Search

Objective: Leptin (LEP) is an obesity-associated adipokine associated with tumor cell growth. We examined the relevance of genetic variants of LEP and leptin receptor ( LEPR ) to colorectal cancer (CRC) survival by using data from the Newfoundland Familial Colorectal Cancer Study., Methods: A total of 532 patients newly diagnosed with CRC between 1997 and 2003 were followed up until April 2010. Data on their demographics and lifestyles were collected via questionnaires. Genotyping of blood samples was performed with the Illumina Human Omni-Quad Bead chip. Multivariable Cox models were used to assess the relationships of 35 tag single-nucleotide polymorphisms (SNPs) in LEP and LEPR with overall survival (OS), disease-free survival (DFS), and CRC-specific survival., Results: At the gene level, LEP was associated with DFS ( P = 0.017), and LEPR was associated with both DFS ( P = 0.021) and CRC-specific survival ( P = 0.013) in patients with CRC. In single-SNP analysis, LEP rs11763517, LEPR rs9436301, and LEPR rs7602 were associated with DFS after adjustment for multiple testing. The LEPR haplotypes G-C-T (rs7534511-rs9436301-rs1887285) and A-A-G (rs7602-rs970467-rs9436748) were associated with prolonged OS among patients with CRC overall (G-C-T: HR, 0.63; 95% CI, 0.43-0.93; A-A-G: HR, 0.59; 95% CI, 0.38-0.91) and those diagnosed with colon cancer (G-C-T: HR, 0.54; 95% CI, 0.34-0.86; A-A-G: HR, 0.49; 95% CI, 0.29-0.83). Similar results were observed for DFS. Moreover, significant interactions were found among LEPR rs7602 (A vs. G), LEPR rs1171278 (T vs . C), red meat intake, and BMI status: the associations between these variants and prolonged DFS were limited to patients with below-median red meat consumption and body mass index (BMI) < 25 kg/m 2 ., Conclusions: Polymorphic variations in the LEP and LEPR genes were associated with survival of patients after CRC diagnosis. The LEP / LEPR -CRC survival association was modified by participants' red meat intake and BMI., Competing Interests: No potential conflicts of interest are disclosed., (Copyright © 2023 Cancer Biology & Medicine.)

Background: Paradoxically epidemiological data illustrate a negative relationship between dietary folate intake and colorectal cancer (CRC) risk. The occurrence and progression of CRC may be influenced by variants in some key enzyme coding genes in the folate metabolic pathway. We investigated the correlation between genetic variants in methionine synthase reductase ( MTRR ) and methylenetetrahydrofolate reductase ( MTHFR ) and CRC survival., Methods: This study used data collected from the Newfoundland Familial Colorectal Cancer Study. A total of 532 patients diagnosed with CRC for the first time from 1999 to 2003 were enrolled, and their mortality were tracked until April 2010. DNA samples were genotyped by Illumina's integrated quantum 1 million chip. Cox models were established to assess 33 tag single-nucleotide polymorphisms in MTRR and MTHFR in relation to overall survival (OS), disease-free survival (DFS) and CRC-specific survival., Results: The MTRR and MTHFR genes were associated with DFS and CRC-specific survival in CRC patients at the gene level. After multiple comparison adjustment, MTRR rs1801394 A (vs. G) allele was associated with increased DFS ( p = 0.024), while MTHRT rs3737966 (G vs. A), rs4846049 (T vs. G), rs1476413 (A vs. G), rs1801131 (C vs. A), rs12121543 (A vs. C), rs1801133 (C vs. T), rs4846052 (T vs. C), rs2066471 (A vs. G) and rs7533315 (T vs. C) were related to worse CRC-specific survival. Additionally, significant interactions were seen among pre-diagnostic alcohol consumption with MTRR rs1801394, rs3776467, rs326124, rs162040, and rs3776455, with superior OS associated with those protective variant alleles limited to patients with alcohol consumption under the median. The MTHFR rs3737966 (G vs. A) allele seemed to be detrimental to CRC survival only among subjects with fruit intake below the median., Conclusions: Polymorphic variants in MTRR and MTHFR genes that code for key enzymes for folate metabolism may be associated with survival in patients with CRC. The gene-CRC outcome association seems modulated by alcohol drinking and fruit intake.

Background: The incidence of colorectal cancer (CRC) among individuals aged younger than 50 years has been increasing. As screening guidelines lower the recommended age of screening initiation, concerns including the burden on screening capacity and costs have been recognized, suggesting that an individualized approach may be warranted. We developed risk prediction models for early-onset CRC that incorporate an environmental risk score (ERS), including 16 lifestyle and environmental factors, and a polygenic risk score (PRS) of 141 variants., Methods: Relying on risk score weights for ERS and PRS derived from studies of CRC at all ages, we evaluated risks for early-onset CRC in 3486 cases and 3890 controls aged younger than 50 years. Relative and absolute risks for early-onset CRC were assessed according to values of the ERS and PRS. The discriminatory performance of these scores was estimated using the covariate-adjusted area under the receiver operating characteristic curve., Results: Increasing values of ERS and PRS were associated with increasing relative risks for early-onset CRC (odds ratio per SD of ERS = 1.14, 95% confidence interval [CI] = 1.08 to 1.20; odds ratio per SD of PRS = 1.59, 95% CI = 1.51 to 1.68), both contributing to case-control discrimination (area under the curve = 0.631, 95% CI = 0.615 to 0.647). Based on absolute risks, we can expect 26 excess cases per 10 000 men and 21 per 10 000 women among those scoring at the 90th percentile for both risk scores., Conclusions: Personal risk scores have the potential to identify individuals at differential relative and absolute risk for early-onset CRC. Improved discrimination may aid in targeted CRC screening of younger, high-risk individuals, potentially improving outcomes., (© The Author(s) 2022. Published by Oxford University Press. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Protective associations of fruits, vegetables, and fiber intake with colorectal cancer risk have been shown in many, but not all epidemiologic studies. One possible reason for study heterogeneity is that dietary factors may have distinct effects by colorectal cancer molecular subtypes. Here, we investigate the association of fruit, vegetables, and fiber intake with four well-established colorectal cancer molecular subtypes separately and in combination. Nine observational studies including 9,592 cases with molecular subtypes for microsatellite instability (MSI), CpG island methylator phenotype (CIMP), and somatic mutations in BRAF and KRAS genes, and 7,869 controls were analyzed. Both case-only logistic regression analyses and polytomous logistic regression analyses (with one control set and multiple case groups) were used. Higher fruit intake was associated with a trend toward decreased risk of BRAF -mutated tumors [OR 4th vs. 1st quartile = 0.82 (95% confidence interval, 0.65-1.04)] but not BRAF -wildtype tumors [1.09 (0.97-1.22); P difference as shown in case-only analysis = 0.02]. This difference was observed in case-control studies and not in cohort studies. Compared with controls, higher fiber intake showed negative association with colorectal cancer risk for cases with microsatellite stable/MSI-low, CIMP-negative, BRAF -wildtype, and KRAS -wildtype tumors ( P trend range from 0.03 to 3.4e-03), which is consistent with the traditional adenoma-colorectal cancer pathway. These negative associations were stronger compared with MSI-high, CIMP-positive, BRAF -mutated, or KRAS -mutated tumors, but the differences were not statistically significant. These inverse associations for fruit and fiber intake may explain, in part, inconsistent findings between fruit or fiber intake and colorectal cancer risk that have previously been reported. SIGNIFICANCE: These analyses by colorectal cancer molecular subtypes potentially explain the inconsistent findings between dietary fruit or fiber intake and overall colorectal cancer risk that have previously been reported., (©2020 American Association for Cancer Research.)

Background: Bilirubin, a byproduct of hemoglobin breakdown and purported anti-oxidant, is thought to be cancer preventive. We conducted complementary serological and Mendelian randomization (MR) analyses to investigate whether alterations in circulating levels of bilirubin are associated with risk of colorectal cancer (CRC). We decided a priori to perform analyses separately in men and women based on suggestive evidence that associations may differ by sex., Methods: In a case-control study nested in the European Prospective Investigation into Cancer and Nutrition (EPIC), pre-diagnostic unconjugated bilirubin (UCB, the main component of total bilirubin) concentrations were measured by high-performance liquid chromatography in plasma samples of 1386 CRC cases and their individually matched controls. Additionally, 115 single-nucleotide polymorphisms (SNPs) robustly associated (P < 5 × 10 -8 ) with circulating total bilirubin were instrumented in a 2-sample MR to test for a potential causal effect of bilirubin on CRC risk in 52,775 CRC cases and 45,940 matched controls in the Genetics and Epidemiology of Colorectal Cancer Consortium (GECCO), the Colon Cancer Family Registry (CCFR), and the Colorectal Transdisciplinary (CORECT) study., Results: The associations between circulating UCB levels and CRC risk differed by sex (P heterogeneity  = 0.008). Among men, higher levels of UCB were positively associated with CRC risk (odds ratio [OR] = 1.19, 95% confidence interval [CI] = 1.04-1.36; per 1-SD increment of log-UCB). In women, an inverse association was observed (OR = 0.86 (0.76-0.97)). In the MR analysis of the main UGT1A1 SNP (rs6431625), genetically predicted higher levels of total bilirubin were associated with a 7% increase in CRC risk in men (OR = 1.07 (1.02-1.12); P = 0.006; per 1-SD increment of total bilirubin), while there was no association in women (OR = 1.01 (0.96-1.06); P = 0.73). Raised bilirubin levels, predicted by instrumental variables excluding rs6431625, were suggestive of an inverse association with CRC in men, but not in women. These differences by sex did not reach formal statistical significance (P heterogeneity  ≥ 0.2)., Conclusions: Additional insight into the relationship between circulating bilirubin and CRC is needed in order to conclude on a potential causal role of bilirubin in CRC development.

Background & Aims: Early-onset colorectal cancer (CRC, in persons younger than 50 years old) is increasing in incidence; yet, in the absence of a family history of CRC, this population lacks harmonized recommendations for prevention. We aimed to determine whether a polygenic risk score (PRS) developed from 95 CRC-associated common genetic risk variants was associated with risk for early-onset CRC., Methods: We studied risk for CRC associated with a weighted PRS in 12,197 participants younger than 50 years old vs 95,865 participants 50 years or older. PRS was calculated based on single nucleotide polymorphisms associated with CRC in a large-scale genome-wide association study as of January 2019. Participants were pooled from 3 large consortia that provided clinical and genotyping data: the Colon Cancer Family Registry, the Colorectal Transdisciplinary Study, and the Genetics and Epidemiology of Colorectal Cancer Consortium and were all of genetically defined European descent. Findings were replicated in an independent cohort of 72,573 participants., Results: Overall associations with CRC per standard deviation of PRS were significant for early-onset cancer, and were stronger compared with late-onset cancer (P for interaction = .01); when we compared the highest PRS quartile with the lowest, risk increased 3.7-fold for early-onset CRC (95% CI 3.28-4.24) vs 2.9-fold for late-onset CRC (95% CI 2.80-3.04). This association was strongest for participants without a first-degree family history of CRC (P for interaction = 5.61 × 10 -5 ). When we compared the highest with the lowest quartiles in this group, risk increased 4.3-fold for early-onset CRC (95% CI 3.61-5.01) vs 2.9-fold for late-onset CRC (95% CI 2.70-3.00). Sensitivity analyses were consistent with these findings., Conclusions: In an analysis of associations with CRC per standard deviation of PRS, we found the cumulative burden of CRC-associated common genetic variants to associate with early-onset cancer, and to be more strongly associated with early-onset than late-onset cancer, particularly in the absence of CRC family history. Analyses of PRS, along with environmental and lifestyle risk factors, might identify younger individuals who would benefit from preventive measures., (Copyright © 2020 AGA Institute. Published by Elsevier Inc. All rights reserved.)

Alcohol consumption is an established risk factor for colorectal cancer (CRC). However, while studies have consistently reported elevated risk of CRC among heavy drinkers, associations at moderate levels of alcohol consumption are less clear. We conducted a combined analysis of 16 studies of CRC to examine the shape of the alcohol-CRC association, investigate potential effect modifiers of the association, and examine differential effects of alcohol consumption by cancer anatomic site and stage. We collected information on alcohol consumption for 14,276 CRC cases and 15,802 controls from 5 case-control and 11 nested case-control studies of CRC. We compared adjusted logistic regression models with linear and restricted cubic splines to select a model that best fit the association between alcohol consumption and CRC. Study-specific results were pooled using fixed-effects meta-analysis. Compared to non-/occasional drinking (≤1 g/day), light/moderate drinking (up to 2 drinks/day) was associated with a decreased risk of CRC (odds ratio [OR]: 0.92, 95% confidence interval [CI]: 0.88-0.98, p = 0.005), heavy drinking (2-3 drinks/day) was not significantly associated with CRC risk (OR: 1.11, 95% CI: 0.99-1.24, p = 0.08) and very heavy drinking (more than 3 drinks/day) was associated with a significant increased risk (OR: 1.25, 95% CI: 1.11-1.40, p < 0.001). We observed no evidence of interactions with lifestyle risk factors or of differences by cancer site or stage. These results provide further evidence that there is a J-shaped association between alcohol consumption and CRC risk. This overall pattern was not significantly modified by other CRC risk factors and there was no effect heterogeneity by tumor site or stage., (Published 2019. This article is a U.S. Government work and is in the public domain in the USA.)

To further dissect the genetic architecture of colorectal cancer (CRC), we performed whole-genome sequencing of 1,439 cases and 720 controls, imputed discovered sequence variants and Haplotype Reference Consortium panel variants into genome-wide association study data, and tested for association in 34,869 cases and 29,051 controls. Findings were followed up in an additional 23,262 cases and 38,296 controls. We discovered a strongly protective 0.3% frequency variant signal at CHD1. In a combined meta-analysis of 125,478 individuals, we identified 40 new independent signals at P < 5 × 10 -8 , bringing the number of known independent signals for CRC to ~100. New signals implicate lower-frequency variants, Krüppel-like factors, Hedgehog signaling, Hippo-YAP signaling, long noncoding RNAs and somatic drivers, and support a role for immune function. Heritability analyses suggest that CRC risk is highly polygenic, and larger, more comprehensive studies enabling rare variant analysis will improve understanding of biology underlying this risk and influence personalized screening strategies and drug development.

Background: Dietary patterns are commonly used in epidemiological research, yet there have been few studies assessing if and how research results may vary across dietary patterns. This study aimed to estimate the risk of mortality/recurrence/metastasis using different dietary patterns and comparison amongst the patterns., Methods: Dietary patterns were identified by Cluster Analysis (CA), Principal Component Analysis (PCA), Alternate Mediterranean Diet score (altMED), Recommended Food Score (RFS) and Dietary Inflammatory Index (DII) scores using a 169-item food frequency questionnaire. Five hundred thirty-two colorectal cancer patients diagnosed between 1999 and 2003 in Newfoundland were followed-up until 2010. Overall Mortality (OM) and combined Mortality, Recurrence or Metastasis (cMRM) were identified. Comparisons were made with adjusted Cox proportional Hazards Ratios (HRs), correlation coefficients and the distributions of individuals in defined clusters by quartiles of factor and index scores., Results: One hundred and seventy cases died from all causes and 29 had a cancer recurrence/metastasis during follow-up. Processed meats as classified by PCA (HR 1.82; 95% confidence interval (CI) 1.07-3.09), clusters characterized by meat and dairy products (HR 2.19; 95% CI 1.03-4.67) and total grains, sugar, soft drinks (HR 1.95; 95% CI 1.13-3.37) were associated with a higher risk of cMRM. Poor adherence to AltMED increased the risk of all-cause OM (HR 1.62; 95% CI 1.04-2.56). Prudent vegetable, high sugar pattern, RFS and DII had no significant association with both OM and cMRM., Conclusion: Estimation of OM and cMRM varied across dietary patterns which is attributed to the differences in the foundation of each pattern.

Background: The rs2282679 A>C polymorphism in the vitamin D binding protein gene is associated with lower circulating levels of vitamin D. We investigated associations of this SNP with colorectal cancer (CRC) risk and survival and whether the associations vary by dietary vitamin D intake and tumor molecular phenotype., Methods: A population-based case-control study identified 637 incident CRC cases (including 489 participants with follow-up data on mortality end-points) and 489 matched controls. Germline DNA samples were genotyped with the Illumina Omni-Quad 1 Million chip in cases and the Affymetrix Axiom® myDesign™ Array in controls. Logistic regression examined the association between the rs2282679 polymorphism and CRC risk with inclusion of potential confounders. Kaplan-Meier curves and multivariable Cox models assessed the polymorphism relative to overall survival (OS) and disease-free survival (DFS)., Results: The rs2282679 polymorphism was not associated with overall CRC risk; there was evidence, however, of effect modification by total vitamin D intake (P interaction  = 0.019). Survival analyses showed that the C allele was correlated with poor DFS (per-allele HR, 1.36; 95%CI, 1.05-1.77). The association of rs2282679 on DFS was limited to BRAF wild-type tumors (HR, 1.58; 95%CI, 1.12-2.23). For OS, the C allele was associated with higher all-cause mortality among patients with higher levels of dietary vitamin D (HR, 2.11; 95%CI, 1.29-3.74), calcium (HR, 1.93; 95%CI, 1.08-3.46), milk (HR, 2.36; 95%CI, 1.26-4.44), and total dairy product intakes (HR, 2.03; 95%CI, 1.11-3.72)., Conclusion: The rs2282679 SNP was not associated with overall CRC risk, but may be associated with survival after cancer diagnosis. The association of this SNP on survival among CRC patients may differ according to dietary vitamin D and calcium intakes and according to tumor BRAF mutation status.

Background: Metastasis is a major cause of mortality in cancer. Identifying prognostic factors that distinguish patients who will experience metastasis in the short-term and those that will be free of metastasis in the long-term is of particular interest in current medical research. The objective of this study was to examine if select genetic polymorphisms can differentiate colorectal cancer patients based on timing and long-term risk of metastasis., Methods: The patient cohort consisted of 402 stage I-III colorectal cancer patients with microsatellite instability (MSI)-low (MSI-L) or microsatellite stable (MSS) tumors. We applied multivariable mixture cure model, which is the proper model when there is a substantial group of patients who remain free of metastasis in the long-term, to 26 polymorphisms. Time-dependent receiver operator characteristic (ROC) curve analysis was performed to determine the change in discriminatory accuracy of the models when the significant SNPs were included., Results: After adjusting for significant baseline characteristics, two polymorphisms were significantly associated with time-to-metastasis: TT and TC genotypes of the XRCC3 Thr241Met (p = 0.042) and the 3R/3R genotype of TYMS 5'-UTR variable number tandem repeat (VNTR) (p = 0.009) were associated with decreased time-to-metastasis. ROC curves showed that the discriminatory accuracy of the model is increased slightly when these polymorphisms were added to the significant baseline characteristics., Conclusions: Our results indicate XRCC3 Thr241Met and TYMS 5'-UTR VNTR polymorphisms are associated with time-to-metastasis, and may have potential biological roles in expediting the metastatic process. Once replicated, these associations could contribute to the development of precision medicine for colorectal cancer patients.

Objective: Chronic inflammation is implicated in causing cancer. Diet plays an important role in regulating chronic inflammation by altering circulating levels of inflammatory biomarkers. Effect of single food or nutrient on cancer often is inconclusive; perhaps due to dietary interactions and multicolinearity. The aim of this study was to determine prediagnostic inflammatory potential of overall diet in relation to risk for colorectal cancer (CRC)., Methods: In all, 547 patients with CRC from Newfoundland Familial Colorectal Cancer Registry and 685 controls from the general population were identified. Data on sociodemographic, medical history, lifestyle, and a 169-item food frequency questionnaire were collected retrospectively from both groups. Energy-adjusted Dietary Inflammatory Index (DII) score was calculated and used as both categorical and continuous variables for analysis. Odds ratio was estimated using multivariable logistic regression after adjusting potential confounders. A linear test for trend was performed using the median value in each quartile., Results: Overall energy-adjusted mean DII score was -0.81 (range -5.19 to 6.93). Cases (-0.73 ± 1.5) had slightly higher DII scores than controls (-0.89 ± 1.6; P = 0.04). After adjusting the potential confounders, a statistically significant association was found between DII score and CRC risk. Using DII as a continuous variable (odds ratio [OR] continuous 1.10, 95% confidence interval [CI] 1.01-1.20) and categorical variable (OR quartile 1 versus 4 1.65, 95% CI 1.13-2.42; P trend  = 0.02)., Conclusion: Our findings indicate that proinflammatory diets are associated with an increased risk for CRC in the Newfoundland population., (Copyright © 2017 Elsevier Inc. All rights reserved.)

As Newfoundland has the highest rate of familial colorectal cancer (CRC) in the world, we started a population-based clinic to provide colonoscopic and Lynch syndrome (LS) screening recommendations to families of CRC patients based on family risk. Of 1091 incident patients 51% provided a family history. Seventy-two percent of families were at low or intermediate-low risk of CRC and colonoscopic screening recommendations were provided by letter. Twenty-eight percent were at high and intermediate-high risk and were referred to the genetic counsellor, but only 30% (N = 48) were interviewed by study end. Colonoscopy was recommended more frequently than every 5 years in 35% of families. Lower family risk was associated with older age of proband but the frequency of screening colonoscopy recommendations varied across all age groups, driven by variability in family history. Twenty-four percent had a high MMR predict score for a Lynch syndrome mutation, and 23% fulfilled the Provincial Program criteria for LS screening. A population-based approach in the provision of colonoscopic screening recommendations to families at risk of CRC was limited by the relatively low response rate. A family history first approach to the identification of LS families was inefficient., (© 2016 The Authors. Clinical Genetics published by John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Background: Aberrant Wnt signaling activation occurs commonly in colorectal carcinogenesis, leading to upregulation of many target genes. APC (adenomatous polyposis coli) is an important component of the β-catenin destruction complex, which regulates Wnt signaling, and is often mutated in colorectal cancer (CRC). In addition to mutational events, epigenetic changes arise frequently in CRC, specifically, promoter hypermethylation which silences tumor suppressor genes. APC and the Wnt signaling target gene ITF2 (immunoglobulin transcription factor 2) incur hypermethylation in various cancers, however, methylation-dependent regulation of these genes in CRC has not been studied in large, well-characterized patient cohorts. The microsatellite instability (MSI) subtype of CRC, featuring DNA mismatch repair deficiency and often promoter hypermethylation of MutL homolog 1 (MLH1), has a favorable outcome and is characterized by different chemotherapeutic responses than microsatellite stable (MSS) tumors. Other epigenetic events distinguishing these subtypes have not yet been fully elucidated., Methods: Here, we quantify promoter methylation of ITF2 and APC by MethyLight in two case-case studies nested in population-based CRC cohorts from the Ontario Familial Colorectal Cancer Registry (n = 330) and the Newfoundland Familial Colorectal Cancer Registry (n = 102) comparing MSI status groups., Results: ITF2 and APC methylation are significantly associated with tumor versus normal state (both P < 1.0 × 10(-6)). ITF2 is methylated in 45.8% of MSI cases and 26.9% of MSS cases and is significantly associated with MSI in Ontario (P = 0.002) and Newfoundland (P = 0.005) as well as the MSI-associated feature of MLH1 promoter hypermethylation (P = 6.72 × 10(-4)). APC methylation, although tumor-specific, does not show a significant association with tumor subtype, age, gender, or stage, indicating it is a general tumor-specific CRC biomarker., Conclusions: This study demonstrates, for the first time, MSI-associated ITF2 methylation, and further reveals the subtype-specific epigenetic events modulating Wnt signaling in CRC.

Several N-nitroso compounds (NOC) have been shown to be carcinogenic in a variety of laboratory animals, but evidence of their carcinogenicity in humans is lacking. We aimed to examine the association between NOC intake and colorectal cancer (CRC) risk and possible effect modification by vitamins C and E and protein in a large case-control study carried out in Newfoundland and Labrador and Ontario, Canada. A total of 1760 case patients with pathologically confirmed adenocarcinoma and 2481 population controls were asked to complete a self-administered FFQ to evaluate their dietary intakes 1 year before diagnosis (for cases) or interview (for controls). Adjusted OR and 95 % CI were calculated across the quintiles of NOC (measured by N-nitrosodimethylamine (NDMA)) intake and relevant food items using unconditional logistic regression. NDMA intake was found to be associated with a higher risk of CRC (highest v. lowest quintiles: OR 1·42, 95 % CI 1·03, 1·96; P for trend = 0·005), specifically for rectal carcinoma (OR 1·61, 95 % CI 1·11, 2·35; P for trend = 0·01). CRC risk also increased with the consumption of NDMA-containing meats when the highest tertile was compared with the lowest tertile (OR 1·47, 95 % CI 1·03, 2·10; P for trend = 0·20). There was evidence of effect modification between dietary vitamin E and NDMA. Individuals with high NDMA and low vitamin E intakes had a significantly increased risk than those with both low NDMA and low vitamin E intakes (OR 3·01, 95 % CI 1·43, 6·51; P for interaction = 0·017). The present results support the hypothesis that NOC intake may be positively associated with CRC risk in humans. Vitamin E, which inhibits nitrosation, could modify the effect of NDMA on CRC risk.

Background: Smoking is a risk factor for incident colorectal cancer (CRC); however, it is unclear about its influence on survival after CRC diagnosis., Methods: A cohort of 706 CRC patients diagnosed from 1999 to 2003 in Newfoundland and Labrador, Canada, was followed for mortality and recurrence until April 2010. Smoking and other relevant data were collected by questionnaire after cancer diagnosis, using a referent period of '2 years before diagnosis' to capture pre-diagnosis information. Molecular analyses of microsatellite instability (MSI) status and BRAF V600E mutation status were performed in tumour tissue using standard techniques. Multivariate hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated with Cox proportional hazards regression, controlling for major prognostic factors., Results: Compared with never smokers, all-cause mortality (overall survival, OS) was higher for current (HR: 1.78; 95% CI: 1.04-3.06), but not for former (HR: 1.06; 95% CI: 0.71-1.59) smokers. The associations of cigarette smoking with the study outcomes were higher among patients with ≥40 pack-years of smoking (OS: HR: 1.72; 95% CI: 1.03-2.85; disease-free survival (DFS: HR: 1.99; 95% CI: 1.25-3.19), those who smoked ≥30 cigarettes per day (DFS: HR: 1.80; 95% CI: 1.22-2.67), and those with microsatellite stable (MSS) or MSI-low tumours (OS: HR: 1.38; 95% CI: 1.04-1.82 and DFS: HR: 1.32; 95% CI: 1.01-1.72). Potential heterogeneity was noted for sex (DFS HR: 1.68 for men and 1.01 for women: P for heterogeneity=0.04), and age at diagnosis (OS: HR: 1.11 for patients aged <60 and 1.69 for patients aged ≥60: P for heterogeneity=0.03)., Conclusions: Pre-diagnosis cigarette smoking is associated with worsened prognosis among patients with CRC.

A recent report detailed the occurrence of both somatic and constitutional variants in the GALNT12 gene, located at 9q22.33, in some colorectal cancer (CRC) patients. In this study, we investigate the occurrence of inherited deleterious variants in GALNT12 in 118 families referred to a cancer genetics clinic. We discovered two deleterious variants (c.907G>A (p.Asp303Asn); c.1187A>G (p.Tyr396Cys)) in 4/118 probands. The variants, which were not found in 149 control individuals (P = 0.0376), cosegregate with CRC and/or adenomatous polyps in other family members. The probability by chance that cosegregation of c.907G>A with CRC and/or adenomatous polyps occurred, in the two pedigrees combined, was 1.56%. Although this study does not provide irrefutable evidence that GALNT12 variants are highly penetrant alleles that predispose to CRC in the majority of unexplained hereditary CRC families, it does provide additional evidence to support an important role of these variants in a proportion of this considerable high-risk group., (© 2012 Wiley Periodicals, Inc.)

Background: Diet is regarded as one of the most important environmental factors associated with colorectal cancer (CRC) risk. A recent report comprehensively concluded that total energy intake does not have a simple relationship with CRC risk, and that the data were inconsistent for carbohydrate, cholesterol and protein. The objective of this study was to identify the associations of CRC risk with dietary intakes of total energy, protein, fat, carbohydrate, fiber, and alcohol using data from a large case-control study conducted in Newfoundland and Labrador (NL) and Ontario (ON), Canada., Methods: Incident colorectal cancer cases (n = 1760) were identified from population-based cancer registries in the provinces of ON (1997-2000) and NL (1999-2003). Controls (n = 2481) were a random sample of residents in each province, aged 20-74 years. Family history questionnaire (FHQ), personal history questionnaire (PHQ), and food frequency questionnaire (FFQ) were used to collect study data. Logistic regression was used to evaluate the association of intakes of total energy, macronutrients and alcohol with CRC risk., Results: Total energy intake was associated with higher risk of CRC (OR: 1.56; 95% CI: 1.21-2.01, p-trend = 0.02, 5th versus 1st quintile), whereas inverse associations emerged for intakes of protein (OR: 0.85, 95%CI: 0.69-1.00, p-trend = 0.06, 5th versus 1st quintile), carbohydrate (OR: 0.81, 95%CI: 0.63-1.00, p-trend = 0.05, 5th versus 1st quintile) and total dietary fiber (OR: 0.84, 95% CI:0.67-0.99, p-trend = 0.04, 5th versus 1st quintile). Total fat, alcohol, saturated fatty acids, monounsaturated fatty acids, polyunsaturated fatty acids, and cholesterol were not associated with CRC risk., Conclusion: This study provides further evidence that high energy intake may increase risk of incident CRC, whereas diets high in protein, fiber, and carbohydrate may reduce the risk of the disease.

Background: While substantive epidemiological literature suggests that alcohol drinking and obesity are potential risk factors of colorectal cancer (CRC), the possible interaction between the two has not been adequately explored. We used a case-control study to examine if alcohol drinking is associated with an increased risk of CRC and if such risk differs in people with and without obesity., Methods: Newly diagnosed CRC cases were identified between 1999 and 2003 in Newfoundland and Labrador (NL). Cases were frequency-matched by age and sex with controls selected using random digit dialing. Cases (702) and controls (717) completed self-administered questionnaires assessing health and lifestyle variables. Estimates of alcohol intake included types of beverage, years of drinking, and average number of alcohol drinks per day. Odds ratios were estimated to investigate the associations of alcohol independently and when stratified by obesity status on the risk of CRC., Results: Among obese participants (BMI ≥ 30), alcohol was associated with higher risk of CRC (OR: 2.2; 95% CI: 1.2-4.0) relative to the non-alcohol category. Among obese individuals, 3 or more different types of drinks were associated with a 3.4-fold higher risk of CRC relative to non-drinkers. The risk of CRC also increased with drinking years and drinks daily among obese participants. However, no increased risk was observed in people without obesity., Conclusion: The effect of alcohol of drinking on CRC seems to be modified by obesity.

Aim: The impact of micronutrient intake and colorectal cancer (CRC) risk is poorly understood. The objective of this study was to evaluate the associations of selected micronutrients with risk of incident CRC in study participants from Newfoundland, Labrador (NL) and Ontario (ON), Canada., Materials and Methods: We conducted a population-based study among 1760 case participants and 2481 age- and sex-matched control participants. Information on diet and other lifestyle factors were measured using a food frequency questionnaire and a personal history questionnaire. Odds ratios (OR) and 95% confidence intervals (CI) were calculated using unconditional logistic regression, controlling for covariables., Results: Highest compared to lowest quartile intakes of certain micronutrients were associated with lower risk of CRC, including: calcium (from food and supplements (FS), OR=0.59; 95% CI=0.45-0.77, and from food only (FO): OR=0.76, 95% CI=0.59-0.97), vitamin C (FS:OR=0.67; 95%CI:0.51-0.88), vitamin D (FS: OR=0.73; 95% CI: 0.57-0.94, FO: OR=0.79, 95% CI=0.62-1.00), riboflavin (FS: OR=0.61; 95% CI=0.47-0.78, and folate (FS: OR=0.72; 95% CI=0.56-0.92). Higher risk of CRC was observed for iron intake (highest versus lowest quintiles: OR=1.34, 95% CI=1.01-1.78)., Conclusion: This study presents evidence that dietary intake of calcium, vitamin D, vitamin C, riboflavin and folate are associated with a lower risk of incident CRC and that dietary intake of iron may be associated with a higher risk of the disease.

Colorectal cancer is the second leading cause of cancer death in developed countries. Genome-wide association studies (GWAS) have successfully identified novel susceptibility loci for colorectal cancer. To follow up on these findings, and try to identify novel colorectal cancer susceptibility loci, we present results for GWAS of colorectal cancer (2,906 cases, 3,416 controls) that have not previously published main associations. Specifically, we calculated odds ratios and 95% confidence intervals using log-additive models for each study. In order to improve our power to detect novel colorectal cancer susceptibility loci, we performed a meta-analysis combining the results across studies. We selected the most statistically significant single nucleotide polymorphisms (SNPs) for replication using ten independent studies (8,161 cases and 9,101 controls). We again used a meta-analysis to summarize results for the replication studies alone, and for a combined analysis of GWAS and replication studies. We measured ten SNPs previously identified in colorectal cancer susceptibility loci and found eight to be associated with colorectal cancer (p value range 0.02 to 1.8 × 10(-8)). When we excluded studies that have previously published on these SNPs, five SNPs remained significant at p < 0.05 in the combined analysis. No novel susceptibility loci were significant in the replication study after adjustment for multiple testing, and none reached genome-wide significance from a combined analysis of GWAS and replication. We observed marginally significant evidence for a second independent SNP in the BMP2 region at chromosomal location 20p12 (rs4813802; replication p value 0.03; combined p value 7.3 × 10(-5)). In a region on 5p33.15, which includes the coding regions of the TERT-CLPTM1L genes and has been identified in GWAS to be associated with susceptibility to at least seven other cancers, we observed a marginally significant association with rs2853668 (replication p value 0.03; combined p value 1.9 × 10(-4)). Our study suggests a complex nature of the contribution of common genetic variants to risk for colorectal cancer.

Diet and lifestyle influence colorectal cancer (CRC) risk but the molecular events that mediate these effects are poorly characterized. Several dietary and lifestyle factors can modulate DNA methylation suggesting that they may influence CRC risk through epigenetic regulation of cancer-related genes. The Wnt regulatory genes DKK1 and Wnt5a are important contributors to colonic carcinogenesis and are often silenced by promoter hypermethylation in CRC; however, the dietary contributions to these events have not been explored. To investigate the link between dietary/lifestyle factors and epigenetic regulation of these Wnt signaling genes, we assessed promoter methylation of these genes in a large cohort of Canadian CRC patients from Ontario (n = 549) and Newfoundland (n = 443) and examined associations to dietary/lifestyle factors implicated in CRC risk and/or DNA methylation including intake of vitamins, fats, cholesterol, fiber, and alcohol as well as body mass index (BMI), and smoking status. Several factors were associated with methylation status including alcohol intake, BMI, and cigarette smoking. Most significantly, however, dietary vitamin D intake was strongly negatively associated with DKK1 methylation in Newfoundland (P = 0.001) and a similar trend was observed in Ontario. These results suggest that vitamin D and other dietary/lifestyle factors may alter CRC risk by mediating extracellular Wnt inhibition.

Background: Previous epidemiological studies have been suggestive but inconclusive in demonstrating inverse associations of calcium, vitamin D, dairy product intakes with risk of colorectal cancer (CRC). We conducted a large population-based comparison of such associations in Newfoundland and Labrador (NL) and Ontario (ON)., Methods: A case control study design was used. Colorectal cancer cases were new CRC patients aged 20-74 years. Controls were a sex and age-group matched random sample of the population in each province. 1760 cases and 2481 controls from NL and ON were analyzed. Information on dietary intake and lifestyle was collected using self-administered food frequency and personal history questionnaires., Results: Controls reported higher mean daily intakes of total calcium and total vitamin D than cases in both provinces. In ON, significant reduced CRC risk was associated with intakes of total calcium (OR of highest vs. lowest quintiles was 0.57, 95% CI 0.42-0.77, p(trend) = 0.03), total vitamin D (OR = 0.73, 95% CI 0.54-1.00), dietary calcium (OR = 0.76, 95% CI 0.60-0.97), dietary vitamin D (OR = 0.77, 95% CI 0.61-0.99), total dairy products and milk (OR = 0.78, 95% CI 0.60-1.00), calcium-containing supplements use (OR = 0.76). In NL, the inverse associations of calcium, vitamin D with CRC risk were most pronounced among calcium- or vitamin D-containing supplement users (OR = 0.67, 0.68, respectively)., Conclusions: Results of this study add to the evidence that total calcium, dietary calcium, total vitamin D, dietary vitamin D, calcium- or vitamin D-containing supplement use may reduce the risk of CRC. The inverse associations of CRC risk with intakes of total dairy products and milk may be largely due to calcium and vitamin D.

Background: In colorectal cancer (CRC), tumour microsatellite instability (MSI) status and CpG island methylator phenotype (CIMP) status are indicators of patient outcome, but the molecular events that give rise to these outcomes remain largely unknown. Wnt5a is a critical regulator of non-canonical Wnt activity and promoter hypermethylation of this gene has emerging prognostic roles in CRC; however the frequency and prognostic significance of this epigenetic event have not been explored in the context of colorectal tumour subtype. Consequently, we investigated the frequency and prognostic significance of Wnt5a methylation in a large cohort of MSI-stratified CRCs., Methods: Methylation was quantified in a large cohort of 1232 colorectal carcinomas from two clinically distinct populations from Canada. Associations were examined between methylation status and clinicopathlogical features, including tumour MSI status, BRAF V600E mutation, and patient survival., Results: In Ontario, Wnt5a methylation was strongly associated with MSI tumours after adjustment for age, sex, and tumour location (odds ratio (OR)=4.2, 95% confidence interval (CI)=2.4-7.4, P<10(-6)) and with BRAF V600E mutation, a marker of CIMP (OR=12.3, 95% CI=6.9-21.7, P<10(-17)), but was not associated with patient survival. Concordant results were obtained in Newfoundland., Conclusion: Methylation of Wnt5a is associated with distinct tumour subtypes, strengthening the evidence of an epigenetic-mediated Wnt bias in CRC.

Aberrant activation of canonical Wnt signaling is a hallmark event in colorectal carcinogenesis. The Dickkopf-1 (DKK1) and Secreted Frizzled Related Protein 1 (SFRP1) genes encode extracellular inhibitors of Wnt signaling that are frequently silenced by promoter hypermethylation in colorectal cancer (CRC). These methylation events have been identified as prognostic markers of patient outcome and tumor subtype in several cancers but similar roles in CRC have not been comprehensively examined. In CRC, the microsatellite instability (MSI) subtype associates with favorable disease outcome but the molecular events that are responsible remain poorly understood. Consequently, we quantified promoter methylation status of the Wnt antagonist genes DKK1 and SFRP1 in a large population-based cohort of CRCs from Ontario (n = 549) and Newfoundland (n = 696) stratified by MSI status. We examined the association between methylation status and clinicopathological features including tumor MSI status and patient survival. DKK1 and SFRP1 were methylated in 13 and 95% of CRCs, respectively. In Ontario, DKK1 methylation was strongly associated with MSI tumors after adjustment for age, sex and tumor location [odds ratio (OR) = 13.7, 95% confidence interval (CI) = 7.8-24.2, P < 0.001]. Conversely, SFRP1 methylation was inversely associated with MSI tumors after these adjustments (OR = 0.3, 95% CI = 0.1-0.9, P = 0.009). Similar results were obtained in Newfoundland. There were no independent associations with recurrence-free survival. This is the first large study to identify associations between Wnt antagonist promoter hypermethylation and CRC MSI subtype. These events provide insight into subtype-specific epigenetic mediation of Wnt signaling in CRC.

Background: We previously identified an association between a mismatch repair gene, MLH1, promoter SNP (rs1800734) and microsatellite unstable (MSI-H) colorectal cancers (CRCs) in two samples. The current study expanded on this finding as we explored the genetic basis of DNA methylation in this region of chromosome 3. We hypothesized that specific polymorphisms in the MLH1 gene region predispose it to DNA methylation, resulting in the loss of MLH1 gene expression, mismatch-repair function, and consequently to genome-wide microsatellite instability., Methodology/principal Findings: We first tested our hypothesis in one sample from Ontario (901 cases, 1,097 controls) and replicated major findings in two additional samples from Newfoundland and Labrador (479 cases, 336 controls) and from Seattle (591 cases, 629 controls). Logistic regression was used to test for association between SNPs in the region of MLH1 and CRC, MSI-H CRC, MLH1 gene expression in CRC, and DNA methylation in CRC. The association between rs1800734 and MSI-H CRCs, previously reported in Ontario and Newfoundland, was replicated in the Seattle sample. Two additional SNPs, in strong linkage disequilibrium with rs1800734, showed strong associations with MLH1 promoter methylation, loss of MLH1 protein, and MSI-H CRC in all three samples. The logistic regression model of MSI-H CRC that included MLH1-promoter-methylation status and MLH1 immunohistochemistry status fit most parsimoniously in all three samples combined. When rs1800734 was added to this model, its effect was not statistically significant (P-value  = 0.72 vs. 2.3×10(-4) when the SNP was examined alone)., Conclusions/significance: The observed association of rs1800734 with MSI-H CRC occurs through its effect on the MLH1 promoter methylation, MLH1 IHC deficiency, or both.

Background and Aims: Colorectal cancer (CRC) is the second most frequent cancer in developed countries. Newfoundland has the highest incidence of CRC in Canada and the highest rate of familial CRC yet reported in the world. To determine the impact of mutations in known CRC susceptibility genes and the contribution of the known pathways to the development of hereditary CRC, an incident cohort of 750 patients with CRC (708 different families) from the Newfoundland population was studied., Methods: Microsatellite instability (MSI) testing was performed on tumours, together with immunohistochemistry analysis for mismatch repair (MMR) genes. Where indicated, DNA sequencing and multiplex ligation-dependent probe amplifications of MMR genes and APC was undertaken. DNA from all patients was screened for MUTYH mutations. The presence of the BRAF variant, p.V600E, and of MLH1 promoter methylation was also tested in tumours., Results: 4.6% of patients fulfilled the Amsterdam criteria (AC), and an additional 44.6% fulfilled the revised Bethesda criteria. MSI-high (MSI-H) was observed in 10.7% (n=78) of 732 tumours. In 3.6% (n=27) of patients, CRC was attributed to 12 different inherited mutations in six known CRC-related genes associated with chromosomal instability or MSI pathways. Seven patients (0.9%) carried a mutation in APC or biallelic mutations in MUTYH. Of 20 patients (2.7%) with mutations in MMR genes, 14 (70%) had one of two MSH2 founder mutations. 17 of 28 (61%) AC families did not have a genetic cause identified, of which 15 kindreds fulfilled the criteria for familial CRC type X (FCCTX)., Conclusions: Founder mutations accounted for only 2.1% of cases and this was insufficient to explain the high rate of familial CRC. Many of the families classified as FCCTX may have highly penetrant mutations segregating in a Mendelian-like manner. These families will be important for identifying additional CRC susceptibility loci.

Objective: Although a large body of epidemiological research suggests that red meat intake increases the risk of colorectal cancer, little is known regarding how such an association varies across populations and types of red meat. The objective of this study was to assess whether an association exists between the intakes of total red meat and pickled red meat and the risk of colorectal cancer in study subjects residing in Newfoundland and Labrador., Methods: This case-control study of 1,204 residents of Newfoundland and Labrador was part of a larger study on colorectal cancer. Personal history food frequency questionnaires were used to collect retrospective data from 518 individuals diagnosed with colorectal cancer and 686 controls. Intakes were ranked and divided into tertiles. Logistic regression was used to examine the possible association between meat intakes and colorectal cancer diagnosis while controlling for possible confounding factors., Results: A positive, but non-statistically significant, association between total red meat intake and CRC was observed in this study. Pickled red meat consumption was found to be significantly associated with an increased risk of CRC (men, OR = 2.07, 95% CI 1.37-3.15; women, OR = 2.51, 95% CI 1.45-4.32), the odds ratios increasing with each tertile of consumption, suggesting a dose-response effect., Conclusion: Intake of pickled red meat appears to increase the risk of colorectal cancer in Newfoundland and Labrador.

Background: The serrated pathway represents a distinct molecular pathway of colorectal carcinogenesis and is associated with the p.V600E BRAF mutation. The objective of this study is to characterize the cancer family history and clinicopathologic features of colorectal cancer (CRC) patients according to the microsatellite instability (MSI) and BRAF mutation status of their tumors., Methods: The tumors from 558 population-based CRC patients underwent pathologic examination and molecular analysis for MSI, BRAF, and germline mutations in mismatch repair genes MUTYH and APC. The cancer history in first-degree relatives (FDR) of index patients was ascertained., Results: The risk of CRC in FDRs of index patients with MSI-H BRAF mutation [hazard ratio (HR) = 2.49; 95% confidence interval (95% CI), 1.57- 3.93] and microsatellite-stable BRAF mutation tumors (HR = 1.64; 95% CI, 1.01-2.66) was significantly elevated compared with FDRs of index patients with microsatellite-stable BRAF wild-type tumors. The incidence of nonmelanoma skin cancer was also significantly elevated in FDRs of patients with BRAF mutation CRC (HR = 2.52; 95% CI, 1.31-4.86). Furthermore, BRAF mutation CRC was associated with a distinct clinical, molecular, and pathologic phenotype., Conclusions: The increased incidence of cancer in FDRs of index CRC patients with the p.V600E BRAF mutation may be explained by a genetic predisposition to develop cancer through the serrated pathway of colorectal carcinogenesis., Impact: Family members of BRAF CRC patients have an increased predisposition to develop cancer. Future work should aim to identify the causative genetic factors.

Objective: Newfoundland and Labrador (NL) has the highest incidence rate of both colorectal cancer (CRC) and smoking prevalence in Canada. The objective of this study was to examine if CRC is associated with smoking in this population., Methods: Newly diagnosed cases identified between 1999 and 2003 were frequency-matched by 5-year age group and sex with controls selected from the residents of NL through random digit dialing. A total of 702 cases and 717 controls consented to participate in the study and completed a set of self-administered questionnaires. Measures of tobacco use included type of tobacco, age of initiation of smoking, years of smoking, years since started smoking, number of cigarettes smoked daily, pack years, and years since abstention from smoking. Odds ratios were estimated using multivariate logistic regression., Results: In comparison with non-smokers, former and current smokers were at a significantly elevated risk of CRC with corresponding odds ratios of 1.36 and 1.96. The risk significantly increased with cigarette smoking years, the amount of cigarettes smoked daily, and cigarette pack years. The risk significantly decreased with years of abstention from smoking cigarettes. This association was stronger among drinkers and in men. In addition, this effect was observed to be slightly stronger for rectum than colon cancer., Discussion: In summary, cigarette smoking increased the risk of CRC in the NL population. The risk of CRC associated with cigarette smoking varies by sex, drinking status, and site of CRC.

Background: Lynch syndrome is caused by inherited mutations in DNA mismatch repair genes (primarily MSH2, MLH1, MSH6, and PMS2) and is one of the most prevalent inherited cancer syndromes. Several models have been developed to predict the occurrence of Lynch syndrome in high-risk patients and families, but it is not known how these models compare with one another or how they perform for colorectal cancer patients from the general population. We used data from such patients to test the ability of four models--Leiden, MMRpredict, PREMM(1,2), and MMRpro--to distinguish between those who did and did not carry DNA mismatch repair gene mutations., Methods: We studied a consecutive series of 725 patients who were younger than 75 years at colorectal cancer diagnosis and whose DNA mismatch repair gene mutation status was available; 18 of the 725 patients carried such a mutation. For each model, we calculated the risk score, compared the observed number of mutations with the expected number, and determined the receiver operating characteristics. All statistical tests were two-sided., Results: Although all four models overestimated the probability of a mutation (range = 1.2- to 4.3-fold), especially in low-risk patients, they could discriminate between carriers and noncarriers of a mismatch repair mutation. The areas under the receiver operating characteristics curves from the four models ranged from 0.91 to 0.96. Carriers of mutations in the MSH6 or PMS2 genes had lower risk scores than carriers of MSH2 or MLH1 mutations. For example, the MMRpredict model gave median risk scores of 24% and 94% (P < .015) for MSH6-PMS2 and MSH2-MLH1 mutation carriers, respectively. For the Leiden, MMRpredict, and PREMM(1,2) models, correcting the risk scores for bias introduced by family size improved their power to discriminate between carriers and noncarriers. After correcting for family size, the best model was MMRpredict, which achieved a sensitivity of 94% (95% confidence interval [CI] = 73% to 99%) and a specificity of 91% (95% CI = 88% to 93%) and identified a smaller proportion of patients than the revised Bethesda criteria as those who should undergo additional molecular or immunohistochemical testing (11% vs 50%)., Conclusion: MMRpredict was the best-performing model for identifying colorectal cancer patients who are at high risk of carrying a DNA mismatch repair gene mutation and thus should be screened for Lynch syndrome.

The most important indicator of colorectal cancer (CRC) risk is the presence of family history of the disease. Inherited genetic changes, such as single nucleotide polymorphisms, in key candidate genes may contribute to CRC risk. We investigated whether promoter polymorphisms in DNA mismatch repair (MMR) genes MSH2 and MSH6 are associated with the risk of CRC. We genotyped 929 CRC patients and 1098 control subjects from Ontario, and 467 patients and 344 controls from Newfoundland and Labrador, for two promoter polymorphisms in the MMR genes MSH2 and MSH6 using the fluorogenic 5' nuclease assay. We used unconditional logistic regression to evaluate the association between each polymorphism and CRC after adjusting for age and sex. The associations between polymorphisms and tumor clinicopathological features were evaluated with a Pearson's chi-squared test or Fisher's exact test. All statistical tests were two sided. We observed strong associations between the MSH2 -118T>C polymorphism and family history of CRC based on the Amsterdam criteria I (P = 0.005) and Amsterdam criteria I and II (P = 0.036) among cases from Ontario. This association was especially evident among female CRC patients in Ontario (for Amsterdam criteria I, and I and II combined, P = 0.003 and P = 0.0001, respectively). The MSH2 -118T>C polymorphism was associated with strong family history of CRC in Ontario patients.

Background: Although up to 30% of patients with colorectal cancer have a positive family history of colorectal neoplasia, few colorectal cancers can be explained by mutations in high-penetrance genes. We investigated whether polymorphisms in DNA mismatch repair genes are associated with the risk of colorectal cancer., Methods: We genotyped 929 case patients and 1098 control subjects from Ontario and 430 case patients and 275 control subjects from Newfoundland and Labrador for five polymorphisms in the mismatch repair genes MLH1 and MSH2 with the fluorogenic 5' nuclease assay. Tumor microsatellite instability (MSI) was determined with a polymerase chain reaction-based method; MSI status was assigned as high (MSI-H, > or = 30% unstable markers among all markers tested), low (MSI-L, <30% markers unstable), or stable (MSS, no unstable markers). We used unconditional logistic regression to evaluate the association between each polymorphism and colorectal cancer after adjusting for age and sex. The associations between polymorphisms and tumor clinicopathologic features were evaluated with a Pearson's chi-square or Fisher's exact test. All statistical tests were two-sided., Results: We observed strong associations between the MLH1 -93G>A polymorphism and MSI-H tumors among case patients from Ontario (P = .001) and Newfoundland (P = .003). When compared with the control populations, homozygosity for the MLH1 -93G>A variant allele was associated with MSI-H tumors among case patients in Ontario (adjusted odds ratio [OR] = 3.23, 95% confidence interval [CI] = 1.65 to 6.30) and in Newfoundland (OR = 8.88, 95% CI = 2.33 to 33.9), as was heterozygosity among case patients in Ontario (OR = 1.84, 95% CI = 1.20 to 2.83) and in Newfoundland (OR = 2.56, 95% CI = 1.14 to 5.75). Genotype frequencies were similar among case patients with MSS and MSI-L tumors and control subjects, and the majority of homozygous variant carriers had MSS tumors. Among case patients from Ontario, an association between the MLH1 -93G>A polymorphism and a strong family history of colorectal cancer (for Amsterdam criteria I and II, P = .004 and P = .02, respectively) was observed., Conclusion: In two patient populations, the MLH1 -93G>A polymorphism was associated with an increased risk of MSI-H colorectal cancer.

Newfoundland has the highest rate of colorectal cancer (CRC) of any Canadian province. In order to investigate the factors, especially genetic components, responsible for CRC we established the Newfoundland Colorectal Cancer Registry. In a 5-year period we examined every case of CRC diagnosed under the age of 75 years and obtained consent from 730 cases. Careful analysis of family history was used to assign a familial cancer risk, based on established criteria. We observed that 3.7% of CRC cases came from families meeting the Amsterdam II criteria and a further 0.9% of cases involved familial adenomatous polyposis (FAP). An additional 43% of cases met one or more of the revised Bethesda criteria and 31% of all cases had a first-degree relative affected with CRC. We compared the Newfoundland data with data from the province of Ontario, where the same recruitment and risk-assessment criteria were used. In all categories, the indicators of familial risk were significantly higher in Newfoundland. These data were also compared to results published from 13 other population-based studies worldwide. In every category the proportion of Newfoundland cases meeting the criteria was higher than in any other population. The mean differences were: 3.5-fold greater for FAP, 2.8-fold higher for Amsterdam criteria, 2.0-fold higher for Bethesda criteria and 1.9-fold higher for the number of affected first-degree relatives. We conclude that the high incidence of CRC in Newfoundland may be attributable to genetic, or at least familial, factors. In the high-risk families we provide evidence for the involvement of founder mutations in the APC and MSH2 genes.

Purpose: Newfoundland has one of the highest rates of colorectal cancer in North America. The most common hereditary form of colorectal cancer is hereditary nonpolyposis colorectal cancer caused by mutations in genes involved in mismatch repair. Our purpose was to determine the proportion of hereditary colorectal cancer and to determine the genetic basis of disease in both population and clinically referred cohorts from Newfoundland., Experimental Design: Seventy-eight colorectal cancer patients were accrued over a 2-year period from the Avalon Peninsula of Newfoundland. We also examined 31 hereditary nonpolyposis colorectal cancer-like families, which had been referred to the Provincial Medical Genetics Program. Tumors from probands were tested by immunohistochemistry for deficiencies in MLH1, MSH2, and MSH6 proteins and tested for DNA microsatellite instability. Mutation analyses of MLH1, MSH2, and MSH6 were undertaken by direct sequencing and an assay to detect deletions, amplifications, and rearrangements in MSH2 and MLH1., Results: We identified eight population-based families that fulfill the Amsterdam I or II criteria, 4 (50%) of which seem to have hereditary cancer not attributable to the most commonly mutated mismatch repair genes. In addition, in 16 of 21 (76%) referred families fulfilling Amsterdam I or II criteria, no mutations were found in the three most commonly altered mismatch repair genes, and tumor analyses corroborated these findings., Conclusions: It seems that strong and novel genetic causes of hereditary colorectal cancer are responsible for a high proportion of colorectal cancer in this population. Conditions are suitable for the identification of these genes by linkage studies of large Newfoundland cancer families.