Germ-line mutations in the exonuclease domains of the POLE and POLD1 genes are associated with an increased, but yet unquantified, risk of colorectal cancer (CRC).
We identified families with POLE or ...POLD1 variants by searching PubMed for relevant studies prior to October 2016 and by genotyping 669 population-based CRC cases diagnosed in patients under 60 years of age, from the Australasian Colorectal Cancer Family Registry. We estimated the age-specific cumulative risks (penetrance) using a modified segregation analysis.
We observed 67 CRCs (mean age at diagnosis = 50.2 (SD = 13.8) years) among 364 first- and second-degree relatives from 41 POLE families, and 6 CRCs (mean age at diagnosis = 39.7 (SD = 6.83) years) among 69 relatives from 9 POLD1 families. We estimated risks of CRC up to the age of 70 years (95% confidence interval) for males and females, respectively, to be 28% (95% CI, 10–42%) and 21% (95% CI, 7–33%) for POLE mutation carriers and 90% (95% CI, 33–99%) and 82% (95% CI, 26–99%) for POLD1 mutation carriers.
CRC risks for POLE mutation carriers are sufficiently high to warrant consideration of colonoscopy screening and implementation of management guidelines recommended for MSH6 mutation carriers in cases of Lynch syndrome. Refinement of estimates of CRC risk for POLD1 carriers is needed; however, clinical management recommendations could follow those made for POLE carriers.
BRAF mutations in colorectal cancer (CRC) are disproportionately observed in tumors exhibiting microsatellite instability (MSI) and are associated with other prognostic factors. The independent ...association between BRAF mutation status and CRC survival, however, remains unclear.
We evaluated the association between the BRAF c.1799T>A (p.V600E) mutation and survival in individuals with incident invasive CRC diagnosed between 1997 and 2007 in Western Washington State. Tumor specimens were tested for this BRAF mutation and MSI status. We used Cox regression to estimate HRs and 95% confidence intervals (CI) for the association between BRAF mutation status and disease-specific and overall survival. Stratified analyses were conducted by age, sex, tumor site, stage, and MSI status.
Among 1,980 cases tested, 12% were BRAF c.1799T>A (p.V600E) mutation-positive (n = 247). BRAF-mutated CRC was associated with poorer disease-specific survival adjusting for age, sex, time from diagnosis to enrollment, stage, and MSI status (HR, 1.43; 95% CI, 1.05-1.95). This association was limited to cases diagnosed at ages <50 (HR, 3.06; 95% CI, 1.70-5.52) and was not evident in cases with MSI-high tumors (HR, 0.94; 95% CI, 0.44-2.03). Associations with overall survival were similar.
Our results show that the prevalence of BRAF mutations in CRC differs by patient and tumor characteristics and suggest that the association between BRAF status and CRC survival may differ by some of these factors.
The presence of a BRAF c.1799T>A (p.V600E) mutation is associated with significantly poorer prognosis after CRC diagnosis among subgroups of patients.
BackgroundTumor-infiltrating lymphocytes (TILs), especially CD8+ TILs, can be used for predicting immunotherapy responsiveness and survival outcome. However, the evaluation of CD8+ TILs currently ...relies on histopathological methodology with high variability. We therefore aimed to develop a DNA methylation signature for CD8+ TILs (CD8+ MeTIL) that could evaluate immune response and prognosis in colorectal cancer (CRC).MethodsA CD8+ MeTIL signature score was constructed by using CD8+ T cell-specific differentially methylated positions (DMPs) that were identified from Illumina EPIC methylation arrays. Immune cells, colon epithelial cells, and two CRC cohorts (n=282 and 335) were used to develop a PCR-based assay for quantitative analysis of DNA methylation at single-base resolution (QASM) to determine CD8 + MeTIL signature score.ResultsThree CD8+ T cell-specific DMPs were identified to construct the CD8+ MeTIL signature score, which showed a dramatic discriminability between CD8+ T cells and other cells. The QASM assay we developed for CD8+ MeTIL markers could measure CD8+ TILs distributions in a fully quantitative, accurate, and simple manner. The CD8+ MeTIL score determined by QASM assay showed a strong association with histopathology-based CD8+ TIL counts and a gene expression-based immune marker. Furthermore, the low CD8+ MeTIL score (enriched CD8+ TILs) was associated with MSI-H tumors and predicted better survival in CRC cohorts.ConclusionsThis study developed a quantitative DNA methylation-based signature that was reliable to evaluate CD8+ TILs and prognosis in CRC. This approach has the potential to be a tool for investigations on CD8+ TILs and a biomarker for therapeutic approaches, including immunotherapy.
Parkinson's disease (PD) is a neurodegenerative disorder characterized by a combination of motor symptoms. We identified two functional single nucleotide polymorphisms in the glycogen synthase ...kinase‐3β gene (GSK3B). A promoter single nucleotide polymorphism (rs334558) is associated with transcriptional strength in vitro in which the T allele has greater activity. An intronic single nucleotide polymorphism (rs6438552) regulates selection of splice acceptor sites in vitro. The T allele is associated with altered splicing in lymphocytes and increased levels of GSK3B transcripts that lack exons 9 and 11 (GSKΔexon9+11). Increased levels of GSKΔexon9+11 correlated with enhanced phosphorylation of its substrate, Tau. In a comparison of PD and control brains, there was increased in frequency of T allele (rs6438552) and corresponding increase in GSKΔexon9+11 and Tau phosphorylation in PD brains. Conditional logistic regression indicated gene–gene interaction between T/T genotype of rs334558 and H1/H1 haplotype of microtubule‐associated protein Tau (MAPT) gene (p = 0.009). There was association between a haplotype (T alleles of both GSK3B polymorphisms) and disease risk after stratification by Tau haplotypes ((H1/H2+H2/H2 individuals: odds ratio, 1.64; p = 0.007; (H1/H1 individuals: odds ratio, 0.68; p < 0.001). Ours results suggest GSK3B polymorphisms alter transcription and splicing and interact with Tau haplotypes to modify disease risk in PD. Ann Neurol 2005;58:829–839
Abstract
Measures of biological age based on blood DNA methylation, referred to as age acceleration (AA), have been developed. We examined whether AA was associated with health risk factors and ...overall and cause-specific mortality. At baseline (1990–1994), blood samples were drawn from 2,818 participants in the Melbourne Collaborative Cohort Study (Melbourne, Victoria, Australia). DNA methylation was determined using the Infinium HumanMethylation450 BeadChip array (Illumina Inc., San Diego, California). Mixed-effects models were used to examine the association of AA with health risk factors. Cox models were used to assess the association of AA with mortality. A total of 831 deaths were observed during a median 10.7 years of follow-up. Associations of AA were observed with male sex, Greek nationality (country of birth), smoking, obesity, diabetes, lower education, and meat intake. AA measures were associated with increased mortality, and this was only partly accounted for by known determinants of health (hazard ratios were attenuated by 20%–40%). Weak evidence of heterogeneity in the association was observed by sex (P = 0.06) and cause of death (P = 0.07) but not by other factors. DNA-methylation-based AA measures are associated with several major health risk factors, but these do not fully explain the association between AA and mortality. Future research should investigate what genetic and environmental factors determine AA.
Lifestyle-related phenotypes have been shown to be heritable and associated with DNA methylation. We aimed to investigate whether genetic predisposition to tobacco smoking, alcohol consumption, and ...higher body mass index (BMI) moderates the effect of these phenotypes on blood DNA methylation. We calculated polygenic scores (PGS) to quantify genetic predisposition to these phenotypes using training (N = 7,431) and validation (N = 4,307) samples. Using paired genetic-methylation data (N = 4,307), gene-environment interactions (i.e., PGS × lifestyle) were assessed using linear mixed-effects models with outcomes: 1) methylation at sites found to be strongly associated with smoking (1,061 CpGs), alcohol consumption (459 CpGs), and BMI (85 CpGs) and 2) two epigenetic ageing measures, PhenoAge and GrimAge. In the validation sample, PGS explained ~1.4% (P = 1 × 10
−14
), ~0.6% (P = 2 × 10
−7
), and ~8.7% (P = 7 × 10
−87
) of variance in smoking initiation, alcohol consumption, and BMI, respectively. Nominally significant interaction effects (P < 0.05) were found at 61, 14, and 7 CpGs for smoking, alcohol consumption, and BMI, respectively. There was strong evidence that all lifestyle-related phenotypes were positively associated with PhenoAge and GrimAge, except for alcohol consumption with PhenoAge. There was weak evidence that the association of smoking with GrimAge was attenuated in participants genetically predisposed to smoking (interaction term: −0.022, standard error SE = 0.012, P = 0.058) and that the association of alcohol consumption with PhenoAge was attenuated in those genetically predisposed to drink alcohol (interaction term: −0.030, SE = 0.015, P = 0.041). In conclusion, genetic susceptibility to unhealthy lifestyles did not strongly modify the association between observed lifestyle behaviour and blood DNA methylation. Potential associations were observed for epigenetic ageing measures, which should be replicated in additional studies.
Lynch syndrome is the most common form of hereditary colorectal carcinoma. However, establishing the diagnosis of Lynch syndrome is challenging, and ancillary studies that distinguish between ...sporadic DNA mismatch repair (MMR) protein deficiency and Lynch syndrome are needed, particularly when germline mutation studies are inconclusive. The aim of this study was to determine if MMR protein-deficient non-neoplastic intestinal crypts can help distinguish between patients with and without Lynch syndrome. We evaluated the expression of MMR proteins in non-neoplastic intestinal mucosa obtained from colorectal surgical resection specimens from patients with Lynch syndrome-associated colorectal carcinoma (n = 52) and patients with colorectal carcinoma without evidence of Lynch syndrome (n = 70), including sporadic MMR protein-deficient colorectal carcinoma (n = 30), MMR protein proficient colorectal carcinoma (n = 30), and “Lynch-like” syndrome (n = 10). MMR protein-deficient non-neoplastic colonic crypts were identified in 19 of 122 (16%) patients. MMR protein-deficient colonic crypts were identified in 18 of 52 (35%) patients with Lynch syndrome compared to only 1 of 70 (1%) patients without Lynch syndrome (p < 0.001). This one patient had “Lynch-like” syndrome and harbored two MSH2-deficient non-neoplastic colonic crypts. MMR protein-deficient non-neoplastic colonic crypts were not identified in patients with sporadic MMR protein-deficient or MMR protein proficient colorectal carcinoma. Our findings suggest that MMR protein-deficient colonic crypts are a novel indicator of Lynch syndrome, and evaluation for MMR protein-deficient crypts may be a helpful addition to Lynch syndrome diagnostics.
The influence of lifestyle factors on survival following a diagnosis of colorectal cancer (CRC) is not well established. We examined associations between lifestyle factors measured before diagnosis ...and CRC survival. The Melbourne Collaborative Cohort Study collected data on alcohol intake, cigarette smoking and physical activity, and body measurements at baseline (1990–1994) and wave 2 (2003–2007). We included participants diagnosed to 31 August 2015 with incident stages I–III CRC within 10‐years post exposure assessment. Information on tumor characteristics and vital status was obtained. Tumor DNA was tested for microsatellite instability (MSI) and somatic mutations in oncogenes BRAF (V600E) and KRAS. We estimated hazard ratios (HRs) for associations between lifestyle factors and overall and CRC‐specific mortality using Cox regression. Of 724 eligible CRC cases, 339 died (170 from CRC) during follow‐up (average 9.0 years). Exercise (non‐occupational/leisure‐time) was associated with higher CRC‐specific survival for stage II (HR = 0.25, 95% CI: 0.10–0.60) but not stages I/III disease (p for interaction = 0.01), and possibly for colon and KRAS wild‐type tumors. Waist circumference was inversely associated with CRC‐specific survival (HR = 1.25 per 10 cm increment, 95% CI: 1.08–1.44), independent of stage, anatomic site and tumor molecular status. Cigarette smoking was associated with lower overall survival, with suggestive evidence of worse survival for BRAF mutated CRC, but not with CRC‐specific survival. Alcohol intake was not associated with survival. Survival did not differ by MSI status. We have identified pre‐diagnostic predictors of survival following CRC that may have clinical and public health relevance.
What's new?
While survival following colorectal cancer (CRC) is improving, it remains unclear whether increasing survival is linked to specific health or lifestyle factors that were present before or after CRC diagnosis. In our study, based on data from the Melbourne Collaborative Cohort Study (MCCS), exercise prior to diagnosis was associated with higher CRC‐specific survival specifically for stage II patients. Waist circumference, by contrast, was associated with reduced CRC‐specific survival, while cigarette smoking was associated with lower overall survival. Cigarette smoking was also weakly linked to decreased survival in BRAF‐mutated CRC. No associations were detected between CRC survival and alcohol intake.
The Australian National Bowel Cancer Screening Programme (NBCSP) was introduced in 2006. When fully implemented, the programme will invite people aged 50 to 74 to complete an immunochemical faecal ...occult blood test (iFOBT) every 2 years.
To investigate colorectal cancer (CRC) screening occurring outside of the NBCSP, we classified participants (n = 2,480) in the Australasian Colorectal Cancer Family Registry (ACCFR) into 3 risk categories (average, moderately increased, and potentially high) based on CRC family history and assessed their screening practices according to national guidelines. We developed a microsimulation to compare hypothetical screening scenarios (70% and 100% uptake) to current participation levels (baseline) and evaluated clinical outcomes and cost for each risk category. The 2 main limitations of this study are as follows: first, the fact that our cost-effectiveness analysis was performed from a third-party payer perspective, which does not include indirect costs and results in overestimated cost-effectiveness ratios, and second, that our natural history model of CRC does not include polyp sojourn time, which determines the rate of cancerous transformation. Screening uptake was low across all family history risk categories (64%-56% reported no screening). For participants at average risk, 18% reported overscreening, while 37% of those in the highest risk categories screened according to guidelines. Higher screening levels would substantially reduce CRC mortality across all risk categories (95 to 305 fewer deaths per 100,000 persons in the 70% scenario versus baseline). For those at average risk, a fully implemented NBCSP represented the most cost-effective approach to prevent CRC deaths (AUS$13,000-16,000 per quality-adjusted life year QALY). For those at moderately increased risk, higher adherence to recommended screening was also highly cost-effective (AUS$19,000-24,000 per QALY).
Investing in public health strategies to increase adherence to appropriate CRC screening will save lives and deliver high value for money.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
•Genomic testing can predict risks of disease for all in the population.•We explored decision-making & attitudes about genomic testing in general practice.•Attitudes towards the genomic test were ...predominantly positive.•Many indifferent attitudes showed that the test did not pose significant concern.•This study will inform GPs’ future counselling for patients considering genomic testing.
A genomic test to predict personal risk of colorectal cancer (CRC) that targets screening and could be feasibly implemented in primary care. We explored informed decision-making and attitudes towards genomic testing in this setting.
A CRC genomic test was offered to 150 general practice patients with brief discussion of its implications. We measured informed choice about the test, consisting knowledge, attitudes and test uptake. Sixteen purposively-sampled participants were interviewed.
Of 150, 142 (95%) completed the informed choice measure and of 27 invited, 16 (59%) completed an interview. 73% made an informed choice about the test. Interviews revealed that participants with inadequate knowledge on the informed choice scale still understood the gist of the test. While positive attitudes were most prevalent, some had concerns, and many were indifferent to the test. Positive attitudes included: that risk information could facilitate risk reduction; negative attitudes included: that risk results could cause worry and be used for insurance discrimination; indifferent attitudes included: that the test seemed benign and it was easy to do.
Our study adds to the evidence that genomic tests for CRC risk do not pose significant concern to patients in community settings.
As genomic tests become more prevalent, this study’s findings can be used to facilitate informed decision-making and ensure equitable access.
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