Search

BACKGROUND: MLH1 epimutation is characterised by constitutional monoallelic MLH1 promoter hypermethylation, which can cause colorectal cancer (CRC). Tumour molecular profiles of MLH1 epimutation CRCs were used to classify germline MLH1 promoter variants of uncertain significance and MLH1 methylated early-onset CRCs (EOCRCs). Genome-wide DNA methylation and somatic mutational profiles of tumours from two germline MLH1: c.-11C > T and one MLH1: c.-[28A > G; 7C > T] carriers and three MLH1 methylated EOCRCs (< 45 years) were compared with 38 reference CRCs. Methylation-sensitive droplet digital PCR (ddPCR) was used to detect mosaic MLH1 methylation in blood, normal mucosa and buccal DNA. RESULTS: Genome-wide methylation-based Consensus Clustering identified four clusters where the tumour methylation profiles of germline MLH1: c.-11C > T carriers and MLH1 methylated EOCRCs clustered with the constitutional MLH1 epimutation CRCs but not with the sporadic MLH1 methylated CRCs. Furthermore, monoallelic MLH1 methylation and APC promoter hypermethylation in tumour were observed in both MLH1 epimutation and germline MLH1: c.-11C > T carriers and MLH1 methylated EOCRCs. Mosaic constitutional MLH1 methylation in MLH1: c.-11C > T carriers and 1 of 3 MLH1 methylated EOCRCs was identified by methylation-sensitive ddPCR. CONCLUSIONS: Mosaic MLH1 epimutation underlies the CRC aetiology in MLH1: c.-11C > T germline carriers and a subset of MLH1 methylated EOCRCs. Tumour profiling and ultra-sensitive ddPCR methylation testing can be used to identify mosaic MLH1 epimutation carriers.

Routine screening of tumors for DNA mismatch repair (MMR) deficiency (dMMR) in colorectal (CRC), endometrial (EC) and sebaceous skin (SST) tumors leads to a significant proportion of unresolved cases classified as suspected Lynch syndrome (SLS). SLS cases (n = 135) were recruited from Family Cancer Clinics across Australia and New Zealand. Targeted panel sequencing was performed on tumor (n = 137; 80×CRCs, 33×ECs and 24xSSTs) and matched blood-derived DNA to assess for microsatellite instability status, tumor mutation burden, COSMIC tumor mutational signatures and to identify germline and somatic MMR gene variants. MMR immunohistochemistry (IHC) and MLH1 promoter methylation were repeated. In total, 86.9% of the 137 SLS tumors could be resolved into established subtypes. For 22.6% of these resolved SLS cases, primary MLH1 epimutations (2.2%) as well as previously undetected germline MMR pathogenic variants (1.5%), tumor MLH1 methylation (13.1%) or false positive dMMR IHC (5.8%) results were identified. Double somatic MMR gene mutations were the major cause of dMMR identified across each tumor type (73.9% of resolved cases, 64.2% overall, 70% of CRC, 45.5% of ECs and 70.8% of SSTs). The unresolved SLS tumors (13.1%) comprised tumors with only a single somatic (7.3%) or no somatic (5.8%) MMR gene mutations. A tumor-focused testing approach reclassified 86.9% of SLS into Lynch syndrome, sporadic dMMR or MMR-proficient cases. These findings support the incorporation of tumor sequencing and alternate MLH1 methylation assays into clinical diagnostics to reduce the number of SLS patients and provide more appropriate surveillance and screening recommendations.

OBJECTIVE: The unknown aetiology of Serrated Polyposis Syndrome (SPS) impedes risk prediction and prevention. We investigated risk factors for SPS, overall and stratified by World Health Organization (WHO)2010 clinical criteria and by colorectal cancer (CRC). METHOD: A retrospective case-control study involving a cross-sectional analysis from 350 unrelated individuals with SPS from the Genetics of Colonic Polyposis Study and 714 controls from the Australasian Colorectal Cancer Family Registry. Univariate and multivariate logistic regression modelling was used to determine the association between risk factors and SPS and risk factors associated with CRC in SPS. RESULTS: Female biological sex (odds ratio (OR) = 4.54; 95%Confidence interval (CI) = 2.77-7.45), increasing body mass index (BMI) at age 20 years (OR = 1.09; 95%CI = 1.04-1.13), hormone replacement therapy (OR = 0.44; 95%CI = 0.20.98), and increasing weekly folate intake (OR = 0.82; 95%CI = 0.75-0.90) were associated with SPS by multivariate analysis. Increasing weekly calcium intake (OR = 0.79; 95%CI = 0.64-0.97) and smoking > 10 cigarettes daily (OR = 0.45; 95%CI = 0.23-0.86) were associated with WHO criterion I only. The consumption of 1-100 g of alcohol per week (OR = 0.39; 95%CI = 0.18-0.83) was associated with WHO criterion III only. Smoking 1-5 cigarettes daily (OR = 2.35; 95%CI = 1.09-5.05), weekly non-steroidal anti-inflammatory drug (NSAIDs) intake (OR = 0.88; 95%CI = 0.78-0.99), and increased height (OR = 1.09; 95% = 1.05-1.13), were associated with SPS fulfilling both WHO criteria I and III. Moreover, weekly NSAIDs intake (OR = 0.81; 95%CI = 0.67-0.98) was associated with a reduced likelihood of CRC in SPS. CONCLUSION: We identified novel risk and potential protective factors associated with SPS, some specific for certain WHO2010 criteria. Weekly use of NSAIDs may reduce the risk of CRC in people with SPS.

BACKGROUND: The aim of this study was to determine the proportions and predictors of first-degree relatives (FDRs) of colorectal cancer (CRC) patients (i) ever receiving any CRC testing and (ii) receiving CRC screening in accordance with CRC screening guidelines. METHODS: Colorectal cancer patients and their FDRs were recruited through the population-based Victorian Cancer Registry, Victoria, Australia. Seven hundred and seven FDRs completed telephone interviews. Of these, 405 FDRs were deemed asymptomatic and eligible for analysis. RESULTS: Sixty-nine percent of FDRs had ever received any CRC testing. First-degree relatives of older age, those with private health insurance, siblings and FDRs who had ever been asked about family history of CRC by a doctor were significantly more likely than their counterparts to have ever received CRC testing. Twenty-five percent of FDRs "at or slightly above average risk" were adherent to CRC screening guidelines. For this group, adherence to guideline-recommended screening was significantly more likely to occur for male FDRs and those with a higher level of education. For persons at "moderately increased risk" and "potentially high risk", 47% and 49% respectively adhered to CRC screening guidelines. For this group, guideline-recommended screening was significantly more likely to occur for FDRs who were living in metropolitan areas, siblings, those married or partnered and those ever asked about family history of CRC. CONCLUSIONS: A significant level of non-compliance with screening guidelines was evident among FDRs. Improved CRC screening in accordance with guidelines and effective systematic interventions to increase screening rates among population groups experiencing inequality are needed. TRIAL REGISTRATION: Australian and New Zealand Clinical Trial Registry: ACTRN12609000628246.

BACKGROUND: Participation rates in colorectal cancer screening (CRC) are low. Relatively little is known about screening uptake across varying levels of risk and across population groups. The purpose of the current study was to identify factors associated with (i) ever receiving colorectal cancer (CRC) testing; (ii) risk-appropriate CRC screening in accordance with guidelines; and (iii) recent colonoscopy screening. METHODS: 1592 at-risk persons (aged 56-88 years) were randomly selected from the Hunter Community Study (HCS), Australia. Participants self-reported family history of CRC was used to quantify risk in accordance with national screening guidelines. RESULTS: 1117 participants returned a questionnaire; 760 respondents were eligible for screening and analysis. Ever receiving CRC testing was significantly more likely for persons: aged 65-74 years; who had discussed with a doctor their family history of CRC or had ever received screening advice. For respondents "at or slightly above average risk", guideline-appropriate screening was significantly more likely for persons: aged 65-74 years; with higher household income; and who had ever received screening advice. For respondents at "moderately or potentially high risk", guideline-appropriate screening was significantly more likely for persons: with private health insurance and who had discussed their family history of CRC with a doctor. Colonoscopy screening was significantly more likely for persons: who had ever smoked; discussed their family history of CRC with a doctor; or had ever received screening advice. CONCLUSIONS: The level of risk-appropriate screening varied across populations groups. Interventions that target population groups less likely to engage in CRC screening are pivotal for decreasing screening inequalities.

BACKGROUND: Little data exists on the factors associated with health care seeking behaviour for primary symptoms of colorectal cancer (CRC). This study aimed to identify individual, provider and psychosocial factors associated with (i) ever seeking medical advice and (ii) seeking early medical advice for primary symptoms of colorectal cancer (CRC). METHODS: 1592 persons aged 56-88 years randomly selected from the Hunter Community Study (HCS) were sent a questionnaire. RESULTS: Males and those who had received screening advice from a doctor were at significantly higher odds of ever seeking medical advice for rectal bleeding. Persons who had private health coverage, consulted a doctor because the 'symptom was serious', or who did not wait to consult a doctor for another reason were at significantly higher odds of seeking early medical advice (< 2 weeks). For change in bowel habit, persons with lower income, within the healthy weight range, or who had discussed their family history of CRC irrespective of whether informed of 'increased risk' were at significantly higher odds of ever seeking medical advice. Persons frequenting their GP less often and seeing their doctor because the symptom persisted were at significantly higher odds of seeking early medical advice (< 2 weeks). CONCLUSIONS: The seriousness of symptoms, importance of early detection, and prompt consultation must be articulated in health messages to at-risk persons. This study identified modifiable factors, both individual and provider-related to consultation behaviour. Effective health promotion efforts must heed these factors and target sub-groups less likely to seek early medical advice.

BACKGROUND: Family history is a common risk factor for colorectal cancer (CRC), yet it is often underused to guide risk assessment and the provision of risk-appropriate CRC screening recommendation. The aim of this study was to identify from a patient perspective health care providers' current practice relating to: (i) assessment of family history of CRC; (ii) notification of "increased risk" to patients at "moderately/potentially high" familial risk; and (iii) recommendation that patients undertake CRC screening. METHODS: 1592 persons aged 56-88 years randomly selected from the Hunter Community Study (HCS), New South Wales, Australia were mailed a questionnaire. 1117 participants (70%) returned a questionnaire. RESULTS: Thirty eight percent of respondents reported ever being asked about their family history of CRC. Ever discussing family history of CRC with a health care provider was significantly more likely to occur for persons with a higher level of education, who had ever received screening advice and with a lower physical component summary score. Fifty one percent of persons at "moderately/potentially high risk" were notified of their "increased risk" of developing CRC. Thirty one percent of persons across each level of risk had ever received CRC screening advice from a health care provider. Screening advice provision was significantly more likely to occur for persons who had ever discussed their family history of CRC with a health care provider and who were at "moderately/potentially high risk". CONCLUSIONS: Effective interventions that integrate both the assessment and notification of familial risk of CRC to the wider population are needed. Systematic and cost-effective mechanisms that facilitate family history collection, risk assessment and provision of screening advice within the primary health care setting are required.

BACKGROUND: Familial adenomatous polyposis (FAP) is a hereditary disorder characterized by polyposis along the gastrointestinal tract. Information on adenoma status below the duodenum has previously been restricted due to its inaccessibility in vivo. Capsule Endoscopy (CE) may provide a useful adjunct in screening for polyposis in the small bowel in FAP patients. This study aims to evaluate the effectiveness of CE in the assessment of patients with FAP, compared to other imaging modalities for the detection of small bowel polyps. METHOD: 20 consecutive patients with previously diagnosed FAP and duodenal polyps, presenting for routine surveillance of polyps at The Royal Melbourne Hospital were recruited. Each fasted patient initially underwent a magnetic resonance image (MRI) of the abdomen, and a barium small bowel follow-through study. Capsule Endoscopy was performed four weeks later on the fasted patient. An upper gastrointestinal side-viewing endoscopy was done one (1) to two (2) weeks after this. Endoscopists and investigators were blinded to results of other investigations and patient history. RESULTS: Within the stomach, upper gastrointestinal endoscopy found more polyps than other forms of imaging. SBFT and MRI generally performed poorly, identifying fewer polyps than both upper gastrointestinal and capsule endoscopy. CE was the only form of imaging that identified polyps in all segments of the small bowel as well as the only form of imaging able to provide multiple findings outside the stomach/duodenum. CONCLUSION: CE provides important information on possible polyp development distal to the duodenum, which may lead to surgical intervention. The place of CE as an adjunct in surveillance of FAP for a specific subset needs consideration and confirmation in replication studies. TRIAL REGISTRATION: Australian New Zealand Clinical Trials Registry ACTRN12608000616370.