Guidelines for the management of hereditary colorectal cancer from the British Society of Gastroenterology (BSG)/Association of Coloproctology of Great Britain and Ireland (ACPGBI)/United Kingdom Cancer Genetics Group (UKCGG)

Current management of familial adenomatous polyposis

INTRODUCTION

APC-associated polyposis is a rare hereditary disorder characterized by the development of multiple adenomas in the digestive tract. Individuals with APC-associated polyposis need to be managed by specialized multidisciplinary teams in dedicated centers.

AREAS COVERED

The study aimed to review the literature on Familial adenomatous polyposis (FAP) to provide an update on diagnostic and surgical management while focusing on strategies to minimize the risk of desmoid-type fibromatosis, cancer in anorectal remnant, and postoperative complications. FAP individuals require a comprehensive approach that includes diagnosis, surveillance, preventive surgery, and addressing specific extracolonic concerns such as duodenal and desmoid tumors. Management should be personalized considering all factors: genotype, phenotype, and personal needs. Total colectomy and ileo-rectal anastomosis have been shown to yield superior QoL results when compared to Restorative Procto colectomy and ileopouch-anal anastomosis with acceptable oncological risk of developing cancer in the rectal stump if patients rigorously adhere to lifelong endoscopic surveillance. Additionally, a low-inflammatory diet may prevent adenomas and cancer by modulating systemic and tissue inflammatory indices.

EXPERT OPINION

FAP management requires a multidisciplinary and personalized approach. Integrating genetic advances, innovative surveillance techniques, and emerging therapeutic modalities will contribute to improving outcomes and quality of life for FAP individuals.

Constitutional mismatch repair deficiency mimicking Lynch syndrome is associated with hypomorphic mismatch repair gene variants

Lynch syndrome (LS) and constitutional mismatch repair deficiency (CMMRD) are distinct cancer syndromes caused, respectively, by mono- and bi-allelic germline mismatch repair (MMR) variants. LS predisposes to mainly gastrointestinal and genitourinary cancers in adulthood. CMMRD predisposes to brain, haematological, and LS-spectrum cancers from childhood. Two suspected LS patients with first cancer diagnosis aged 27 or 38 years were found to be homozygous for an MMR (likely) pathogenic variant, MSH6 c.3226C>T (p.(Arg1076Cys)), or variant of uncertain significance (VUS), MLH1 c.306G>A (p.(Glu102=)). MLH1 c.306G>A was shown to cause leaky exon 3 skipping. The apparent genotype-phenotype conflict was resolved by detection of constitutional microsatellite instability in both patients, a hallmark feature of CMMRD. A hypomorphic effect of these and other variants found in additional late onset CMMRD cases, identified by literature review, likely explains a LS-like phenotype. CMMRD testing in carriers of compound heterozygous or homozygous MMR VUS may find similar cases and novel hypomorphic variants. Individualised management of mono- and bi-allelic carriers of hypomorphic MMR variants is needed until we better characterise the associated phenotypes.

Systematic large-scale application of ClinGen InSiGHT APC -specific ACMG/AMP variant classification criteria substantially alleviates the burden of variants of uncertain significance in ClinVar and LOVD databases

Background

Pathogenic constitutional APC variants underlie familial adenomatous polyposis, the most common hereditary gastrointestinal polyposis syndrome. To improve variant classification and resolve the interpretative challenges of variants of uncertain significance (VUS), APC-specific ACMG/AMP variant classification criteria were developed by the ClinGen-InSiGHT Hereditary Colorectal Cancer/Polyposis Variant Curation Expert Panel (VCEP).

Methods

A streamlined algorithm using the APC -specific criteria was developed and applied to assess all APC variants in ClinVar and the InSiGHT international reference APC LOVD variant database.

Results

A total of 10,228 unique APC variants were analysed. Among the ClinVar and LOVD variants with an initial classification of (Likely) Benign or (Likely) Pathogenic, 94% and 96% remained in their original categories, respectively. In contrast, 41% ClinVar and 61% LOVD VUS were reclassified into clinically actionable classes, the vast majority as (Likely) Benign. The total number of VUS was reduced by 37%. In 21 out of 36 (58%) promising APC variants that remained VUS despite evidence for pathogenicity, a data mining-driven work-up allowed their reclassification as (Likely) Pathogenic.

Conclusions

The application of APC -specific criteria substantially reduced the number of VUS in ClinVar and LOVD. The study also demonstrated the feasibility of a systematic approach to variant classification in large datasets, which might serve as a generalisable model for other gene-/disease-specific variant interpretation initiatives. It also allowed for the prioritization of VUS that will benefit from in-depth evidence collection. This subset of APC variants was approved by the VCEP and made publicly available through ClinVar and LOVD for widespread clinical use.

Updated European guidelines for clinical management of familial adenomatous polyposis (FAP), MUTYH-associated polyposis (MAP), gastric adenocarcinoma, proximal polyposis of the stomach (GAPPS) and other rare adenomatous polyposis syndromes: a joint EHTG-ESCP revision

BACKGROUND

Hereditary adenomatous polyposis syndromes, including familial adenomatous polyposis and other rare adenomatous polyposis syndromes, increase the lifetime risk of colorectal and other cancers.

METHODS

A team of 38 experts convened to update the 2008 European recommendations for the clinical management of patients with adenomatous polyposis syndromes. Additionally, other rare monogenic adenomatous polyposis syndromes were reviewed and added. Eighty-nine clinically relevant questions were answered after a systematic review of the existing literature with grading of the evidence according to Grading of Recommendations, Assessment, Development, and Evaluation methodology. Two levels of consensus were identified: consensus threshold (≥67% of voting guideline committee members voting either 'Strongly agree' or 'Agree' during the Delphi rounds) and high threshold (consensus ≥ 80%).

RESULTS

One hundred and forty statements reached a high level of consensus concerning the management of hereditary adenomatous polyposis syndromes.

CONCLUSION

These updated guidelines provide current, comprehensive, and evidence-based practical recommendations for the management of surveillance and treatment of familial adenomatous polyposis patients, encompassing additionally MUTYH-associated polyposis, gastric adenocarcinoma and proximal polyposis of the stomach and other recently identified polyposis syndromes based on pathogenic variants in other genes than APC or MUTYH. Due to the rarity of these diseases, patients should be managed at specialized centres.

Non-metastatic colon cancer: French Intergroup Clinical Practice Guidelines for diagnosis, treatments, and follow-up (TNCD, SNFGE, FFCD, GERCOR, UNICANCER, SFCD, SFED, SFRO, ACHBT, SFP, AFEF, and SFR)

INTRODUCTION

This article is a summary of the French intergroup guidelines regarding the management of non-metastatic colon cancer (CC), revised in November 2022.

METHODS

These guidelines represent collaborative work of all French medical and surgical societies involved in the management of CC. Recommendations were graded in three categories (A, B, and C) according to the level of evidence found in the literature published up to November 2022.

RESULTS

Initial evaluation of CC is based on clinical examination, colonoscopy, chest-abdomen-pelvis computed tomography (CT) scan, and carcinoembryonic antigen (CEA) assay. CC is usually managed by surgery and adjuvant treatment depending on the pathological findings. The use of adjuvant therapy remains a challenging question in stage II disease. For high-risk stage II CC, adjuvant chemotherapy must be discussed and fluoropyrimidine monotherapy or oxaliplatin-based chemotherapy proposed according to the type and number of poor prognostic features. Oxaliplatin-based chemotherapy (FOLFOX or CAPOX) is the current standard for adjuvant therapy of patients with stage III CC. However, these regimens are associated with significant oxaliplatin-induced neurotoxicity. The results of the recent IDEA study provide evidence that 3 months of treatment with CAPOX is as effective as 6 months of oxaliplatin-based therapy in patients with low-risk stage III CC (T1-3 and N1). A 6-month oxaliplatin-based therapy remains the standard of care for high-risk stage III CC (T4 and/or N2). For patients unfit for oxaliplatin, fluoropyrimidine monotherapy is recommended.

CONCLUSION

French guidelines for non-metastatic CC management help to offer the best personalized therapeutic strategy in daily clinical practice. Each individual case must be discussed within a multidisciplinary tumor board and then the treatment option decided with the patient.

Identification of people with Lynch syndrome from those presenting with colorectal cancer in England: baseline analysis of the diagnostic pathway

It is believed that >95% of people with Lynch syndrome (LS) remain undiagnosed. Within the National Health Service (NHS) in England, formal guidelines issued in 2017 state that all colorectal cancers (CRC) should be tested for DNA Mismatch Repair deficiency (dMMR). We used a comprehensive population-level national dataset to analyse implementation of the agreed diagnostic pathway at a baseline point 2 years post-publication of official guidelines. Using real-world data collected and curated by the National Cancer Registration and Analysis Service (NCRAS), we retrospectively followed up all people diagnosed with CRC in England in 2019. Nationwide laboratory diagnostic data incorporated somatic (tumour) testing for dMMR (via immunohistochemistry or microsatellite instability), somatic testing for MLH1 promoter methylation and BRAF status, and constitutional (germline) testing of MMR genes. Only 44% of CRCs were screened for dMMR; these figures varied over four-fold with respect to geography. Of those CRCs identified as dMMR, only 51% underwent subsequent diagnostic testing. Overall, only 1.3% of patients with colorectal cancer had a germline MMR genetic test performed; up to 37% of these tests occurred outside of NICE guidelines. The low rates of molecular diagnostic testing in CRC support the premise that Lynch syndrome is underdiagnosed, with significant attrition at all stages of the testing pathway. Applying our methodology to subsequent years' data will allow ongoing monitoring and analysis of the impact of recent investment. If the diagnostic guidelines were fully implemented, we estimate that up to 700 additional people with LS could be identified each year.

The experience of receiving a letter from a cancer genetics clinic about risk for hereditary cancer

Direct contact may be an option for supporting disclosure in families with hereditary cancer risk. In this qualitative interview study, we explored how healthy at-risk relatives experience receiving a letter with information about hereditary cancer directly from healthcare rather than via a relative. The study is part of an ongoing multicentre randomised clinical trial in Sweden that evaluates the effectiveness of direct letters from cancer genetics clinics to at-risk relatives. After conducting semi-structured interviews with 14 relatives who had received a letter and contacted the clinic, we analysed the data using thematic analysis. The relatives had different levels of prior knowledge about the hereditary cancer assessment. Many had been notified by family that a letter was coming but some had not. Overall, these participants believed healthcare-mediated disclosure could complement family-mediated disclosure. They expressed that the letter and the message raised concerns and a need for counselling, and they wanted healthcare to be accessible and informed when making contact. The participants found the message easier to cope with when they had been notified by a family member beforehand, with a general attitude that notifying relatives was the appropriate step to take. They thought healthcare should help patients with the disclosure process but also guard the right of at-risk relatives to be informed. The findings support a direct approach from healthcare as a possible complement to an established model of family-mediated risk disclosure, but implementation must be made within existing frameworks of good practice for genetic counselling.

Psychiatric and Educational Aspects of Familial Adenomatous Polyposis: A Nationwide Danish Cohort Study With Matched Nonexposed Individuals

INTRODUCTION

Familial adenomatous polyposis (FAP) is an autosomal, dominantly inherited disorder that predisposes to colorectal cancer. An increased risk of cancer may affect mental health, but the magnitude of this effect remains unknown. We assessed the psychosocial functioning, including the educational level attained and risk of psychiatric comorbidity, of patients with FAP by comparing them with matched nonexposed individuals.

METHODS

All Danish patients with FAP diagnosed before April 2021 were identified in the Danish Polyposis Register and paired with 4 matched nonexposed individuals. Educational history, psychiatric contacts or diagnoses ( International Classification of Disease, 10th Revision ), and treatment with antidepressants, anxiolytics, or antipsychotics were compared between patients with FAP and nonexposed individuals.

RESULTS

The analysis included 445 patients with FAP and 1,538 nonexposed individuals. The highest educational level reached was significantly lower for patients with FAP ( P < 0.001). When comparing patients with FAP and nonexposed and adjusting for a cancer diagnosis, an increased risk was observed for a psychiatric contact (1.69, 95% confidence interval [CI] 1.25-2.29, P < 0.001), any psychiatric prescription (1.39, 95% CI 1.17-1.66, P < 0.001), a psychiatric diagnosis (1.64, 95% CI 1.19-2.26, P = 0.002), and experiencing any psychiatric event (hazard ratio 1.42, 95% CI 1.20-1.68, P < 0.001). An increased risk was specifically seen for mood (affective) disorders (1.76, 95% CI 1.09-2.83, P = 0.02) and behavioral and emotional disorders (2.01, 95% CI 1.10-3.69, P = 0.02) and the need for antidepressants (1.59, 95% CI 1.24-2.03, P < 0.001) and antipsychotics (1.85, 95% CI 1.26-2.70, P = 0.002).

DISCUSSION

Compared with nonexposed individuals, patients with had significantly less education and an increased risk of developing mood and behavioral disorders, with an increased likelihood of needing antidepressants and antipsychotics.

Curative resection via right hemicolectomy and regional lymph node dissection for colonic adenomatous polyposis of unknown etiology with adenocarcinomas localized in the right side of the colon: a case report

BACKGROUND

APC and MUTYH are both well-known colorectal polyposis causative genes. However, 30-50% of colorectal adenomatous polyposis cases are classified as colonic adenomatous polyposis of unknown etiology and lack identifiable pathogenic variants. Although guidelines recommend total proctocolectomy for colonic adenomatous polyposis of unknown etiology with over 100 adenomas, evidence is lacking. This study presents a unique case of localized colonic adenomatous polyposis of unknown etiology with multiple adenocarcinomas, treated with hemicolectomy and regional lymph node dissection.

CASE PRESENTATION

The patient was a 72-year-old woman whose colonoscopy revealed numerous polyps and two adenocarcinomas localized in the right side of the colon, with no lesions in the left side. The patient had no family history of polyposis or colorectal cancer. No extracolonic lesions, enlarged lymph nodes, or distant metastases were found. Considering the patient's age and lesion localization, laparoscopic right hemicolectomy with regional lymph node dissection was performed. Histopathological diagnosis revealed three adenocarcinoma lesions with no lymph node metastasis. The most advanced pathological stage was T2N0M0 Stage I (UICC 8th edition). The patient was alive 5 years postoperatively, without recurrence of cancer or polyposis in the remaining colon and rectum. To diagnose hereditary colorectal cancer/polyposis, a germline multigene panel testing for APC, EPCAM, MBD4, MLH1, MLH3, MSH2, MSH3, MSH6, MUTYH, NTHL1, PMS2, POLD1, POLE, and TP53 was performed using DNA extracted from blood samples: however, no pathogenic variant was detected. Therefore, the patient was diagnosed with colonic adenomatous polyposis of unknown etiology.

CONCLUSIONS

In this rare case, colonic adenomatous polyposis of unknown etiology, with numerous adenomatous polyps and multiple adenocarcinomas localized in the right side of the colon, was successfully treated with right hemicolectomy and regional lymph node dissection. Despite genetic analysis, no causative germline variants were identified. Segmental colectomy according to the distribution of polyps might be a curative approach.

Two missense STK11 gene variations impaired LKB1/adenosine monophosphate-activated protein kinase signaling in Peutz-Jeghers syndrome

BACKGROUND

Peutz-Jeghers syndrome (PJS) is a rare hereditary neoplastic disorder mainly associated with serine/threonine kinase 11 (STK11/LKB1) gene mutations. Preimplantation genetic testing can protect a patient's offspring from mutated genes; however, some variations in this gene have been interpreted as variants of uncertain significance (VUS), which complicate reproductive decision-making in genetic counseling.

AIM

To identify the pathogenicity of two missense variants and provide clinical guidance.

METHODS

Whole exome gene sequencing and Sanger sequencing were performed on the peripheral blood of patients with PJS treated at the Reproductive and Genetic Hospital of Citic-Xiangya. Software was employed to predict the protein structure, conservation, and pathogenicity of the two missense variation sites in patients with PJS. Additionally, plasmids were constructed and transfected into HeLa cells to observe cell growth. The differences in signal pathway expression between the variant group and the wild-type group were compared using western blot and immunohistochemistry. Statistical analysis was performed using one-way analysis of variance. P < 0.05 was considered statistically significant.

RESULTS

We identified two missense STK11 gene VUS [c.889A>G (p.Arg297Gly) and c.733C>T (p.Leu245Phe)] in 9 unrelated PJS families who were seeking reproductive assistance. The two missense VUS were located in the catalytic domain of serine/threonine kinase, which is a key structure of the liver kinase B1 (LKB1) protein. In vitro experiments showed that the phosphorylation levels of adenosine monophosphate-activated protein kinase (AMPK) at Thr172 and LKB1 at Ser428 were significantly higher in transfected variation-type cells than in wild-type cells. In addition, the two missense STK11 variants promoted the proliferation of HeLa cells. Subsequent immunohistochemical analysis showed that phosphorylated-AMPK (Thr172) expression was significantly lower in gastric, colonic, and uterine polyps from PJS patients with missense variations than in non-PJS patients. Our findings indicate that these two missense STK11 variants are likely pathogenic and inactivate the STK11 gene, causing it to lose its function of regulating downstream phosphorylated-AMPK (Thr172), which may lead to the development of PJS. The identification of the pathogenic mutations in these two clinically characterized PJS patients has been helpful in guiding them toward the most appropriate mode of pregnancy assistance.

CONCLUSION

These two missense variants can be interpreted as likely pathogenic variants that mediated the onset of PJS in the two patients. These findings not only offer insights for clinical decision-making, but also serve as a foundation for further research and reanalysis of missense VUS in rare diseases.

The genomics of sporadic and hereditary colorectal cancer

Colorectal cancer (CRC) is a leading cause of cancer deaths worldwide. Over the past three decades, extensive efforts have sought to elucidate the genomic landscape of CRC. These studies reveal that CRC is highly heterogeneous at the molecular level, with different subtypes characterised by distinct somatic mutational profiles, epigenetic aberrations and transcriptomic signatures. This review summarises our current understanding of the genomic and epigenomic alterations implicated in CRC development and progression. Particular focus is given to how characterisation of CRC genomes is leading to more personalised approaches to diagnosis and treatment.

The Spigelman Staging System and the Risk of Duodenal and Papillary Cancer in Familial Adenomatous Polyposis: A Systematic Review and Meta-Analysis

INTRODUCTION

Individuals with familial adenomatous polyposis (FAP) have an almost 20% lifetime risk of duodenal adenocarcinoma, currently the leading cause of death in FAP. The Spigelman staging system provides guidance on the surveillance intervals and timing of prophylactic surgery. Still, its accuracy in predicting duodenal and papillary cancer development has not been systematically evaluated. We investigated the sensitivity and cancer risk of the Spigelman stages.

METHODS

We performed a systematic review on PubMed, MEDLINE, EMBASE, and Cochrane and used a random-effects model to pool effect sizes.

RESULTS

After removing duplicate entries, we screened 1,170 records and included 27 studies for quantitative analysis. Once duodenal polyposis reaches Spigelman stage IV, the risk of duodenal and papillary cancers increased to 25% (95% confidence interval [CI] 12%-45%). However, the sensitivity of Spigelman stage IV for these cancers was low (51%, 95% CI 42%-60%), especially for papillary adenocarcinoma (39%, 95% CI 16%-68%). We investigated the reasons behind these low values and observed that duodenal cancer risk factors included polyps >10 mm, polyp count >20, and polyps with high-grade dysplasia. Risk factors associated with papillary cancer included a papilla with high-grade dysplasia or >10 mm. The evidence on other risk factors was inconclusive.

DISCUSSION

The current Spigelman staging system had a low sensitivity for duodenal and papillary adenocarcinomas. Two Spigelman variables (duodenal villous histology and polyp count) and the lack of papilla-specific variables likely contributed to the low sensitivity values for duodenal and papillary cancers, respectively. While clinicians may be familiar with its current form, there is an urgent need to update it.

Screening and surveillance for hereditary colorectal cancer

Hereditary colorectal cancer is a type of cancer that is caused by a genetic mutation. Individuals with a family history of colorectal cancer, or who have a known hereditary syndrome, are at an increased risk of developing the disease. Screening and surveillance are important tools for managing the risk of hereditary colorectal cancer. Screening involves a combination of tests that can detect precancerous or cancerous changes in the colon and rectum. Surveillance involves regular follow-up examinations to monitor disease progression and to identify new developments. The frequency and type of screening and surveillance tests may vary depending on an individual's risk factors, genetic profile, and medical history. However, early detection and treatment of hereditary colorectal cancer can significantly improve patient outcomes and reduce mortality rates. By implementing comprehensive screening and surveillance strategies, healthcare providers can help individuals at risk of hereditary colorectal cancer to receive timely interventions and make informed decisions about their health. Specific examples of screening and surveillance tests for hereditary colorectal cancer include colonoscopy, genetic testing, and imaging tests. In this review article, we will discuss detailed screening and surveillance of hereditary colorectal cancer.

Patients' perceptions and practices of informing relatives: a qualitative study within a randomised trial on healthcare-assisted risk disclosure

In a multicentre randomised controlled trial (DIRECT), we evaluate whether an intervention of providing direct letters from healthcare professionals to at-risk relatives (ARRs) affects the proportion of ARRs contacting a cancer genetics clinic, compared with patient-mediated disclosure alone (control). With the aim to explore how the patients included in the trial perceived and performed risk communication with their ARRs we analysed 17 semi-structured interviews with reflexive thematic analysis. All patients described that they disclosed risk information to all close relatives themselves. No integrity-related issues were reported by patients offered the intervention, and all of them accepted direct letters to all their ARRs. Patients' approaches to informing distant relatives were unpredictable and varied from contacting all distant ARRs, sharing the burden with the family, utilising the offer of sending direct letters, vaguely relying on others to inform, or postponing disclosure. Most patients limited their responsibility to the disclosure, although others wanted relatives to get genetic counselling or felt a need to provide additional information to the ARRs before ending their mission. We also identified confusion about the implication of test results, who needed risk information, and who was responsible for informing ARRs. These misunderstandings possibly also affected risk disclosure. This study revealed that despite accepting the direct letters to be sent to all relatives, the patients also contributed to risk disclosure in other ways. It was only in some situations to distant relatives that the healthcare-assisted letter was the only means of communication to the ARRs.

Tumor analysis of MMR genes in Lynch-like syndrome: Challenges associated with results interpretation

BACKGROUND

Up to 70% of suspected Lynch syndrome patients harboring MMR deficient tumors lack identifiable germline pathogenic variants in MMR genes, being referred to as Lynch-like syndrome (LLS). Previous studies have reported biallelic somatic MMR inactivation in a variable range of LLS-associated tumors. Moreover, translating tumor testing results into patient management remains controversial. Our aim is to assess the challenges associated with the implementation of tumoral MMR gene testing in routine workflows.

METHODS

Here, we present the clinical characterization of 229 LLS patients. MMR gene testing was performed in 39 available tumors, and results were analyzed using two variant allele frequency (VAF) thresholds (≥5% and ≥10%).

RESULTS AND DISCUSSION

More biallelic somatic events were identified at VAF ≥ 5% than ≥10% (35.9% vs. 25.6%), although the rate of nonconcordant results regarding immunohistochemical pattern increased (30.8% vs. 20.5%). Interpretation difficulties question the current utility of the identification of MMR somatic hits in the diagnostic algorithm of suspected LS cases.

Screening and prevention of ovarian cancer

Ovarian cancer remains the most lethal gynaecological malignancy with 314 000 cases and 207 000 deaths annually worldwide. Ovarian cancer cases and deaths are predicted to increase in Australia by 42% and 55% respectively by 2040. Earlier detection and significant downstaging of ovarian cancer have been demonstrated with multimodal screening in the largest randomised controlled trial of ovarian cancer screening in women at average population risk. However, none of the randomised trials have demonstrated a mortality benefit. Therefore, ovarian cancer screening is not currently recommended in women at average population risk. More frequent surveillance for ovarian cancer every three to four months in women at high risk has shown good performance characteristics and significant downstaging, but there is no available information on a survival benefit. Population testing offers an emerging novel strategy to identify women at high risk who can benefit from ovarian cancer prevention. Novel multicancer early detection biomarker, longitudinal multiple marker strategies, and new biomarkers are being investigated and evaluated for ovarian cancer screening. Risk-reducing salpingo-oophorectomy (RRSO) decreases ovarian cancer incidence and mortality and is recommended for women at over a 4-5% lifetime risk of ovarian cancer. Pre-menopausal women without contraindications to hormone replacement therapy (HRT) undergoing RRSO should be offered HRT until 51 years of age to minimise the detrimental consequences of premature menopause. Currently risk-reducing early salpingectomy and delayed oophorectomy (RRESDO) should only be offered to women at increased risk of ovarian cancer within the context of a research trial. Pre-menopausal early salpingectomy is associated with fewer menopausal symptoms and better sexual function than bilateral salpingo-oophorectomy. A Sectioning and Extensively Examining the Fimbria (SEE-FIM) protocol should be used for histopathological assessment in women at high risk of ovarian cancer who are undergoing surgical prevention. Opportunistic salpingectomy may be offered at routine gynaecological surgery to all women who have completed their family. Long term prospective opportunistic salpingectomy studies are needed to determine the effect size of ovarian cancer risk reduction and the impact on menopause.

Genome-wide polygenic risk scores for colorectal cancer have implications for risk-based screening

BACKGROUND

Hereditary factors, including single genetic variants and family history, can be used for targeting colorectal cancer (CRC) screening, but limited data exist on the impact of polygenic risk scores (PRS) on risk-based CRC screening.

METHODS

Using longitudinal health and genomics data on 453,733 Finnish individuals including 8801 CRC cases, we estimated the impact of a genome-wide CRC PRS on CRC screening initiation age through population-calibrated incidence estimation over the life course in men and women.

RESULTS

Compared to the cumulative incidence of CRC at age 60 in Finland (the current age for starting screening in Finland), a comparable cumulative incidence was reached 5 and 11 years earlier in persons with high PRS (80-99% and >99%, respectively), while those with a low PRS (< 20%) reached comparable incidence 7 years later. The PRS was associated with increased risk of post-colonoscopy CRC after negative colonoscopy (hazard ratio 1.76 per PRS SD, 95% CI 1.54-2.01). Moreover, the PRS predicted colorectal adenoma incidence and improved incident CRC risk prediction over non-genetic risk factors.

CONCLUSIONS

Our findings demonstrate that a CRC PRS can be used for risk stratification of CRC, with further research needed to optimally integrate the PRS into risk-based screening.

Mosaic Muir Torre Syndrome: Keratoacanthoma as a Piece of the Puzzle

ABSTRACT

Lynch syndrome is an inherited condition, which increases the risk of numerous visceral malignancies and cutaneous tumors such as keratoacanthomas and sebaceous tumors. It is typically identified by immunohistochemistry of tissue taken from tumors or through genetic testing with next-generation sequencing. Diagnosing Lynch syndrome becomes more complex when the individual is mosaic for the relevant pathogenic variant. There are very few cases of this reported in the medical literature. It is even more unusual for the diagnosis to be made based on testing of a keratoacanthoma lesion. We report a case where immunohistochemistry of a keratoacanthoma helped make a diagnosis of mosaic Lynch syndrome. We will explore how mosaicism should be considered when a phenotype is strong, even if next-generation sequencing reports no pathogenic or likely pathogenic variant and how lesions such as keratoacanthomas can have a role in the early detection and treatment of future malignancies.

The comprehensive English National Lynch Syndrome Registry: development and description of a new genomics data resource

Background

Lynch Syndrome (LS) is a cancer predisposition syndrome caused by constitutional pathogenic variants in the mismatch repair (MMR) genes. To date, fragmentation of clinical and genomic data has restricted understanding of national LS ascertainment and outcomes, and precluded evaluation of NICE guidance on testing and management. To address this, via collaboration between researchers, the National Disease Registration Service (NDRS), NHS Genomic Medicine Service Alliances (GMSAs), and NHS Regional Clinical Genetics Services, a comprehensive registry of LS carriers in England has been established.

Methods

For comprehensive ascertainment of retrospectively identified MMR pathogenic variant (PV) carriers (diagnosed prior to January 1, 2023), information was retrieved from all clinical genetics services across England, then restructured, amalgamated, and validated via a team of trained experts in NDRS. An online submission portal was established for prospective ascertainment from January 1, 2023. The resulting data, stored in a secure database in NDRS, were used to investigate the demographic and genetic characteristics of the cohort, censored at July 25, 2023. Cancer outcomes were investigated via linkage to the National Cancer Registration Dataset (NCRD).

Findings

A total of 11,722 retrospective and 570 prospective data submissions were received, resulting in a comprehensive English National Lynch Syndrome Registry (ENLSR) comprising 9030 unique individuals. The most frequently identified pathogenic MMR genes were MSH2 and MLH1 at 37.2% (n = 3362) and 29.1% (n = 2624), respectively. 35.9% (n = 3239) of the ENLSR cohort received their LS diagnosis before their first cancer diagnosis (presumptive predictive germline test). Of these, 6.3% (n = 204) developed colorectal cancer, at a median age of initial diagnosis of 51 (IQR 40-62), compared to 73 years (IQR 64-80) in the general population (p < 0.0001).

Interpretation

The ENLSR represents the first comprehensive national registry of PV carriers in England and one of the largest cohorts of MMR PV carriers worldwide. The establishment of a secure, centralised infrastructure and mechanism for routine registration of newly identified carriers ensures sustainability of the data resource.

Funding

This work was funded by the Wellcome Trust, Cancer Research UK and Bowel Cancer UK. The funder of this study had no role in study design, data collection, data analysis, data interpretation, or writing of the report.

Molecular and Clinicopathologic Characterization of Mismatch Repair-Deficient Endometrial Carcinoma Not Related to MLH1 Promoter Hypermethylation

Universal tumor screening in endometrial carcinoma (EC) is increasingly adopted to identify individuals at risk of Lynch syndrome (LS). These cases involve mismatch repair-deficient (MMRd) EC without MLH1 promoter hypermethylation (PHM). LS is confirmed through the identification of germline MMR pathogenic variants (PV). In cases where these are not detected, emerging evidence highlights the significance of double-somatic MMR gene alterations as a sporadic cause of MMRd, alongside POLE/POLD1 exonuclease domain (EDM) PV leading to secondary MMR PV. Our understanding of the incidence of different MMRd EC origins not related to MLH1-PHM, their associations with clinicopathologic characteristics, and the prognostic implications remains limited. In a combined analysis of the PORTEC-1, -2, and -3 trials (n = 1254), 84 MMRd EC not related to MLH1-PHM were identified that successfully underwent paired tumor-normal tissue next-generation sequencing of the MMR and POLE/POLD1 genes. Among these, 37% were LS associated (LS-MMRd EC), 38% were due to double-somatic hits (DS-MMRd EC), and 25% remained unexplained. LS-MMRd EC exhibited higher rates of MSH6 (52% vs 19%) or PMS2 loss (29% vs 3%) than DS-MMRd EC, and exclusively showed MMR-deficient gland foci. DS-MMRd EC had higher rates of combined MSH2/MSH6 loss (47% vs 16%), loss of >2 MMR proteins (16% vs 3%), and somatic POLE-EDM PV (25% vs 3%) than LS-MMRd EC. Clinicopathologic characteristics, including age at tumor onset and prognosis, did not differ among the various groups. Our study validates the use of paired tumor-normal next-generation sequencing to identify definitive sporadic causes in MMRd EC unrelated to MLH1-PHM. MMR immunohistochemistry and POLE-EDM mutation status can aid in the differentiation between LS-MMRd EC and DS-MMRd EC. These findings emphasize the need for integrating tumor sequencing into LS diagnostics, along with clear interpretation guidelines, to improve clinical management. Although not impacting prognosis, confirmation of DS-MMRd EC may release patients and relatives from burdensome LS surveillance.

Use of multi-gene panels in patients at high risk of hereditary digestive cancer: position statement of AEG, SEOM, AEGH and IMPaCT-GENÓMICA consortium

This position statement, sponsored by the Asociación Española de Gastroenterología, the Sociedad Española de Oncología Médica, the Asociación Española de Genética Humana and the IMPaCT-Genómica Consortium aims to establish recommendations for use of multi-gene panel testing in patients at high risk of hereditary gastrointestinal and pancreatic cancer. To rate the quality of the evidence and the levels of recommendation, we used the methodology based on the GRADE system (Grading of Recommendations Assessment, Development and Evaluation). We reached a consensus among experts using a Delphi method. The document includes recommendations on clinical scenarios where multi-gene panel testing is recommended in colorectal cancer, polyposis syndromes, gastric and pancreatic cancer, as well as the genes to be considered in each clinical scenario. Recommendations on the evaluation of mosaicisms, counseling strategies in the absence of an index subject and, finally, constitutional analysis after identification of pathogenic tumor variants are also made.

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.

Clinical efficacy of metformin in familial adenomatous polyposis and the effect of intestinal flora

BACKGROUND AND AIMS

Metformin has been reported to inhibit the occurrence and development of colorectal cancer (CRC) by mediating changes in intestinal flora. Studies have also indicated that the occurence of familial adenomatous polyposis (FAP) may also be associated with changes in the intestinal flora. Therefore, we investigated the efficacy and safety of metformin in treating FAP and the association with intestinal flora.

RESULTS

Compared with the baseline, the mean number and load of polyps in the areas of nanocarbon labeling and postoperative residuals in the test group were lower than those in the placebo group, while the diversity of intestinal flora species was increased. At the genus level, the relative abundance of g_Ruminococcus in the test group was lower than that at baseline, whereas the relative abundance of g_Lactobacillus was higher. These changes were statistically significant (P < 0.05).

CONCLUSION

One-year metformin therapy for FAP is safe and effective, potentially mediated by modulating the intestinal flora. This study provides new insights and strategies for preventing adenomatous polyp carcinogenesis in FAP and explores possible preventive action.

Lynch Syndrome: From Multidisciplinary Management to Precision Prevention

BACKGROUND AND AIMS

Lynch syndrome (LS) is currently one of the most prevalent hereditary cancer conditions, accounting for 3% of all colorectal cancers and for up to 15% of those with DNA mismatch repair (MMR) deficiency, and it was one of the first historically identified. The understanding of the molecular carcinogenesis of LS tumors has progressed significantly in recent years. We aim to review the most recent advances in LS research and explore genotype-based approaches in surveillance, personalized cancer prevention, and treatment strategies.

METHODS

PubMed was searched to identify relevant studies, conducted up to December 2023, investigating molecular carcinogenesis in LS, surveillance strategies, cancer prevention, and treatment in LS tumors.

RESULTS

Multigene panel sequencing is becoming the benchmark in the diagnosis of LS, allowing for the detection of a pathogenic constitutional variant in one of the MMR genes. Emerging data from randomized controlled trials suggest possible preventive roles of resistant starch and/or aspirin in LS. Vaccination with immunogenic frameshift peptides appears to be a promising approach for both the treatment and prevention of LS-associated cancers, as evidenced by pre-clinical and preliminary phase 1/2a studies.

CONCLUSIONS

Although robust diagnostic algorithms, including prompt testing of tumor tissue for MMR defects and referral for genetic counselling, currently exist for suspected LS in CRC patients, the indications for LS screening in cancer-free individuals still need to be refined and standardized. Investigation into additional genetic and non-genetic factors that may explain residual rates of interval cancers, even in properly screened populations, would allow for more tailored preventive strategies.

Treatment of Complex Desmoid Tumors in Familial Adenomatous Polyposis Syndrome by Intestinal Transplantation

Background

Desmoid tumors are fibroblastic lesions which often have an unpredictable and variable clinical course. In the context of familial adenomatous polyposis (FAP), these frequently occur intra-abdominally, especially in the small-bowel mesentery resulting in sepsis, fistulation, and invasion of the abdominal wall and retroperitoneum. In selected cases where other modalities have failed, the most radical option is to perform a total enterectomy and intestinal transplantation (ITx). In this study, we present our center's experience of ITx for desmoid in patients with FAP.

Methods

We performed a retrospective review of our prospectively collected database between 2007 and 2022. All patients undergoing ITx for FAP-related desmoid were included.

Results

Between October 2007 and September 2023, 144 ITx were performed on 130 patients at our center. Of these, 15 patients (9%) were for desmoid associated with FAP (7 modified multivisceral transplants, 6 isolated ITx, and 2 liver-containing grafts). The median follow-up was 57 mo (8-119); 5-y patient survival was 82%, all with functioning grafts without local desmoid recurrence. These patients presented us with several complex surgical issues, such as loss of abdominal domain, retroperitoneal/abdominal wall involvement, ileoanal pouch-related issues, and the need for foregut resection because of adenomatous disease.

Conclusions

ITx is a viable treatment in selected patients with FAP and extensive desmoid disease. The decision to refer for ITx can be challenging, particularly the timing and sequence of treatment (simultaneous versus sequential exenteration). Delays can result in additional disease burden, such as secondary liver disease or invasion of adjacent structures.

Gene-specific ACMG/AMP classification criteria for germline APC variants: Recommendations from the ClinGen InSiGHT Hereditary Colorectal Cancer/Polyposis Variant Curation Expert Panel

PURPOSE

The Hereditary Colorectal Cancer/Polyposis Variant Curation Expert Panel (VCEP) was established by the International Society for Gastrointestinal Hereditary Tumours and the Clinical Genome Resource, who set out to develop recommendations for the interpretation of germline APC variants underlying Familial Adenomatous Polyposis, the most frequent hereditary polyposis syndrome.

METHODS

Through a rigorous process of database analysis, literature review, and expert elicitation, the APC VCEP derived gene-specific modifications to the ACMG/AMP (American College of Medical Genetics and Genomics and Association for Molecular Pathology) variant classification guidelines and validated such criteria through the pilot classification of 58 variants.

RESULTS

The APC-specific criteria represented gene- and disease-informed specifications, including a quantitative approach to allele frequency thresholds, a stepwise decision tool for truncating variants, and semiquantitative evaluations of experimental and clinical data. Using the APC-specific criteria, 47% (27/58) of pilot variants were reclassified including 14 previous variants of uncertain significance (VUS).

CONCLUSION

The APC-specific ACMG/AMP criteria preserved the classification of well-characterized variants on ClinVar while substantially reducing the number of VUS by 56% (14/25). Moving forward, the APC VCEP will continue to interpret prioritized lists of VUS, the results of which will represent the most authoritative variant classification for widespread clinical use.

Clinical features and distribution of the APC variant in duodenal and ampullary polyps in patients with familial adenomatous polyposis: a multicenter retrospective cohort study in Japan

BACKGROUND

Management of duodenal or ampullary adenomas in patients with familial adenomatous polyposis (FAP) is a major challenge for clinicians. Insufficient data are available to evaluate the clinical manifestations and distribution of adenomatous polyposis coli (APC) variants in these patients.

METHODS

We enrolled 451 patients with data regarding duodenal or ampullary polyps from 632 patients with FAP retrospectively registered in a nationwide Japanese multicenter study. Clinicopathological features and distribution of APC variants were compared between patients with and without duodenal or ampullary polyps.

RESULTS

Duodenal and ampullary polyps were found in 59% and 18% of patients with FAP, respectively. The incidence of duodenal cancer was 4.7% in patients with duodenal polyps, and that of ampullary cancer was 18% in patients with ampullary polyps. Duodenal polyps were significantly associated with the presence of ampullary polyps and jejunal/ileal polyps. Duodenal polyps progressed in 35% of patients with a median follow-up of 776 days, mostly in those with early Spigelman stage lesions. Ampullary polyps progressed in 50% of patients with a follow-up of 1484 days. However, only one patient developed a malignancy. The proportion of patients with duodenal polyps was significantly higher among those with intermediate- or profuse-type APC variants than attenuated-type APC variants. The presence of duodenal polyps was significantly associated with ampullary and jejunal/ileal polyps in patients with intermediate- or profuse-type APC variants.

CONCLUSIONS

Periodic endoscopic surveillance of the papilla of Vater and small intestine should be planned for patients with FAP with duodenal polyps.

Differential Diagnoses and Management Approaches for Gastric Polyposis

Multiple gastric polyps are observed in various polyposis syndromes and conditions associated with polypoid lesion development in the stomach. Polyposis syndromes often occur concurrently with specific malignant tumors and can manifest at any point in an individual’s lifespan, thus explaining the diversity in surveillance methods. Furthermore, genetic counseling and surveillance are essential not only for the patients themselves but also for their blood relatives. Therefore, the accurate diagnosis and appropriate surveillance of multiple gastric polyps are crucial for improving patient outcomes. This review aims to provide essential information on such lesions along with representative endoscopic images of familial adenomatous polyposis, Peutz-Jeghers syndrome, Cowden syndrome, Cronkhite-Canada syndrome, juvenile polyposis syndrome, gastric adenocarcinoma and proximal polyposis of the stomach, neuroendocrine tumors in autoimmune gastritis, proton pump inhibitor-related gastric mucosal changes, and multiple submucosal heterotopic glands. We wish for this review to serve as a valuable resource for endoscopists seeking to deepen their comprehension of gastric polyposis.

Colorectal cancer: Genetic alterations, novel biomarkers, current therapeutic strategies and clinical trials

Colorectal cancer (CRC) is the third most commonly detected cancer with a serious global health issue. The rates for incidence and mortality for CRC are alarming, especially since the prognosis is abysmal when the CRC is diagnosed at an advanced or metastatic stage. Both type of (modifiable/ non-modifiable) types of risk factors are established for CRC. Despite the advances in recent technology and sophisticated research, the survival rate is still meager due to delays in diagnosis. Therefore, there is urgently required to identify critical biomarkers aiming at early diagnosis and improving effective therapeutic strategies. Additionally, a complete understanding of the dysregulated pathways like PI3K/Akt, Notch, and Wnt associated with CRC progression and metastasis is very beneficial in designing a therapeutic regimen. This review article focused on the dysregulated signaling pathways, genetics and epigenetics alterations, and crucial biomarkers of CRC. This review also provided the list of clinical trials targeting signaling cascades and therapies involving small molecules. This review discusses up-to-date information on novel diagnostic and therapeutic strategies alongside specific clinical trials.

Cumulative Absolute Risk of Subsequent Colorectal Cancer After Abdominopelvic Radiotherapy Among Childhood Cancer Survivors: A PanCareSurFup Study

PURPOSE

Childhood cancer survivors are at the risk of developing subsequent colorectal cancers (CRCs), but the absolute risks by treatment modality are uncertain. We quantified the absolute risks by radiotherapy treatment characteristics using clinically accessible data from a Pan-European wide case-control study nested within a large cohort of childhood cancer survivors: the PanCareSurFup Study.

METHODS

Odds ratios (ORs) from a case-control study comprising 143 CRC cases and 143 controls nested within a cohort of 69,460 survivors were calculated. These, together with standardized incidence ratios for CRC for this cohort and European general population CRC incidence rates and survivors' mortality rates, were used to estimate cumulative absolute risks (CARs) by attained age for different categories of radiation to the abdominopelvic area.

RESULTS

Overall, survivors treated with abdominopelvic radiotherapy treatment (ART) were three times more likely to develop a subsequent CRC than those who did not receive ART (OR, 3.1 [95% CI, 1.4 to 6.6]). For male survivors treated with ART, the CAR was 0.27% (95% CI, 0.17 to 0.59) by age 40 years, 1.08% (95% CI, 0.69 to 2.34) by age 50 years (0.27% expected in the general population), and 3.7% (95% CI, 2.36 to 7.80) by age 60 years (0.95% expected). For female survivors treated with ART, the CAR was 0.29% (95% CI, 0.18 to 0.62) by age 40 years, 1.03% (95% CI, 0.65 to 2.22) by age 50 years (0.27% expected), and 3.0% (95% CI, 1.91 to 6.37) by age 60 years (0.82% expected).

CONCLUSION

We demonstrated that by age 40 years survivors of childhood cancer treated with ART already have a similar risk of CRC as those age 50 years in the general population for whom population-based CRC screening begins in many countries. This information should be used in the development of survivorship guidelines for the risk stratification of survivors concerning CRC risk.

Co-design of patient information leaflets for germline predisposition to cancer: recommendations for clinical practice from the UK Cancer Genetics Group (UKCGG), Cancer Research UK (CRUK) funded CanGene-CanVar Programme and the Association of Genetic Nurse Counsellors (AGNC)

BACKGROUND

Testing for germline pathogenic variants (GPVs) in cancer predisposition genes is increasingly offered as part of routine care for patients with cancer. This is often urgent in oncology clinics due to potential implications on treatment and surgical decisions. This also allows identification of family members who should be offered predictive genetic testing. In the UK, it is common practice for healthcare professionals to provide a patient information leaflet (PIL) at point of care for diagnostic genetic testing in patients with cancer, after results disclosure when a GPV is identified, and for predictive testing of at-risk relatives. Services usually create their own PIL, resulting in duplication of effort and wide variability regarding format, content, signposting and patient input in co-design and evaluation.

METHODS

Representatives from UK Cancer Genetics Group (UKCGG), Cancer Research UK (CRUK) funded CanGene-CanVar programme and Association of Genetic Nurse Counsellors (AGNC) held a 2-day meeting with the aim of making recommendations for clinical practice regarding co-design of PIL for germline cancer susceptibility genetic testing. Lynch syndrome and haematological malignancies were chosen as exemplar conditions.

RESULTS

Meeting participants included patient representatives including as co-chair, multidisciplinary clinicians and other experts from across the UK. High-level consensus for UK recommendations for clinical practice was reached on several aspects of PIL using digital polling, including that PIL should be offered, accessible, co-designed and evaluated with patients.

CONCLUSIONS

Recommendations from the meeting are likely to be applicable for PIL co-design for a wide range of germline genetic testing scenarios.

Microsatellite Instability Is Insufficiently Used as a Biomarker for Lynch Syndrome Testing in Clinical Practice

PURPOSE

The pan-cancer presence of microsatellite instability (MSI)-positive tumors demonstrates its clinical utility as an agnostic biomarker for identifying immunotherapy-eligible patients. Additionally, MSI is a hallmark of Lynch syndrome (LS), the most prevalent cancer susceptibility syndrome among patients with colorectal and endometrial cancer. Therefore, MSI-high results should inform germline genetic testing for cancer-predisposing genes. However, in clinical practice, such analysis is frequently disregarded.

METHODS

A next-generation sequencing (NGS)-based technique was used for MSI analysis in 4,553 patients with various tumor types. Upon request, somatic BRAF gene analysis was conducted. In addition, hereditary testing of cancer-associated genes was performed in MSI-high cases using a capture-based NGS protocol. MLH1 promoter methylation analysis was conducted retrospectively in patients with colorectal and endometrial cancer to further investigate the origin of MSI at the tumor level.

RESULTS

The MSI positivity rate for the entire cohort was 5.27%. Endometrial, gastric, colorectal, urinary tract, and prostate cancers showed the highest proportion of MSI-high cases (15.69%, 8.54%, 7.40%, 4.55%, and 3.19%, respectively). A minority of 45 patients (22.73%) among the MSI-high cases underwent germline testing to determine whether the mismatch repair pathway deficiency was inherited. 24.44% of those who performed the genetic test carried a pathogenic variant in an LS-associated gene. Three MSI-high individuals had non-LS gene alterations, including BRCA1, BRCA2, and CDKN2A pathogenic variants, indicating the presence of non-LS-associated gene alterations among MSI-high patients.

CONCLUSION

Although MSI analysis is routinely performed in clinical practice, as many as 77% of MSI-high patients do not undergo LS genetic testing, despite international guidelines strongly recommending it. BRAF and MLH1 methylation analysis could shed light on the somatic origin of MSI in 42.50% of the MSI-high patients; however, MLH1 analysis is barely ever requested in clinical practice.

Focusing on colorectal cancer in young adults (Review)

Colorectal cancer (CRC) ranks as the third leading cause of cancer-related mortality worldwide. Recent years have witnessed an increase in the incidence of CRC among adults <50 years old on a global scale. The increased incidence is associated with several modifiable risk factors, including obesity, type II diabetes, physical inactivity and frequent antibiotic use. In younger individuals, haematochezia and abdominal pain are the most common symptoms, predominantly affecting the left-side colon. While certain cases of early-onset CRC (eoCRC) are associated with a genetic predisposition, the majority result from sporadic mutations in the genes APC, KRAS, BRAF and TP53, which trigger uncontrolled cell proliferation and tumour formation. Colorectal carcinogenesis involves three major pathways: The chromosomal instability (CIN), microsatellite instability and CpG island methylator phenotype pathways. Dysregulation of the CIN pathway accounts for 85% of sporadic cases of eoCRC. Notably, eoCRC exhibits a distinctive molecular profile, characterized by a decreased prevalence of BRAF mutations, an increased prevalence of KRAS mutations and LINE-1 hypomethylation, and involvement of the Microsatellite and Chromosomal Stable pathway. Prevention strategies for eoCRC primarily centre on lifestyle modifications and the development of screening programs targeting younger populations. Further exploration into the molecular mechanisms involved in the identification of novel risk factors associated with eoCRC is imperative. These efforts, in conjunction with the development of specific screening strategies, hold the potential to reduce morbidity and mortality in the future.

The Diagnostic Yield of Genetic Testing in Patients With Multiple Colorectal Adenomas: A Specialist Center Cohort Study

INTRODUCTION

Adenoma multiplicity is associated with increased colorectal cancer (CRC) risk. The utility of genetic testing in patients with multiple colorectal adenomas (MCRA) remains uncertain. We evaluated the diagnostic yield of mutations in polyposis- and CRC-associated genes in patients with MCRA.

METHODS

We performed a cross-sectional review of adult patients with 10-99 cumulative adenomas from the prospective database at the St Mark's Hospital Polyposis Registry and Family Cancer Clinic between 1999 and 2021. Genetic testing was performed for adenomatous polyposis-associated genes, hamartomatous polyposis-associated genes, and nonpolyposis colorectal cancer-associated genes. Clinicopathological outcomes were extracted for multiple logistic regression analysis.

RESULTS

Two hundred fifty-nine patients with MCRA (median age 61 [interquartile range 53-69] years) were identified. Sixty-six patients (25.5%) had a pathogenic variant or likely pathogenic variant, with APC and biallelic MUTYH mutations constituting the majority of identified pathogenic variant/likely pathogenic variants. Diagnostic yields were greater than 10% at any adenoma burden. In univariate analysis, higher adenoma burden and younger age were associated with higher yield (both P < 0.0001). In patients with MCRA with 10-19 adenomas without a relevant personal or family history of CRC, the diagnostic yield was nil. In multiple logistic regression analysis, higher adenoma burden, younger age, personal history of CRC, and first-degree familial history of CRC were associated with higher diagnostic yield.

DISCUSSION

Diagnostic yield of >10% at any adenoma burden supports current guidance for constitutional genetic testing in patients with MCRA, although the low yield in people older than 60 years with 10-19 adenomas suggests that a stratified approach might be appropriate.

Rare single-nucleotide variants of MLH1 and MSH2 genes in patients with Lynch syndrome

BACKGROUND

Approximately 5% of colorectal cancers (CRCs) are hereditary. Lynch syndrome (LS), also known as hereditary nonpolyposis colorectal cancer (HNPCC), is the most common form of recognized hereditary CRC. Although Iran, as a developing country, has a high incidence of CRC, the spectrum of variants has yet to be thoroughly investigated.

AIMS

This study aimed to investigate pathogenic and non-pathogenic variants in MLH1 and MSH2 genes in Iranian patients with suspected Lynch syndrome (sLS).

METHODS AND RESULTS

In the present study, 25 peripheral blood samples were collected from patients with sLS and high microsatellite instability (MSI-H). After DNA extraction, all samples underwent polymerase chain reaction and Sanger sequencing to identify the variants in the exons of MLH1 and MSH2 genes. The identified variants were interpreted using prediction tools, and were finally reported under ACMG guidelines. In our study population, 13 variants were found in the MLH1 gene and 8 in the MSH2 gene. Interestingly, 7 of the 13 MLH1 variants and 3 of the 8 MSH2 variants were novel, whereas the remaining variants were previously reported or available in databases. In addition, some patients with sLS did not have variants in the exons of the MLH1 and MSH2 genes. The variants detected in the MLH1 and MSH2 genes had specific characteristics regarding the number, area of occurrence, and their relationship with demographic and clinicopathologic features.

CONCLUSION

Overall, our results suggest that analysis of MLH1 and MSH2 genes alone is insufficient in the Iranian population, and more comprehensive tests are recommended for detecting LS.

Genetic predisposition to gastrointestinal polyposis: syndromes, tumour features, genetic testing, and clinical management

Gastrointestinal tract polyposis is characterised by the presence of multiple polyps, particularly in the colorectum, and encompasses both cancer predisposition genetic syndromes and non-syndromic clinical manifestations. The sources of the heterogeneity observed in polyposis syndromes relate to genetic cause, mode of inheritance, polyp burden and histological type, and spectrum and frequency of extracolonic manifestations. These features determine the clinical management of carriers, including strategies for cancer prevention and early detection, and oncological treatments. Despite substantial progress in identifying the genetic causes of polyposis, a large proportion of cases remain genetically unexplained. Although some of these cases might be due to lifestyle, environmental factors, or cancer treatments, it is likely that additional polyposis predisposition genes will be identified. This Review provides an overview of the known syndromes and genes, genetic testing, and clinical management of patients with polyposis, and recent advances and challenges in the field of gastrointestinal polyposis.

Epidemiology and early screening strategies for colorectal cancer in China

China ranks the first worldwide in the number of new colorectal cancer (CRC) cases and CRC-related deaths. The increasing incidence of early-onset CRC in recent years highlights the challenges related to CRC screening and prevention. High-quality colonoscopy is the universally used gold standard for CRC screening. Risk assessment combined with a two-step screening strategy based on colonoscopy and non-invasive examinations was proven to be highly effective. However, systematic use of well-established risk factors associated with CRC, beyond age, could better identify those who might harbor advanced colorectal neoplasia, improve the diagnostic yield of current screening modalities, and optimize the selection of individuals who might benefit most from preventive strategies. "Personalization" and "Standardization" are the future development directions of CRC screening, from the initiation of screening in those at high risk for CRC to follow-up after treatment, which are the key to ensure the screening efficiency.

Direct letters to relatives at risk of hereditary cancer-study protocol for a multi-center randomized controlled trial of healthcare-assisted versus family-mediated risk disclosure at Swedish cancer genetics clinics (DIRECT-study)

BACKGROUND

The results of germline genetic testing for hereditary cancer are of importance not only to the patients under investigation but also to their genetic at-risk relatives. Standard care is to encourage the proband (first family member under investigation) to pass on this risk information to the relatives. Previous research suggests that with family-mediated disclosure, only about a third of at-risk relatives contact health care to receive genetic counselling. In some studies, complementing family-mediated risk disclosure with healthcare-assisted risk disclosure almost doubles the uptake of genetic counselling in at-risk relatives. In this study, we evaluate healthcare-assisted direct letters to relatives at risk of hereditary cancer syndromes in a randomized controlled trial.

METHODS

Probands are recruited from Swedish outpatient cancer genetics clinics to this two-arm randomized controlled trial. The study recruits probands with either a pathogenic variant in a cancer susceptibility gene (BRCA1, BRCA2, PALB2, MLH1, MSH2, MSH6, PMS2) or probands with familial breast and colorectal cancer based on clinical and pedigree criteria. In both arms, probands receive standard care, i.e., are encouraged and supported to pass on information to relatives. In the intervention arm, the proband is also offered to have direct letters sent to the at-risk relatives. The primary outcome measure is the proportion of at-risk relatives contacting a Swedish cancer genetics clinic within 12 months of the proband receiving the test results.

DISCUSSION

This paper describes the protocol of a randomized controlled clinical trial evaluating a healthcare-assisted approach to risk disclosure by offering the probands to send direct letters to their at-risk relatives. The results of this study should be informative in the future development of risk disclosure practices in cancer genetics clinics.

TRIAL REGISTRATION

ClinicalTrials.gov. Identifier NCT04197856 (pre-trial registration on December 13, 2019). Also registered at the website "RCC Cancerstudier i Sverige" as study #86719.

Genotype-phenotype correlation for extracolonic aggressive phenotypes in patients with familial adenomatous polyposis

Familial adenomatous polyposis (FAP) patients develop various life-threatening extracolonic comorbidities that appear individually or within a family. This diversity can be explained by the localization of the adenomatous polyposis coli (APC) variant, but few reports provide definitive findings about genotype-phenotype correlations. Therefore, we investigated FAP patients and the association between the severe phenotypes and APC variants. Of 247 FAP patients, 126 patients from 85 families identified to have APC germline variant sites were extracted. These sites were divided into six groups (Regions A to F), and the frequency of severe comorbidities was compared among the patient phenotypes. Of the 126 patients, the proportions of patients with desmoid tumor stage ≥III, number of FGPs ≥1000, multiple gastric neoplasms, gastric neoplasm with high-grade dysplasia, and Spigelman stage ≥III were 3%, 16%, 21%, 12%, and 41%, respectively, while the corresponding rates were 30%, 50%, 70%, 50%, and 80% in patients with Region E (codons 1398-1580) variants. These latter rates were significantly higher than those for patients with variants in other regions. Moreover, the proportion of patients with all three indicators (desmoid tumor stage ≥III, number of FGPs ≥1000, and Spigelman stage ≥III) was 20% for those with variants in Region E and 0% for those with variants in other regions. Variants in Region E indicate aggressive phenotypes, and more intensive management is required.

Coordinated prospective follow-up of Lynch syndrome is able to detect the majority of incident cancers

BACKGROUND

Lynch syndrome is one of the most common genetic predispositions to many cancers, most of which do not have a consensus recommendation for screening.

AIMS

We studied in our region the value of a systematized and coordinated follow-up program for patients with Lynch syndrome on all organs at risk.

METHODS

A multicenter prospective cohort evaluation was performed, from January 2016 to June 2021.

RESULTS

One hundred and seventy-eight patients were prospectively included (104 women (58%), median age 44 years, range 35-56 years) with a median follow-up of 4 years (range 2.5-5 years), corresponding to a total of 652 patient-years. The overall cancer incidence rate was 13.80 per 1000 patient-years. Seven of nine cancers (78%) were detected during the follow-up program, with all cancers identified at an early stage. The detection rate of adenomas during colonoscopies was 24%.

CONCLUSION

These preliminary data suggest that coordinated prospective follow-up of Lynch syndrome is capable of detecting the majority of incident cancers, particularly for locations not covered by an international follow-up recommendation. However, these results need to be confirmed by larger-scale studies.

Superior rectal artery preservation to reduce anastomotic leak rates in familial adenomatous polyposis patients treated with total colectomy and ileorectal anastomosis

BACKGROUND

Total colectomy with ileorectal anastomosis (TC/IRA) is one of the prophylactic surgical options in patients with familial adenomatous polyposis (FAP). This study investigated the effectiveness of superior rectal artery (SRA) preservation during TC/IRA in reducing anastomotic leakage (AL).

METHODS

This retrospective study was based on prospectively collected data (01/2000 - 12/2022) at the National Cancer Institute, Milan, Italy. FAP patients undergoing TC/IRA were enrolled. A 1:1  propensity score matching (PSM) was performed. Associations between SRA preservation and complications were investigated using univariate and multivariate analysis.

RESULTS

The study population included 211 patients undergoing TC/IRA (Sex: 106 Male, 105 Female; Age: median 30 yrs, IQR: 20-48 yrs), 82 with SRA preservation (SRA group) and 129 without SRA preservation (controls). After PSM, 75 patients were considered for each group. SRA preservation was associated with fewer complications (OR 0.331, 95% CI 0.116; 0.942) in univariate logistic regression analysis. AL events were significantly fewer in the SRA group than in the control group (0 vs 12, p = 0.028). The SRA group had fewer overall surgical complication and pelvic sepsis rates (p = 0.020 and p = 0.028, respectively). Median operative time was significantly longer in the SRA group (340 min vs 240 min, p<0.001), and median hospital stay was significantly shorter (6 vs 7 days, p=0.017). Twenty-seven patients in the SRA group experienced intraoperative anastomotic bleeding, which was controlled endoscopically. Superimposable results were obtained analyzing the whole patient cohort.

CONCLUSIONS

SRA preservation can be considered an advantage in this patient population, despite adding a further technical step during surgery and thereby prolonging the operative time. Intraoperative endoscopic checking of possible anastomotic bleeding sites is recommended.

Proactive familial cancer risk assessment: a service development study in UK primary care

BACKGROUND

Family history assessment can identify individuals above population-risk for cancer to enable targeted Screening, Prevention, and Early Detection (SPED). Family History Questionnaire Service (FHQS) is a resource-efficient patient-facing online tool to facilitate this. In the UK, cancer risk assessment is usually only offered to concerned individuals proactively self-presenting to their GP, leading to inequity in accessing SPED in the community.

AIM

To improve access to community cancer genetic risk assessment and explore barriers to uptake.

DESIGN & SETTING

Service development project of a digital pathway using the FHQS for cancer risk assessment across four general practices within the clinical remit of the South West Thames Centre for Genomics (SWTCG).

METHOD

3100 individuals aged 38-50 years were invited to complete the FHQS through either text message or email. A random selection of 100 non-responders were contacted to determine barriers to uptake.

RESULTS

In total, n = 304/3100 (10%) registered for the FHQS. Responders were more likely to be British (63% vs 47%, P<0.001), speak English as their main language (92% vs 76%, P<0.001), and not require an interpreter (99.6% vs 94.9%, P = 0.001). Of 304 responders, 158 (52%) were automatically identified as at population-risk without full family history review. Of the remaining 146 responders, 52 (36%) required either additional screening referral (n = 23), genetics referral (n = 15), and/or advice to relatives (n = 18). Of 100 non-responders contacted, eight had incorrect contact details and 53 were contactable. Reasons for not responding included not receiving invitation details (n = 26), losing the invitation (n = 5), or forgetting (n = 4).

CONCLUSION

The FHQS can be used as part of a low-resource primary care pathway to identify individuals in the community above population-risk for cancer requiring action. This study highlighted barriers to uptake requiring consideration to maximise impact and minimise inequity.

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.

[Results of Endoscopic Screening and Therapy of the Duodenum in MUTYH-associated Polyposis]

MUTYH-associated polyposis (MAP) is a very rare autosomal recessive polyposis syndrome. It is caused by a homozygous or compound heterozygous germline mutation in the MUTYH gene. MAP is characterised by numerous colorectal adenomas; furthermore there is an increased risk for colorectal cancer (CRC). However, the phenotype can be highly variable; for example, affected individuals also have an increased risk of polyps of the upper gastrointestinal tract and development of duodenal carcinomas.This study included 15 patients with evidence of a pathogenic MUTYH variant, who were screened at the National Center for Hereditary Tumor Syndromes. Oesophagogastroduodenoscopy (EGD) results were prospectively recorded in a database from 2012 to 2023.At least one EGD (median 4, range 1-15) was performed in 15 patients, seven of whom carried a homozygous and 8 a compound heterozygous pathogenic MUTYH variant. The median surveillance period was 115 months (range, 3-215 months). The median age at baseline was 44 (range 17-65) years. A total of 72 EGDs were performed (median 4; range 1-15). Five patients had duodenal adenomas; histology showed tubular adenomas with low grade intraepithelial dysplasia (LGIEN) in all of these cases. The total number of duodenal adenomas detected was 48, and the median number was 3 (range, 1-37). Neither high grade intraepithelial neoplasia (HGIEN) nor duodenal cancer was detected during the surveillance period.Patients with MUTYH-associated polyposis should be managed in a multidisciplinary centre for hereditary tumour disease. Our cohort showed more patients with duodenal adenomas than in previously published data. However, no progression to HGIEN or duodenal carcinomas was observed as a result of the endoscopic therapy performed.

[Novel Treatment Concepts in Patients with Colorectal Carcinomas and High Microsatellite Instability]

Approximately 15% of patients with colorectal cancer show high microsatellite instability (MSI-high) in their tumour tissue. For one third of these patients, there is a hereditary cause for this finding - that leads to the diagnosis of Lynch Syndrome. In combination with clinical findings such as the Amsterdam or the revised Bethesda criteria, MSI-high status has been used as a tool in identifying patients at risk. Today, MSI-status has gained much more importance, due to its impact on treatment decisions. Patients with UICC II cancers should not receive adjuvant treatment. For patients with distant metastases and MSI-high status, immune checkpoint inhibitors can be given as first line therapy - with tremendous success. Novel data show a deep response for immune checkpoint antibodies in patients with locally advanced colon as well as rectal cancer in a neoadjuvant setting. Especially for patients with MSI-high rectal cancer, there might be a novel therapeutic regimen utilising immune checkpoint inhibitors without neoadjuvant radio-chemotherapy and even without surgery. This could lead to a relevant reduction in morbidity in this patient cohort. In conclusion, universal MSI-testing is essential for identifying patients at risk for Lynch syndrome and for optimal decision making in treatment planning.