification of these neoAgs is an ongoing effort for the development of LS cancer preventive vaccines. In this review, we summarize the computational methods used for in silico neoAg prediction, including their challenges, and the experimental techniques used for in vitro validation of their immunogenicity. In addition, we outline results from past and on-going vaccine clinical trials and highlight avenues for improvement and future directions.

PREMM5 distinguishes sporadic from Lynch syndrome-associated MMR-deficient/MSI-high colorectal cancer

Current algorithms for diagnosing Lynch syndrome (LS) include multistep molecular tumor tests to distinguish LS-associated from sporadic colorectal cancer (CRC), which add cost and complexity to the evaluation. We hypothesized that PREMM5, a clinical LS prediction tool, could be an alternative approach to screen for LS, thereby lessening the need for specialized molecular diagnostics. We reviewed a consecutively ascertained institutional cohort of 1058 CRC patients on whom pathologic and clinical data were available, including prior LS germline testing. Data from MMR-D/MSI-H CRC patients were reviewed and PREMM5 scores were calculated for each individual. Using a PREMM5 score cutoff ≥ 2.5% to characterize the need for germline testing, we determined the rate of pathogenic/likely pathogenic germline variants (PGVs) in LS genes in patients with PREMM5 scores ≥ 2.5% versus < 2.5%. Sensitivity and negative predictive values (NPV) of PREMM5 were calculated for all MMR-D/MSI-H CRC patients, and those with MLH1-deficient CRC. MMR IHC and/or MSI results were available on 572/1058 cases. We identified 74/572 (12.9%) cases as MMR-D/MSI-H, of which 28/74 (37.8%) harbored a LS PGV. 11/49 (22.4%) patients with MLH1-deficient CRC harbored a LS PGV. PREMM5 had 100% sensitivity (95% CI: 87.7-100 for any MMR-D/MSI-H; 95% CI: 71.5-100 for MLH1-deficient CRC) and 100% NPV (95% CI: 83.2-100 for any MMR-D/MSI-H; 95% CI: 82.4-100 for MLH1-deficient CRC) for identifying LS PGVs in these cohorts. PREMM5 accurately distinguishes LS- from non-LS-associated MMR-D/MSI-H CRC without additional somatic molecular testing. These findings are particularly relevant for limited-resource settings where advanced molecular diagnostics may be unavailable.

Severe Immune-Mediated Colitis Induced by Checkpoint Inhibitors in an Adolescent With Lynch Syndrome

Lynch syndrome is a hereditary colorectal cancer caused by mutations in DNA mismatch repair genes. Immune checkpoint therapies have shown promise in treating Lynch syndrome-associated cancers but can lead to immune-related adverse events, such as colitis. In this report, we present a severe case of immune-mediated colitis (IMC) induced by checkpoint inhibitors in a young patient with Lynch syndrome. This 20-year-old male with Lynch syndrome and a history of glioblastoma underwent dual checkpoint therapy, after initial treatment with systemic steroids. Despite this, his condition worsened, resulting in complications, such as toxic megacolon and small bowel obstruction. He was subjected to various treatments, including infliximab and vedolizumab, but ultimately required total abdominal colectomy with J-pouch creation. This case highlights the challenges of managing severe IMC in patients with Lynch syndrome. The patient's suboptimal response to standard treatments and the development of complications emphasizes the need for a better understanding and alternative therapeutic options for IMC. This case also calls into question whether a subset of patients with IMC should be "treated to target," even though the current standard of care for IMC is guided by symptom response, and if so, further research is necessary to identify potential therapeutic targets. Further research is also required to understand the mechanisms of IMC and develop effective treatment strategies tailored to patients with Lynch syndrome and immune-related adverse events.

The Prevalence and Molecular Landscape of Lynch Syndrome in the Affected and General Population

BACKGROUND

Lynch syndrome (LS) is the most frequent genetically pre-disposed colorectal cancer (CRC) syndrome, accounting for 2-3% of all CRC cases. In Estonia, ~1000 new cases are diagnosed each year. This retroactive and prospective study aimed to estimate the prevalence of LS and describe disease-causing variants in mismatch repair (MMR) genes in a diagnostic setting and in the Estonian general population.

METHODS

LS data for the diagnostic cohort were gathered from 2012 to 2022 and data for the general population were acquired from the Estonian Biobank (EstBB). Furthermore, we conducted a pilot study to estimate the improvement of LS diagnostic yield by raising the age limit to >50 years for immunohistochemistry analysis of MMR genes.

RESULTS

We estimated LS live birth prevalence between 1930 and 2003 in Estonia at 1:8638 (95% CI: 1: 9859-7588). During the study period, we gathered 181 LS individuals. We saw almost a six-fold increase in case prevalence, probably deriving from better health awareness, improved diagnostic possibilities and the implementation of MMR IHC testing in a broader age group.

CONCLUSION

The most common genes affected in the diagnostic and EstBB cohorts were MLH1 and PMS2 genes, respectively. The LS diagnosis mean age was 44.8 years for index cases and 36.8 years (p = 0.003) for family members. In the MMR IHC pilot study, 29% had LS.

Dietary fibre and health: the story so far

The present paper reviews progress in research on dietary fibre and human health over the past five decades. There is now convincing evidence from prospective cohort studies that diets low in dietary fibre are associated with increased risk of common non-communicable diseases including CVD, type 2 diabetes and colorectal cancer. These findings provide strong support for hypotheses proposed by Denis Burkitt 50 years ago, based on very limited evidence but with considerable imagination and insight. For the first two to three decades of this period, research on dietary fibre was hampered by the lack of consensus about the definition, and measurement, of this complex and diverse dietary component and by the lack of appropriate tools for investigating the gut microbiome that is central to understanding mechanisms of action. Recent technical and scientific advances in microbiome research (based on fast, low-cost, DNA sequencing) are facilitating investigation of the associations between dietary fibre, the gut microbiome and human health. Current challenges include the need for agreement about the characteristics of a healthy gut microbiome. Although the health benefits attributed to higher dietary fibre intake are likely to be shared with most types of dietary fibre, one should anticipate that different sources of dietary fibre and the other components (resistant starch and non-digestible oligosaccharides) that make up dietary fibre will have characteristically different effects on human physiology and disease risk. In conclusion, population-level intakes of dietary fibre are low and there is a public health priority to develop and implement more effective interventions to increase intake.

Patterns of DNA mismatch repair protein expression for primary and recurrent colorectal cancer at an advanced surgical unit: A retrospective audit

AIM

Lynch syndrome is an inherited cancer syndrome associated with an increased lifetime risk of colorectal cancer (CRC) and characterized by germline mutations to one of four DNA mismatch repair (MMR) genes. Immunohistochemical (IHC) testing is used to screen for Lynch syndrome; however, despite routine completion following resection of primary CRC, it is only variably completed following resection of recurrent disease. This may be significant, as MMR protein expression can change from primary to recurrent CRC. The primary aim of this study is to investigate how MMR profiles change from primary to recurrent CRC; the secondary aim is to assess rates of MMR testing of primary and recurrent disease.

METHOD

We conducted a retrospective analysis of patients undergoing surgery for recurrent CRC from 2018-19 at a high-volume institution. MMR profiles were obtained following both primary and recurrent resection of CRC, and MMR protein expression was evaluated from both time points.

RESULTS

A total of 107 patients met the inclusion criteria and IHC results were obtained for both primary and recurrent resections in 85 cases. MMR profiles changed in nine patients (10.6%), with a loss of staining from primary to recurrent disease in six (7.1%) and a gain of staining in three (3.5%). IHC testing was completed following 88.7% of primary and 39.3% of recurrent resections.

CONCLUSION

MMR profiles can change from primary to recurrent CRC and repeat MMR testing for recurrent CRC is completed in only a minority of cases.

Microsatellite Instability and Aberrant Pre-mRNA Splicing: How Intimate Is It?

Cancers that belong to the microsatellite instability (MSI) class can account for up to 15% of all cancers of the digestive tract. These cancers are characterized by inactivation, through the mutation or epigenetic silencing of one or several genes from the DNA MisMatch Repair (MMR) machinery, including MLH1, MLH3, MSH2, MSH3, MSH6, PMS1, PMS2 and Exo1. The unrepaired DNA replication errors turn into mutations at several thousand sites that contain repetitive sequences, mainly mono- or dinucleotides, and some of them are related to Lynch syndrome, a predisposition condition linked to a germline mutation in one of these genes. In addition, some mutations shortening the microsatellite (MS) stretch could occur in the 3'-intronic regions, i.e., in the ATM (ATM serine/threonine kinase), MRE11 (MRE11 homolog) or the HSP110 (Heat shock protein family H) genes. In these three cases, aberrant pre-mRNA splicing was observed, and it was characterized by the occurrence of selective exon skipping in mature mRNAs. Because both the ATM and MRE11 genes, which as act as players in the MNR (MRE11/NBS1 (Nibrin)/RAD50 (RAD50 double strand break repair protein) DNA damage repair system, participate in double strand breaks (DSB) repair, their frequent splicing alterations in MSI cancers lead to impaired activity. This reveals the existence of a functional link between the MMR/DSB repair systems and the pre-mRNA splicing machinery, the diverted function of which is the consequence of mutations in the MS sequences.

Young Patients With Colorectal Cancer Have Higher Early Mortality but Better Long-Term Survival

INTRODUCTION

To define the prognosis of colorectal cancer (CRC) in young patients and to compare their postoperative treatment with that of older patients.

METHODS

This multicenter study enrolled 5,457 patients with primary CRC who underwent surgical resection. The overall survival (OS), clinicopathologic characteristics, and postoperative treatment of 253 young patients aged 18-44 years and 5,204 older patients aged 44-80 years were analyzed.

RESULTS

The OS rate was 77.1% for young and 74.2% for older patients (P = 0.348). Landmark analysis showed a significant difference in survival between young and older patients, with 63.8% of deaths among young patients being within 25 months of surgery compared with 42.4% among older patients (P = 0.002). Among those who survived more than 25 months, young patients had significantly better survival than older patients (P = 0.009). Multivariable analysis of young patients revealed that the tumor location, perineural invasion, and stage were associated with poor survival within 25 months; after this period, stage was the only prognostic marker. Young patients were more likely to receive chemotherapy, particularly multiagent regimens. For young patients, no significant difference in OS was found based on the chemotherapy regimen, regardless of disease stage (II, III, or IV, all P > 0.05). In addition, unlike in older patients, no difference in OS was found in young patients regardless of the drug regimen administered (all P > 0.05).

DISCUSSION

Young-onset CRC may have a unique disease biology that warrants further research and therapy development.

Relatives from Hereditary Breast and Ovarian Cancer and Lynch Syndrome Families Forgoing Genetic Testing: Findings from the Swiss CASCADE Cohort

Cascade genetic testing of relatives from families with pathogenic variants associated with hereditary breast and ovarian cancer (HBOC) or Lynch syndrome (LS) has important implications for cancer prevention. We compared the characteristics of relatives from HBOC or LS families who did not have genetic testing (GT (−) group) with those who had genetic testing (GT (+) group), regardless of the outcome. Self-administered surveys collected cross-sectional data between September 2017 and December 2021 from relatives participating in the CASCADE cohort. We used multivariable logistic regression with LASSO variable selection. Among n = 115 relatives who completed the baseline survey, 38% (n = 44) were in the GT (−) group. Being male (OR: 2.79, 95% CI: 1.10–7.10) and without a previous cancer diagnosis (OR: 4.47, 95% CI: 1.03–19.42) increased the odds of being untested by almost three times. Individuals from families with fewer tested relatives had 29% higher odds of being untested (OR: 0.71, 95% CI: 0.55–0.92). Reasons for forgoing cascade testing were: lack of provider recommendation, lack of time and interest in testing, being afraid of discrimination, and high out-of-pocket costs. Multilevel interventions designed to increase awareness about clinical implications of HBOC and LS in males, referrals from non-specialists, and support for testing multiple family members could improve the uptake of cascade testing.