Molecular Mechanisms of Alcohol-Induced Colorectal Carcinogenesis

The etiology of colorectal cancer (CRC) is complex. Approximately, 10% of individuals with CRC have predisposing germline mutations that lead to familial cancer syndromes, whereas most CRC patients have sporadic cancer resulting from a combination of environmental and genetic risk factors. It has become increasingly clear that chronic alcohol consumption is associated with the development of sporadic CRC; however, the exact mechanisms by which alcohol contributes to colorectal carcinogenesis are largely unknown. Several proposed mechanisms from studies in CRC models suggest that alcohol metabolites and/or enzymes associated with alcohol metabolism alter cellular redox balance, cause DNA damage, and epigenetic dysregulation. In addition, alcohol metabolites can cause a dysbiotic colorectal microbiome and intestinal permeability, resulting in bacterial translocation, inflammation, and immunosuppression. All of these effects can increase the risk of developing CRC. This review aims to outline some of the most significant and recent findings on the mechanisms of alcohol in colorectal carcinogenesis. We examine the effect of alcohol on the generation of reactive oxygen species, the development of genotoxic stress, modulation of one-carbon metabolism, disruption of the microbiome, and immunosuppression.

Leveraging Health Information Technology to Collect Family Cancer History: A Systematic Review and Meta-Analysis

PURPOSE Collection of family cancer histories (FCHs) can identify individuals at risk for familial cancer syndromes. The aim of this study is to evaluate the literature on existing strategies whereby providers use information technology to assemble FCH. METHODS A systematic search of online databases (Ovid MEDLINE, Cochrane, and Embase) between 1980 and 2020 was performed. Statistical heterogeneity was assessed through the chi-square test (ie, Cochrane Q test) and the inconsistency statistic (I2). A random-effects analysis was used to calculate the pooled proportions and means. RESULTS The comprehensive search produced 4,005 publications. Twenty-eight studies met inclusion criteria. Twenty-seven information technology tools were evaluated. Eighteen out of 28 studies were electronic surveys administered before visits (18, 64.3%). Five studies administered tablet surveys in offices (5, 17.8%). Four studies collected electronic survey via kiosk before visits (4, 14.3%), and one study used animated virtual counselor during visits (1, 3.6%). Among the studies that use an FCH tool, the pooled estimate of the overall completion rate was 86% (CI, 72% to 96%), 84% (CI, 65% to 97%) for electronic surveys before visits, 89% (CI, 0.74 to 0.98) for tablet surveys, and 85% (CI, 0.66 to 0.98) for surveys via kiosk. Mean time required for completion was 31.0 minutes (CI, 26.1 to 35.9), and the pooled estimate of proportions of participants referred to genetic testing was 12% (CI, 4% to 23%). CONCLUSION Our review found that electronic FCH collection can be completed successfully by patients in a time-efficient manner with high rates of satisfaction.

Young-Onset Carcinogenesis – The Potential Impact of Perinatal and Early Life Metabolic Influences on the Epigenome

The last decade has witnessed a significant rise in cancers in young adults. This spectrum of solid organ cancers occurring in individuals under the age of 40 years (some reports extending the age-group to <50 years) in whom aetiology of cancer cannot be traced back to pre-existing familial cancer syndromes, is referred to as termed young-, or early- onset cancers. The underlying causes for young-onset carcinogenesis have remained speculative. We recently proposed a hypothesis to explain the causation of this entity. We propose that the risk for young-onset cancer begins in the perinatal period as a result of the exposure of the foetus to stressors, including maternal malnutrition, smoking or alcohol, with the consequent epigenomic events triggered to help the foetus cope/adapt. Exposure to the same stressors, early in the life of that individual, facilitates a re-activation of these ‘responses designed to be protective’ but ultimately resulting in a loss of regulation at a metabolic and/or genetic level culminating in the evolution of the neoplastic process. In this manuscript, we will provide a rationale for this hypothesis and present evidence to further support it by clarifying the pathways involved, including elucidating a role for Acetyl-CoA and its effect on the epigenome. We present strategies and experimental models that can be used to test the hypothesis. We believe that a concerted effort by experts in different, but complementary fields, such as epidemiology, genetics, and epigenetics united towards the common goal of deciphering the underlying cause for young-onset cancers is the urgent need. Such efforts might serve to prove, or disprove, the presented hypothesis. However, the more important aim is to develop strategies to reverse the disturbing trend of the rise in young-onset cancers.

Utility of Discordant Mismatch Repair-Deficiency (MMR)/Microsatellite Instability (MSI) Testing in Screening Uterine Leiomyosarcoma Patient for Lynch/Other Familial Cancer Syndromes

Casestudy Lynch Syndrome (LS) is primarily linked to colorectal and endometrial cancers. Occasional sarcomas, including leiomyosarcoma, have been recognized within the spectrum of LS demonstrating mismatch repair-deficiency (MMR)/microsatellite instability (MSI) in this context. Results A 67-year-old female of bilineal Ashkenazi Jewish descent was recently diagnosed with uterine leiomyosarcoma in addition to metastatic papillary thyroid carcinoma at age 58. She met NCCN criteria for LS and BRCA1/2 (brother with renal cancer at age 64, father with colon cancer at age 60, paternal half-sister with rectal cancer at age 50 and maternal aunt with breast cancer). Studies have shown that immunohistochemistry (IHC) for MMR proteins and PCR-based MSI have comparable sensitivity and specificity with high concordance, but neither test alone is sufficient to capture all defective MMR tumors. Screening strategies vary depending on the level of clinical suspicion for LS. When high, a normal result by one method warrants testing via a second method or concurrent IHC plus PCR testing to minimize the impact of rare false normal results. Rarely, this strategy can yield discordant results, as in our case wherein MSI by PCR was stable (MSS) but IHC for MLH-1 and PMS-2 showed heterogeneous (patchy/focal) nuclear loss of protein expression. The latter is not always due to artefact but can correspond to MMR status differences within the tumor, requiring recognition to prevent false-positive/false-negative evaluations. Heterogenous MLH1 and/or PMS2 expression, may be suggestive of variable MLH1 methylation/second hit mutations, variable epitope expression or expression related to variable differentiation. Conclusion The clinical significance of this pattern was unclear in our patient whose initial genetic screen (including MLH1, PMS2, MSH2, MSH6, EPCAM) was negative. However, as studies have indicated that patients with indeterminate IHC findings can have MLH1 hypermethylation or germline mutations, she had justification to undergo extended genetic screening. A heterozygous pathogenic variant in BLM 2207_2212delinsTAGATTC (p.Tyr736Leufs*5) associated with autosomal recessive Bloom Syndrome (BS) was identified. Carriers of BS do not show symptoms of the disease, but they are at a greater than average risk of developing cancers.

The genetic and epigenetic landscape of early-onset colorectal cancer

Colorectal cancer (CRC) in individuals under the age of 50 is a problem that is increasing in USA and around the world. In this review, we discuss the degree to which early-onset (EO)CRC may be due to unsuspected Lynch syndrome or other inherited germline variants that predispose to cancer, describe the known somatic genetic alterations in EO tumors and discuss alterations in DNA methylation. Approximately 20% of EOCRCs can be attributed to identifiable germline mutations in genes that cause familial cancer syndromes. A variety of other genetic/epigenetic alterations have also been reported. We conclude that this is a heterogeneous problem, that requires a comprehensive analysis of genetic/epigenetic signatures to better understand EOCRC. Various subsets of EOCRCs must be analyzed individually for clues regarding the etiologies and possible specific therapies for this disease.

Lower gastrointestinal symptoms and symptoms-based triaging systems are poor predictors of clinical significant disease on colonoscopy

IntroductionLower gastrointestinal symptoms (LGS) are a common cause of referral to the gastroenterology service. International guidelines are available to prioritise referrals. Some studies have reported that symptoms alone are a poor marker of clinically significant disease (CSD) but symptoms remain the main way to prioritise referrals in routine clinical practice.Aims/backgroundTo correlate LGS with colonoscopy findings in an unselected patient cohort and to investigate whether using National Institute for Health and Care Excellence (NICE) guidelines improve risk stratification.MethodColonoscopy data over a 2-year period were obtained from our endoscopy database. Only patients with assessment of symptoms as their primary indication for colonoscopy were included. Patient records were retrospectively reviewed. Exclusion criteria: known inflammatory bowel disease (IBD), familial cancer syndromes, polyp and colorectal cancer (CRC) surveillance, and prior colonoscopy within 5 years. Demographics, symptoms and colonoscopy findings were recorded and analysed.Results1116 cases were reviewed; 493 (44%) males, age 54.3 years (16–91). CSD occurred in only 162 (14.5%); CRC 19 (1.7%), high-risk adenoma 40 (3.6%), inflammation 97 (8.7%) (IBD 65 (5.8%), microscopic colitis 9 (0.8%) and indeterminate-inflammation 23 (2%)), angiodysplasia 6 (0.5%). Diarrhoea gave the highest diagnostic yield for CSD of 5.3% (OR 3.15, 95% CI 2.2 to 4.7, p<0.001), followed by PR bleeding, 2.9% (OR 1.9, 95% CI 1.24 to 2.9, p=0.003). Weight loss gave the lowest diagnostic yield of 0.4%; (OR 0.79, 95% CI 0.28 to 2.24, p=0.65). 592 (53%) and 517 (46%) fitted the NICE guidelines for CRC and IBD, respectively. Using NICE positivity improved detection but overall yield remained low 3% vs 0.4% (OR 7.71, 95% CI 1.77 to 33.56, p=0.0064) for CRC, and 9% vs 2.8% (OR 3.5, 95% CI 1.99 to 6.17, p<0.0001) for IBD.ConclusionsThe overall prevalence of CSD in our unselected symptomatic patients is low (14.5%). A holistic approach including combining symptoms and demographics with novel tools including stool biomarkers and minimally invasive colonoscopy alternatives should be applied to avoid unnecessary colonoscopy.

Genetics

Clinical genetics is the medical specialty that deals with diagnosis and counselling of patients affected (or potentially affected) with disease that may have a genetic basis. These conditions include chromosomal abnormalities (e.g. Down’s syndrome/trisomy 21), single gene disorders (e.g. cystic fibrosis), familial cancer syndromes (e.g. hereditary non-polyposis colorectal cancer), and birth defects with a genetic component (e.g. cleft palate). The service is largely consultant led, supported by genetic counsellors in tertiary referral centres. Different inheritance patterns are described, autosomal dominant, autosomal recessive, X-linked, and mitochondrial, as well as the range of different genetic tests currently in clinical use (karyotype, microarray, gene panel, exome sequencing, and genome studies). The importance of empathetic communication, a detailed family history, and a multidisciplinary approach are emphasized.