Mendelian randomization study of height and risk of colorectal cancer

BACKGROUND

For men and women, taller height is associated with increased risk of all cancers combined. For colorectal cancer (CRC), it is unclear whether the differential association of height by sex is real or is due to confounding or bias inherent in observational studies. We performed a Mendelian randomization study to examine the association between height and CRC risk.

METHODS

To minimize confounding and bias, we derived a weighted genetic risk score predicting height (using 696 genetic variants associated with height) in 10,226 CRC cases and 10,286 controls. Logistic regression was used to estimate odds ratios (OR) and 95% confidence intervals (95% CI) for associations between height, genetically predicted height and CRC.

RESULTS

Using conventional methods, increased height (per 10-cm increment) was associated with increased CRC risk (OR = 1.08, 95% CI = 1.02-1.15). In sex-specific analyses, height was associated with CRC risk for women (OR = 1.15, 95% CI = 1.05-1.26), but not men (OR = 0.98, 95% CI = 0.92-1.05). Consistent with these results, carrying greater numbers of (weighted) height-increasing alleles (per 1-unit increase) was associated with higher CRC risk for women and men combined (OR = 1.07, 95% CI = 1.01-1.14) and for women (OR = 1.09, 95% CI =  .01-1.19). There was weaker evidence of an association for men (OR = 1.05, 95% CI = 0.96-1.15).

CONCLUSION

We provide evidence for a causal association between height and CRC for women. The CRC-height association for men remains unclear and warrants further investigation in other large studies.

A new GWAS and meta-analysis with 1000Genomes imputation identifies novel risk variants for colorectal cancer

Genome-wide association studies (GWAS) of colorectal cancer (CRC) have identified 23 susceptibility loci thus far. Analyses of previously conducted GWAS indicate additional risk loci are yet to be discovered. To identify novel CRC susceptibility loci, we conducted a new GWAS and performed a meta-analysis with five published GWAS (totalling 7,577 cases and 9,979 controls of European ancestry), imputing genotypes utilising the 1000 Genomes Project. The combined analysis identified new, significant associations with CRC at 1p36.2 marked by rs72647484 (minor allele frequency [MAF] = 0.09) near CDC42 and WNT4 (P = 1.21 × 10(-8), odds ratio [OR] = 1.21 ) and at 16q24.1 marked by rs16941835 (MAF = 0.21, P = 5.06 × 10(-8); OR = 1.15) within the long non-coding RNA (lncRNA) RP11-58A18.1 and ~500 kb from the nearest coding gene FOXL1. Additionally we identified a promising association at 10p13 with rs10904849 intronic to CUBN (MAF = 0.32, P = 7.01 × 10(-8); OR = 1.14). These findings provide further insights into the genetic and biological basis of inherited genetic susceptibility to CRC. Additionally, our analysis further demonstrates that imputation can be used to exploit GWAS data to identify novel disease-causing variants.

Mendelian Randomization Study of Body Mass Index and Colorectal Cancer Risk

BACKGROUND

High body mass index (BMI) is consistently linked to increased risk of colorectal cancer for men, whereas the association is less clear for women. As risk estimates from observational studies may be biased and/or confounded, we conducted a Mendelian randomization study to estimate the causal association between BMI and colorectal cancer.

METHODS

We used data from 10,226 colorectal cancer cases and 10,286 controls of European ancestry. The Mendelian randomization analysis used a weighted genetic risk score, derived from 77 genome-wide association study-identified variants associated with higher BMI, as an instrumental variable (IV). We compared the IV odds ratio (IV-OR) with the OR obtained using a conventional covariate-adjusted analysis.

RESULTS

Individuals carrying greater numbers of BMI-increasing alleles had higher colorectal cancer risk [per weighted allele OR, 1.31; 95% confidence interval (CI), 1.10-1.57]. Our IV estimation results support the hypothesis that genetically influenced BMI is directly associated with risk for colorectal cancer (IV-OR per 5 kg/m(2), 1.50; 95% CI, 1.13-2.01). In the sex-specific IV analyses higher BMI was associated with higher risk of colorectal cancer among women (IV-OR per 5 kg/m(2), 1.82; 95% CI, 1.26-2.61). For men, genetically influenced BMI was not associated with colorectal cancer (IV-OR per 5 kg/m(2), 1.18; 95% CI, 0.73-1.92).

CONCLUSIONS

High BMI was associated with increased colorectal cancer risk for women. Whether abdominal obesity, rather than overall obesity, is a more important risk factor for men requires further investigation.

IMPACT

Overall, conventional epidemiologic and Mendelian randomization studies suggest a strong association between obesity and the risk of colorectal cancer.

Prediagnostic Physical Activity and Colorectal Cancer Survival: Overall and Stratified by Tumor Characteristics

BACKGROUND

Physical activity is associated with a lower incidence of colorectal cancer; however, the relationship of physical activity with colorectal cancer survival is not yet clear. We evaluated the association between prediagnostic physical activity and colorectal cancer survival, overall and accounting for tumor markers associated with colorectal cancer survival: BRAF and KRAS mutation status and microsatellite instability (MSI) status.

METHODS

Participants were 20- to 74-year-old colorectal cancer patients diagnosed between 1998 and 2007 from the population-based Seattle Colon Cancer Family Registry (S-CCFR). Self-reported physical activity in the years preceding colorectal cancer diagnosis was summarized as average metabolic equivalent task hours per week (MET-h/wk; n = 1,309). Somatic BRAF and KRAS mutations and MSI status were evaluated on a subset of patients (n = 1043). Cox regression was used to estimate HRs and 95% confidence intervals (CI) for overall and disease-specific survival after adjusting for relevant confounders. Stratified analyses were conducted across categories of BRAF, KRAS, and MSI, as well as tumor stage and site.

RESULTS

Higher prediagnostic recreational physical activity was associated with significantly more favorable overall survival (HR for highest vs. lowest category, 0.70; 95% CI, 0.52-0.96); associations were similar for colorectal cancer-specific survival. Results consistently indicated a favorable association with physical activity across strata defined by tumor characteristics.

CONCLUSION

Individuals who were physically active before colorectal cancer diagnosis experienced better survival than those who were inactive or minimally active.

IMPACT

Our results support existing physical activity recommendations for colorectal cancer patients and suggest that the beneficial effect of activity is not specific to a particular molecular phenotype of colorectal cancer.

Association of aspirin and NSAID use with risk of colorectal cancer according to genetic variants

IMPORTANCE

Use of aspirin and other nonsteroidal anti-inflammatory drugs (NSAIDs) is associated with lower risk of colorectal cancer.

OBJECTIVE

To identify common genetic markers that may confer differential benefit from aspirin or NSAID chemoprevention, we tested gene × environment interactions between regular use of aspirin and/or NSAIDs and single-nucleotide polymorphisms (SNPs) in relation to risk of colorectal cancer.

DESIGN, SETTING, AND PARTICIPANTS

Case-control study using data from 5 case-control and 5 cohort studies initiated between 1976 and 2003 across the United States, Canada, Australia, and Germany and including colorectal cancer cases (n=8634) and matched controls (n=8553) ascertained between 1976 and 2011. Participants were all of European descent.

EXPOSURES

Genome-wide SNP data and information on regular use of aspirin and/or NSAIDs and other risk factors.

MAIN OUTCOMES AND MEASURES

Colorectal cancer.

RESULTS

Regular use of aspirin and/or NSAIDs was associated with lower risk of colorectal cancer (prevalence, 28% vs 38%; odds ratio [OR], 0.69 [95% CI, 0.64-0.74]; P = 6.2 × 10(-28)) compared with nonregular use. In the conventional logistic regression analysis, the SNP rs2965667 at chromosome 12p12.3 near the MGST1 gene showed a genome-wide significant interaction with aspirin and/or NSAID use (P = 4.6 × 10(-9) for interaction). Aspirin and/or NSAID use was associated with a lower risk of colorectal cancer among individuals with rs2965667-TT genotype (prevalence, 28% vs 38%; OR, 0.66 [95% CI, 0.61-0.70]; P = 7.7 × 10(-33)) but with a higher risk among those with rare (4%) TA or AA genotypes (prevalence, 35% vs 29%; OR, 1.89 [95% CI, 1.27-2.81]; P = .002). In case-only interaction analysis, the SNP rs16973225 at chromosome 15q25.2 near the IL16 gene showed a genome-wide significant interaction with use of aspirin and/or NSAIDs (P = 8.2 × 10(-9) for interaction). Regular use was associated with a lower risk of colorectal cancer among individuals with rs16973225-AA genotype (prevalence, 28% vs 38%; OR, 0.66 [95% CI, 0.62-0.71]; P = 1.9 × 10(-30)) but was not associated with risk of colorectal cancer among those with less common (9%) AC or CC genotypes (prevalence, 36% vs 39%; OR, 0.97 [95% CI, 0.78-1.20]; P = .76).

CONCLUSIONS AND RELEVANCE

In this genome-wide investigation of gene × environment interactions, use of aspirin and/or NSAIDs was associated with lower risk of colorectal cancer, and this association differed according to genetic variation at 2 SNPs at chromosomes 12 and 15. Validation of these findings in additional populations may facilitate targeted colorectal cancer prevention strategies.

Association of the colorectal CpG island methylator phenotype with molecular features, risk factors, and family history

BACKGROUND

The CpG island methylator phenotype (CIMP) represents a subset of colorectal cancers characterized by widespread aberrant DNA hypermethylation at select CpG islands. The risk factors and environmental exposures contributing to etiologic heterogeneity between CIMP and non-CIMP tumors are not known.

METHODS

We measured the CIMP status of 3,119 primary population-based colorectal cancer tumors from the multinational Colon Cancer Family Registry. Etiologic heterogeneity was assessed by a case-case study comparing risk factor frequency of colorectal cancer cases with CIMP and non-CIMP tumors using logistic regression to estimate the case-case odds ratio (ccOR).

RESULTS

We found associations between tumor CIMP status and MSI-H (ccOR = 7.6), BRAF V600E mutation (ccOR = 59.8), proximal tumor site (ccOR = 9; all P < 0.0001), female sex [ccOR = 1.8; 95% confidence interval (CI), 1.5-2.1], older age (ccOR = 4.0 comparing over 70 years vs. under 50; 95% CI, 3.0-5.5), and family history of CRC (ccOR = 0.6; 95% CI, 0.5-0.7). While use of NSAIDs varied by tumor CIMP status for both males and females (P = 0.0001 and P = 0.02, respectively), use of multivitamin or calcium supplements did not. Only for female colorectal cancer was CIMP status associated with increased pack-years of smoking (Ptrend < 0.001) and body mass index (BMI; Ptrend = 0.03).

CONCLUSIONS

The frequency of several colorectal cancer risk factors varied by CIMP status, and the associations of smoking and obesity with tumor subtype were evident only for females.

IMPACT

Differences in the associations of a unique DNA methylation-based subgroup of colorectal cancer with important lifestyle and environmental exposures increase understanding of the molecular pathologic epidemiology of this heavily methylated subset of colorectal cancer. Cancer Epidemiol Biomarkers Prev; 24(3); 512-9. ©2015 AACR.

Oral bisphosphonate use and risk of postmenopausal endometrial cancer

PURPOSE

Bisphosphonates are common medications used for the treatment of osteoporosis and are also used to reduce metastases to bone in patients with cancer. Several studies, including the Women's Health Initiative (WHI), have found that use of bisphosphonates is associated with reduced risk of developing breast cancer, but less is known about associations with other common malignancies. This study was aimed at examining the effects of bisphosphonates on the risk of endometrial cancer.

METHODS

We evaluated the relationship between use of oral bisphosphonates and endometrial cancer risk in a cohort of 89,918 postmenopausal women participating in the WHI. A detailed health interview was conducted at baseline, and bisphosphonate use was ascertained from an inventory of regularly used medications at baseline and over follow-up. All women had an intact uterus at the time of study entry.

RESULTS

During a median follow-up of 12.5 years, 1,123 women were diagnosed with incident invasive endometrial cancer. Ever use of bisphosphonates was associated with reduced endometrial cancer risk (adjusted hazard ratio, 0.80; 95% CI, 0.64 to 1.00; P = .05), with no interactions observed with age, body mass index, or indication for use.

CONCLUSION

In this large prospective cohort of postmenopausal women, bisphosphonate use was associated with a statistically significant reduction in endometrial cancer risk.

Dual role of TGFBR1 as a modifier of colorectal cancer risk

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Background: Experimental and clinical evidence suggests that constitutively decreased Transforming Growth Factor Beta type I receptor (TGFBR1) signaling predisposes to colorectal cancer (CRC) development. However, associations between TGFBR1 variants and CRC risk in case-control studies have been inconsistent. Methods: We utilized 1,043 CRC cases and their 1,627 unaffected sibling controls obtained from the Colon Cancer Family Registry (C-CFR). Individuals were genotyped for twelve TGFBR1 haplotype tagging SNPs. SNPs associated with CRC risk were validated in 261 CRC cases and 531 controls of African American ancestry and 990 CRC cases and 3,427 controls of Han Chinese ancestry. Validated SNPs were functionally characterized with respect to TGFBR1 expression and TGF-β signaling. Results: The TGFBR1 rs7034462-TT genotype was associated with CRC risk in C-CFR participants (OR 3.80[1.46-9.85]) and African Americans (OR 8.16[2.07-32.08]) (see Table). The TT genotype was associated with stage III and stage IV at diagnosis in C-CFR participants (OR 2.99[1.15-7.81] and OR 9.38[1.54-57.28]) and African Americans (OR 5.89[1.15-30.02] and OR 12.75[1.88-86.33]), respectively. The rs7034462-CT genotype was associated with decreased risk for CRC in African Americans (OR 0.55[0.31-0.99]) and Han Chinese (OR 0.67[0.48-0.95]) (see table). Cells carrying the rs7034462-TT genotype exhibited decreased constitutive TGFBR1 expression, increased SMAD7 expression, and decreased TGF-β signaling. Conclusions: The TGFBR1 rs7034462-T allele has dual, opposite roles with respect to CRC risk. The rare rs7034462-TT genotype is a moderate penetrance genotype associated with risk for CRC and advanced stage disease at diagnosis. In contrast, the common rs7034462-CT genotype is associated with decreased CRC risk. [Table: see text]

Role of tumour molecular and pathology features to estimate colorectal cancer risk for first-degree relatives

OBJECTIVE

To estimate risk of colorectal cancer (CRC) for first-degree relatives of CRC cases based on CRC molecular subtypes and tumour pathology features.

DESIGN

We studied a cohort of 33,496 first-degree relatives of 4853 incident invasive CRC cases (probands) who were recruited to the Colon Cancer Family Registry through population cancer registries in the USA, Canada and Australia. We categorised the first-degree relatives into four groups: 28,156 of 4095 mismatch repair (MMR)-proficient probands, 2302 of 301 MMR-deficient non-Lynch syndrome probands, 1799 of 271 suspected Lynch syndrome probands and 1239 of 186 Lynch syndrome probands. We compared CRC risk for first-degree relatives stratified by the absence or presence of specific tumour molecular pathology features in probands across each of these four groups and for all groups combined.

RESULTS

Compared with first-degree relatives of MMR-proficient CRC cases, a higher risk of CRC was estimated for first-degree relatives of CRC cases with suspected Lynch syndrome (HR 2.06, 95% CI 1.59 to 2.67) and with Lynch syndrome (HR 5.37, 95% CI 4.16 to 6.94), but not with MMR-deficient non-Lynch syndrome (HR 1.04, 95% CI 0.82 to 1.31). A greater risk of CRC was estimated for first-degree relatives if CRC cases were diagnosed before age 50 years, had proximal colon cancer or if their tumours had any of the following: expanding tumour margin, peritumoral lymphocytes, tumour-infiltrating lymphocytes or synchronous CRC.

CONCLUSIONS

Molecular pathology features are potentially useful to refine screening recommendations for first-degree relatives of CRC cases and to identify which cases are more likely to be caused by genetic or other familial factors.

Association between molecular subtypes of colorectal cancer and patient survival

BACKGROUND AND AIMS

Colorectal cancer (CRC) is a heterogeneous disease that can develop via several pathways. Different CRC subtypes, identified based on tumor markers, have been proposed to reflect these pathways. We evaluated the significance of these previously proposed classifications to survival.

METHODS

Participants in the population-based Seattle Colon Cancer Family Registry were diagnosed with invasive CRC from 1998 through 2007 in western Washington State (N = 2706), and followed for survival through 2012. Tumor samples were collected from 2050 participants and classified into 5 subtypes based on combinations of tumor markers: type 1 (microsatellite instability [MSI]-high, CpG island methylator phenotype [CIMP] -positive, positive for BRAF mutation, negative for KRAS mutation); type 2 (microsatellite stable [MSS] or MSI-low, CIMP-positive, positive for BRAF mutation, negative for KRAS mutation); type 3 (MSS or MSI low, non-CIMP, negative for BRAF mutation, positive for KRAS mutation); type 4 (MSS or MSI-low, non-CIMP, negative for mutations in BRAF and KRAS); and type 5 (MSI-high, non-CIMP, negative for mutations in BRAF and KRAS). Multiple imputation was used to impute tumor markers for those missing data on 1-3 markers. We used Cox regression to estimate hazard ratios (HR) and 95% confidence intervals (CI) for associations of subtypes with disease-specific and overall mortality, adjusting for age, sex, body mass, diagnosis year, and smoking history.

RESULTS

Compared with participants with type 4 tumors (the most predominant), participants with type 2 tumors had the highest disease-specific mortality (HR = 2.20, 95% CI: 1.47-3.31); subjects with type 3 tumors also had higher disease-specific mortality (HR = 1.32, 95% CI: 1.07-1.63). Subjects with type 5 tumors had the lowest disease-specific mortality (HR = 0.30, 95% CI: 0.14-0.66). Associations with overall mortality were similar to those with disease-specific mortality.

CONCLUSIONS

Based on a large, population-based study, CRC subtypes, defined by proposed etiologic pathways, are associated with marked differences in survival. These findings indicate the clinical importance of studies into the molecular heterogeneity of CRC.

A novel colorectal cancer risk locus at 4q32.2 identified from an international genome-wide association study

Only a fraction of colorectal cancer heritability is explained by known risk-conferring genetic variation. This study was designed to identify novel risk alleles in Europeans. We conducted a genome-wide association study (GWAS) meta-analysis of colorectal cancer in participants from a population-based case-control study in Israel (n = 1616 cases, 1329 controls) and a consortium study from the Colon Cancer Family Registry (n = 1977 cases, 999 controls). We used a two-stage (discovery-replication) GWAS design, followed by a joint meta-analysis. A combined analysis identified a novel susceptibility locus that reached genome-wide significance on chromosome 4q32.2 [rs35509282, risk allele = A (minor allele frequency = 0.09); odds ratio (OR) per risk allele = 1.53; P value = 8.2 × 10(-9); nearest gene = FSTL5]. The direction of the association was consistent across studies. In addition, we confirmed that 14 of 29 previously identified susceptibility variants were significantly associated with risk of colorectal cancer in this study. Genetic variation on chromosome 4q32.2 is significantly associated with risk of colorectal cancer in Ashkenazi Jews and Europeans in this study.

Red meat intake, NAT2, and risk of colorectal cancer: a pooled analysis of 11 studies

BACKGROUND

Red meat intake has been associated with risk of colorectal cancer, potentially mediated through heterocyclic amines. The metabolic efficiency of N-acetyltransferase 2 (NAT2) required for the metabolic activation of such amines is influenced by genetic variation. The interaction between red meat intake, NAT2 genotype, and colorectal cancer has been inconsistently reported.

METHODS

We used pooled individual-level data from the Colon Cancer Family Registry and the Genetics and Epidemiology of Colorectal Cancer Consortium. Red meat intake was collected by each study. We inferred NAT2 phenotype based on polymorphism at rs1495741, highly predictive of enzyme activity. Interaction was assessed using multiplicative interaction terms in multivariate-adjusted models.

RESULTS

From 11 studies, 8,290 colorectal cancer cases and 9,115 controls were included. The highest quartile of red meat intake was associated with increased risk of colorectal cancer compared with the lowest quartile [OR, 1.41; 95% confidence interval (CI), 1.29-1.55]. However, a significant association was observed only for studies with retrospective diet data, not for studies with diet prospectively assessed before cancer diagnosis. Combining all studies, high red meat intake was similarly associated with colorectal cancer in those with a rapid/intermediate NAT2 genotype (OR, 1.38; 95% CI, 1.20-1.59) as with a slow genotype (OR, 1.43; 95% CI, 1.28-1.61; P interaction = 0.9).

CONCLUSION

We found that high red meat intake was associated with increased risk of colorectal cancer only from retrospective case-control studies and not modified by NAT2 enzyme activity.

IMPACT

Our results suggest no interaction between NAT2 genotype and red meat intake in mediating risk of colorectal cancer.

Abstract 2187: Colorectal cancer survival is not associated with genetic variants related to risk of other cancers: The GECCO study

Background:

Colorectal cancer (CRC) is a major cause of morbidity and mortality. Previous genome-wide association studies (GWAS) have identified a large number of single nucleotide polymorphisms (SNPs) associated with CRC, at least one of which has also been found to be associated with CRC survival. Furthermore, some SNPs have demonstrated risk associations with multiple cancers (i.e. pleiotropy), including CRC. Together, this raises the possibility that SNPs associated with risk of other cancers may also be associated with survival after a diagnosis of CRC. To investigate this question, we evaluated 526 SNPs reported as strongly associated with risk of any type of cancer in the National Human Genome Research Institute GWAS catalog (as of 11/13/2013) for an association with CRC-specific and overall survival. This study utilized data available from multiple studies in the Genetic Epidemiology of Colorectal Cancer Consortium (GECCO).

Methods:

We evaluated 526 SNPs associated with risk of cancers other than CRC in six studies participating in GECCO: the Health Professionals Follow-up Study; the Nurses' Health Study; the Physicians' Health Study; the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial; the VITamins And Lifestyle Study; and the Women's Health Initiative. A total of 3,494 colorectal cancer cases were evaluated, of whom 1,223 (35%) died (830 from CRC, 24%) during follow-up (average median follow-up time of 6.8 years). Cox proportional hazards regression was used to calculate the per-allele hazard ratio (HR) and 95% confidence interval (95% CI) for the association between each SNP and CRC-specific or overall survival, adjusting for age at diagnosis, sex, study sample, and the first three principal components of genetic ancestry.

Results:

After Bonferroni correction for multiple comparisons (P = 0.05/526 = 9.51e-5), no SNPs were statistically significantly associated with either CRC-specific or overall survival. For CRC-specific survival, 35 SNPs showed a nominal association (p&lt;0.05), the strongest being breast cancer SNP rs6504950 in STXBP4 (HR = 1.19, 95% CI = 1.06-1.31, p = 0.0018). For overall survival, 38 SNPs showed a nominal association, the strongest being melanoma SNP rs1393350 in TYR (HR = 1.15, 95% CI = 1.06-1.26, p = 0.0012). More SNPs showed a nominal association with survival than expected by chance (0.05*526 = 26 SNPs).

Conclusion:

These preliminary results broadly suggest that CRC-specific and overall survival do not appear to be strongly associated with genetic variants related to incidence for other cancers. However, some suggestive evidence of nominal associations with survival supports further investigation. Planned future steps include the incorporation of two additional studies (Cancer Prevention Study II; Diet, Activity, and Lifestyle Study), as well as analyses stratified by factors such as cancer site, stage at diagnosis, and sex.

Citation Format: Jonathan M. Kocarnik, Michael N. Passarelli, Amanda I. Phipps, Andrew T. Chan, Manish Gala, Amit Joshi, Peter T. Campbell, Martha L. Slattery, John Potter, Emily White, Sonja Berndt, Ulrike Peters, Polly A. Newcomb. Colorectal cancer survival is not associated with genetic variants related to risk of other cancers: The GECCO study. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2187. doi:10.1158/1538-7445.AM2014-2187

Abstract 294: Blood lipids, colorectal adenomas, and non-adenomatous polyps: A comparison of associations from clinical measurements and Mendelian randomization

Background: Numerous studies have assessed associations between lipid levels and risk of colorectal neoplasia, but findings have been inconsistent. Recent genetic studies have identified &gt;100 loci associated with lipid levels. Knowledge of the magnitude and direction of genetic effects permits evaluation of allele scores that can serve as proxies for phenotypes.

Methods: We collected information on blood lipids as part of a colonoscopy study among enrollees, ages 25-79, of Group Health, a large healthcare system in Washington State. Low-density lipoprotein (LDL), high-density lipoprotein (HDL), triglycerides (TG), and total cholesterol (TC) measurements were extracted from electronic medical records for 98% of participants. For each participant, we identified the highest LDL, TG, and TC measurement (zenith) and lowest HDL measurement (nadir) prior to colonoscopy. All participants were genotyped for 96 single-nucleotide polymorphisms (SNPs) identified by the Global Lipids Genetics Consortium. For each lipid trait, we estimated 3 associations: 1) phenotype-polyp odds ratios (OR) with 95% confidence intervals (CI) comparing non-advanced adenoma cases to controls, advanced adenoma cases (≥10 mm in diameter, with villous components, or high-grade dysplasia) to controls, and non-adenomatous polyp cases to controls from polytomous logistic regression; 2) genotype-phenotype associations from linear regression; and 3) genotype-polyp ORs from two-stage linear-logistic regression.

Results: In total, 1,791 participants had information on phenotype and genotype (518 non-advanced adenoma cases, 139 advanced adenoma cases, 380 non-adenomatous polyp cases, and 754 polyp-free controls). Individuals with advanced adenomas were more likely than controls to have higher LDL and TG (adjusted OR per 20 mg/dL increase in zenith LDL: 1.16, CI 1.03-1.30 and OR per 40 mg/dL increase in zenith TG: 1.09, 1.03-1.16). Associations from allele scores were in the same direction (OR per increase in allele score scaled to be comparable to a 20 mg/dL LDL increase: 1.17, CI 0.78-1.75, and OR per increase in allele score scaled to be comparable to a 40 mg/dL TG increase: 1.12, 0.91-1.38). SNPs most strongly related to phenotype, however, were not associated with polyps, and SNPs that were, including variants of NAT2, MC4R, and APOE, may function through alternative pathways. Analyses among statin-naïve participants were not meaningfully different.

Conclusions: Mendelian randomization estimates did not achieve statistical significance, but the direction of associations suggests that polyps are more prevalent among those with inherited susceptibility to increased LDL and TG. Results also highlight difficulties interpreting results from Mendelian randomization analyses of traits with complex biology, given that variants may be pleiotropic and not suitable for use as instrumental variables.

Citation Format: Michael N. Passarelli, Polly A. Newcomb, Karen W. Makar, Andrea N. Burnett-Hartman, John D. Potter, Melissa P. Upton, Lee-Ching Zhu, Michael E. Rosenfeld, Stephen M. Schwartz, Carolyn M. Rutter. Blood lipids, colorectal adenomas, and non-adenomatous polyps: A comparison of associations from clinical measurements and Mendelian randomization. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 294. doi:10.1158/1538-7445.AM2014-294

Abstract 2176: Obesity and risk of colorectal cancer: A Mendelian randomization study

Background: Obesity has been consistently linked to higher risk of colorectal cancer (CRC) in men, whereas the association is generally lower in women. Although these findings come from well conducted epidemiologic studies, it is difficult to exclude all other explanations for associations in observational studies, such as measurement error and other forms of bias, reverse causality and confounding. Mendelian randomization studies, using instrumental variables (IVs), can overcome some of the inherent limitations of observational studies and provide an unbiased and unconfounded estimate of the causal association between an exposure and outcome.

Objective: We used genetic variants that are associated with body mass index (BMI) or waist-hip ratio (WHR) to examine the causal association between obesity and CRC.

Methods: We used epidemiologic and genetic data from 10 226 CRC cases and 10 286 controls of European ancestry from the Genetics and Epidemiology of Colorectal Cancer Consortium (GECCO) or the Colon Cancer Family Registry (CCFR). The primary Mendelian randomization analysis was performed using a genetic risk score, derived from 77 established “BMI-increasing” genetic variants, as an instrumental variable for higher BMI. We additionally derived a risk score for WHR using 47 variants for WHR. We compared the IV odds ratio (OR) with the OR obtained using a traditional multivariable logistic regression model adjusted for age, sex, smoking status, family history, aspirin use, and HRT use (women).

Results: For men and women combined, in traditional multivariable analysis, each 5 kg/m2 increase in BMI was associated with a 24% (95% confidence interval [CI]: 1.17-1.32) increase in risk of CRC. In the IV analysis, the OR was higher (IV-OR per 5 kg/m2=1.54, 95% CI: 1.15-2.06); however, the two estimates were not statistically significantly different (Pdifference=0.07). For men, there was a statistically significant association between BMI and CRC in traditional multivariable analysis (OR per 5kg/m2=1.33, 95% CI: 1.21-1.46), but no association in the IV analysis (IV-OR per 5 kg/m2=1.13, 95% CI: 0.70-1.83). The estimates however were not significantly different (Pdifference=0.56). In contrast, for women, the IV estimate (IV-OR per 5 kg/m2=1.94, 95% CI: 1.33-2.82) was significantly higher than the estimate from the traditional multivariable analysis (OR per 5 kg/m2=1.18, 95% CI: 1.11-1.25; Pdifference=0.01). In secondary analysis, we found a positive association between WHR and CRC in men (IV-OR per 0.1 unit increase=1.84, 95% CI: 1.02-3.31) but no statistically significant association in women (IV-OR per 0.1 unit increase=1.22, 95% CI: 0.75-1.98).

Conclusions: Obesity is independently associated with risk of CRC and may confer greater risk of CRC in women than previously reported. The mechanisms remain largely unknown; however these results suggest that visceral abdominal fat may be particularly important for promoting CRC in men.

Citation Format: Aaron P. Thrift, Sonja I. Berndt, Andrew T. Chan, Jenny Chang-Claude, Martha L. Slattery, Michelle Cotterchio, Graham Casey, John D. Potter, Polly A. Newcomb, Emily White, Hermann Brenner, Ulrike Peters, Peter T. Campbell. Obesity and risk of colorectal cancer: A Mendelian randomization study. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2176. doi:10.1158/1538-7445.AM2014-2176

Abstract 2172: Physical activity in relation to overall and colorectal cancer specific survival in the Seattle Colon Cancer Family Registry

Background

Previous studies have suggested that physical activity is associated with a reduced risk of colon cancer. The association of physical activity with colorectal cancer (CRC) survival, however, is less clear. Studies evaluating the association between post-diagnostic physical activity and CRC survival suggest a favorable survival among those who engage in regular physical activity after diagnosis. However, such studies are limited by the possibility of reverse causality since individuals engaging in regular physical activity after diagnosis may have had a better prognosis to begin with.

Methods

We evaluated the association between pre-diagnostic physical activity and survival, both overall and CRC-specific, within the Seattle Colon Cancer Family Registry (SCCFR), a prospective cohort of persons diagnosed with CRC between 1997 and 2002. All cases completed a risk-factor questionnaire including information on medical history, demographic and lifestyle factors, such as obesity and decade-specific recreational physical activity. Vital status and cause of death was determined through linkage to a regional cancer registry and National Death Index. Tumor markers (BRAF and KRAS mutation status) were evaluated for a subset of cases. Physical activity was summarized as average weekly metabolic equivalent-task hours (MET-h/week). Adjusted hazard ratios (HR) and 95% confidence limits (95%CI) were estimated using Cox regression.

Results

Primary analyses included 1171 persons who self-reported their physical activity status, of whom 471 died (292 deaths attributable to CRC; median follow-up 6.3 years). After adjusting for age at diagnosis, sex, body mass index and smoking status, those who engaged in physical activity had a significantly lower risk of dying from any cause compared to those who did not engage in any physical activity (HR 0.72, 95%CI 0.51-0.99; HR 0.62, 95%CI 0.44-0.87; and HR 0.60, 95%CI 0.43-0.85 for &gt;0-6.4, 6.4-19.2, and &gt;19.2 MET-h/wk, respectively; P for trend=0.035). Results for CRC-specific survival were similar and suggested improved survival among physically active individuals compared to those that were inactive, although no trend was evident (HR 0.81, 95%CI 0.51-1.28; HR 0.72, 95%CI 0.45-1.15; and HR 0.72, 95% CI 0.44-1.14 for &gt;0-6.4, 6.4-19.2, &gt;19.2 MET-h/wk respectively; P for trend= 0.52). Further adjustment for stage at diagnosis or BRAF and KRAS mutation status did not alter the results.

Conclusion

Our results suggest that individuals who are physically active prior to CRC diagnosis experience more favorable survival than those who are inactive. Increased physical activity was also associated with better CRC-specific survival, but this trend was not statistically significant. Continued follow-up of this and other larger cohorts is needed to further clarify the role of physical activity in CRC prognosis.

Citation Format: Sheetal S. Hardikar, Polly A. Newcomb, Michael N. Passarelli, Peter T. Campbell, Amanda I. Phipps. Physical activity in relation to overall and colorectal cancer specific survival in the Seattle Colon Cancer Family Registry. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2172. doi:10.1158/1538-7445.AM2014-2172

Abstract 299: Circulating microRNAs in association with colorectal neoplasia

Purpose: MicroRNAs (miRNAs) are non-coding regulatory RNAs that are stable in circulation and implicated in the etiology of many cancers including colorectal cancer (CRC). In this study we investigated whether candidate miRNAs could serve as blood-based biomarkers of colorectal adenoma.

Methods: We conducted a colonoscopy-based case-control study of men and women ages 50-79; this report includes data from 48 polyp-free controls, 43 advanced adenoma, 73 non-advanced adenomas, and 8 CRC cases. We selected 12 miRNA candidates that are highly expressed in adenoma tissue and have low expression in blood cells, in addition to miRNAs previously reported as biomarkers of adenoma. miRNAs were extracted from stored plasma samples, and copy number assessed with qRT-PCR. Odds ratios (ORs) and area-under-the-curve (AUC) from receiver-operator characteristic curves were estimated to quantify the association between plasma copy-number of these candidate miRNAs and each case group.

Results: No miRNA transcripts were associated with risk of adenoma or advanced adenomas, or with an AUC significantly above 0.5 that would indicate usefulness in discriminating either category of adenoma cases from controls. In contrast, statistically significant and strong associations (ORs&gt;5) with CRC were observed for 6 miRNA candidates, with corresponding AUCs significantly greater than 0.5.

Conclusions: Our results suggest that these candidate miRNAs, assayed with qRT-PCR, are unlikely to have clinical utility as blood-based screening biomarkers of adenomas. However, strong associations were observed with CRC. Circulating miRNAs may therefore have promise as potential early detection biomarkers to augment current CRC screening methods, but an optimal screening biomarker would detect pre-malignant colorectal adenomas as well as frank CRC.

Citation Format: Scott V. Adams, Polly A. Newcomb, Andrea N. Burnett-Hartman, Melissa P. Upton, Lee-Ching Zhu, Margaret Mandelson, John D. Potter, Karen W. Makar. Circulating microRNAs in association with colorectal neoplasia. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 299. doi:10.1158/1538-7445.AM2014-299

Abstract LB-276: Prospective study of body mass index and adult weight change with colorectal cancer survival, overall and by tumor microsatellite instability status

Background: Tumor features such as stage, grade, and microsatellite instability (MSI) status have relevance for colorectal cancer survival whereas the prognostic role of body mass index (BMI) is unclear. We assessed the association of BMI and adult weight gain on colorectal cancer survival, overall and by strata of sex and MSI.

Methods: Participants were identified from a multi-center cohort that includes 6,763 colorectal cancer patients with invasive colorectal cancer who were enrolled into the Colon Cancer Family Registry from 1997 to 2008. Vital status was updated through direct contact with patients/next-of-kin and/or linkage with mortality records. BMI 2 years before diagnosis, BMI at age 20 years, and adult weight gain were derived from self-reports of height and weight (i.e., weight 2 years before diagnosis and weight at age 20 years). Tumor MSI status was available for 4,987 patients. Multivariable, two-sided hazard ratios (HR) and 95% confidence intervals (CIs) were estimated from delayed-entry Cox proportional hazards models, controlling for age at diagnosis, TNM summary stage (i.e., I, II, III, IV or missing), smoking (current, former, never), and study center.

Results: After a maximum of 13.7 years of follow-up from enrollment to end-of-study (median: 5.3 years), 2,335 patients had died. Higher BMI 2 years before cancer diagnosis (per 5-kg/m2) was associated with higher risk of all-cause mortality overall (HR, 1.10; 95% CI, 1.05 to 1.14), with similar associations when stratified by sex (men: HR, 1.07; 95% CI, 1.02 to 1.14; women: HR, 1.11: 95% CI, 1.05 to 1.17; p-interaction: 0.18) and MSI status (MS-stable/MSI-low: HR, 1.08; 95% CI, 1.03 to 1.14; MSI-high, HR: 1.19; 95% CI, 1.02 to 1.40; p-interaction: 0.88). In joint models, with MS-stable/MSI-low and normal BMI as the referent group, risk of death was lower for those with MSI-high and normal BMI (HR: 0.77; 95% CI: 0.59 to 1.00), higher for MS-stable/MSI-low and high (≥30) BMI (HR: 1.23; 95% CI: 1.07 to 1.42), and essentially the same for MSI-high and high BMI (HR: 0.97; 95% CI: 0.72 to 1.30). Similar patterns of association were observed for BMI at age 20 years and when the outcome was colorectal cancer-specific mortality, although not all associations remained statistically significant for some of the smaller sub-group analyses. After controlling for BMI at age 20 years, adult weight gain was only modestly associated with all-cause mortality (per 5 kg HR: 1.01; 95% CI: 1.00 to 1.02; p-trend: 0.07).

Conclusion: High pre-diagnosis BMI was associated with increased mortality after colorectal cancer diagnosis; this association was consistent for men and women and by tumor MSI status. These results also suggest that obesity attenuates the survival advantage observed with MSI-high tumors.

Citation Format: Peter T. Campbell, Christina Newton, Polly A. Newcomb, Dennis Ahnen, John Baron, Sean Cleary, Michelle Cotterchio, A. Brad Farris, Jane Figueiredo, Roger C. Green, Loic Le Marchand, John McLaughlin, Amanda Phipps, John D. Potter, Andrew Renehan, Aung Ko Win, Noralane Lindor, Paul Limburg. Prospective study of body mass index and adult weight change with colorectal cancer survival, overall and by tumor microsatellite instability status. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr LB-276. doi:10.1158/1538-7445.AM2014-LB-276

No evidence of gene-calcium interactions from genome-wide analysis of colorectal cancer risk

BACKGROUND

Calcium intake may reduce risk of colorectal cancer, but the mechanisms remain unclear. Studies of interaction between calcium intake and SNPs in calcium-related pathways have yielded inconsistent results.

METHODS

To identify gene-calcium interactions, we tested interactions between approximately 2.7 million SNPs across the genome with self-reported calcium intake (from dietary or supplemental sources) in 9,006 colorectal cancer cases and 9,503 controls of European ancestry. To test for multiplicative interactions, we used multivariable logistic regression and defined statistical significance using the conventional genome-wide α = 5E-08.

RESULTS

After accounting for multiple comparisons, there were no statistically significant SNP interactions with total, dietary, or supplemental calcium intake.

CONCLUSIONS

We found no evidence of SNP interactions with calcium intake for colorectal cancer risk in a large population of 18,509 individuals.

IMPACT

These results suggest that in genome-wide analysis common genetic variants do not strongly modify the association between calcium intake and colorectal cancer in European populations.

Identification of susceptibility loci for colorectal cancer in a genome-wide meta-analysis

To identify common variants influencing colorectal cancer (CRC) risk, we performed a meta-analysis of five genome-wide association studies, comprising 5626 cases and 7817 controls of European descent. We conducted replication of top ranked single nucleotide polymorphisms (SNPs) in additional series totalling 14 037 cases and 15 937 controls, identifying a new CRC risk locus at 10q24.2 [rs1035209; odds ratio (OR) = 1.13, P = 4.54 × 10(-11)]. We also performed meta-analysis of our studies, with previously published data, of several recently purported CRC risk loci. We failed to find convincing evidence for a previously reported genome-wide association at rs11903757 (2q32.3). Of the three additional loci for which evidence of an association in Europeans has been previously described we failed to show an association between rs59336 (12q24.21) and CRC risk. However, for the other two SNPs, our analyses demonstrated new, formally significant associations with CRC. These are rs3217810 intronic in CCND2 (12p13.32; OR = 1.19, P = 2.16 × 10(-10)) and rs10911251 near LAMC1 (1q25.3; OR = 1.09, P = 1.75 × 10(-8)). Additionally, we found some evidence to support a relationship between, rs647161, rs2423297 and rs10774214 and CRC risk originally identified in East Asians in our European datasets. Our findings provide further insights into the genetic and biological basis of inherited genetic susceptibility to CRC.

Variation in the association between colorectal cancer susceptibility loci and colorectal polyps by polyp type

We conducted a case-control study of the association between subsets of colorectal polyps, including adenomas and serrated polyps, and single-nucleotide polymorphisms (SNPs) related to colorectal cancer through prior genome-wide association studies (GWAS). Participants were enrollees in the Group Health Cooperative (Seattle, Washington) aged 24-79 years who received a colonoscopy from 1998 to 2007, donated a buccal or blood sample, and completed a structured questionnaire. We performed genotyping of 13 colorectal cancer susceptibility SNPs. Polytomous logistic regression models were used to estimate odds ratios and 95% confidence intervals for associations between polyps and the colorectal cancer risk allele for each SNP under a log-additive model. Analyses included 781 controls, 489 cases with adenoma, 401 cases with serrated polyps, and 188 cases with both polyp types. The following SNPs were associated with advanced adenomas: rs10936599, rs10795668, rs16892766, and rs9929218 (P < 0.05). For nonadvanced adenomas and for serrated polyps overall, only rs961253 was statistically significant (P < 0.05). These associations were in the same directions as those in prior colorectal cancer GWAS. No SNP was significantly associated with hyperplastic polyps, and only rs6983267 was significantly associated with sessile serrated polyps, but this association was opposite of that found in colorectal cancer GWAS. Our results suggest that the association between colorectal cancer susceptibility SNPs and colorectal polyps varies by polyp type.

Gene-environment interaction involving recently identified colorectal cancer susceptibility Loci

BACKGROUND

Genome-wide association studies have identified several single nucleotide polymorphisms (SNPs) that are associated with risk of colorectal cancer. Prior research has evaluated the presence of gene-environment interaction involving the first 10 identified susceptibility loci, but little work has been conducted on interaction involving SNPs at recently identified susceptibility loci, including: rs10911251, rs6691170, rs6687758, rs11903757, rs10936599, rs647161, rs1321311, rs719725, rs1665650, rs3824999, rs7136702, rs11169552, rs59336, rs3217810, rs4925386, and rs2423279.

METHODS

Data on 9,160 cases and 9,280 controls from the Genetics and Epidemiology of Colorectal Cancer Consortium (GECCO) and Colon Cancer Family Registry (CCFR) were used to evaluate the presence of interaction involving the above-listed SNPs and sex, body mass index (BMI), alcohol consumption, smoking, aspirin use, postmenopausal hormone (PMH) use, as well as intake of dietary calcium, dietary fiber, dietary folate, red meat, processed meat, fruit, and vegetables. Interaction was evaluated using a fixed effects meta-analysis of an efficient Empirical Bayes estimator, and permutation was used to account for multiple comparisons.

RESULTS

None of the permutation-adjusted P values reached statistical significance.

CONCLUSIONS

The associations between recently identified genetic susceptibility loci and colorectal cancer are not strongly modified by sex, BMI, alcohol, smoking, aspirin, PMH use, and various dietary factors.

IMPACT

Results suggest no evidence of strong gene-environment interactions involving the recently identified 16 susceptibility loci for colorectal cancer taken one at a time.

Characterisation of familial colorectal cancer Type X, Lynch syndrome, and non-familial colorectal cancer

BACKGROUND

Familial Colorectal Cancer Type X (FCCTX) is defined as individuals with colorectal cancer (CRC) who families meet Amsterdam Criteria-1 (AC1), but whose tumours are DNA-mismatch-repair-proficient, unlike Lynch syndrome (LS). FCCTX does not have an increased risk of extra-colonic cancers. This analysis compares epidemiologic and clinicopathologic features among FCCTX, LS, and 'non-familial' (non-AC1) CRC cases.

METHODS

From the Colon Cancer Family Registry, FCCTX (n=173), LS (n=303), and non-AC1 (n=9603) CRC cases were identified. Questionnaire-based epidemiologic information and CRC pathologic features were compared across case groups using polytomous logistic regression.

RESULTS

Compared with LS, FCCTX cases were less likely to be current (vs never) smokers; have a proximal subsite (vs rectal) tumour; or have mucinous histology, poor differentiation, or tumour-infiltrating lymphocytes. There were no observed differences in co-morbidities or medication usage.

CONCLUSIONS

FCCTX were less likely to be current tobacco users; other exposures were similar between these groups. Histopathologic differences highly suggestive of LS CRCs do not appear to be shared by FCCTX.

Genetic variation in prostaglandin synthesis and related pathways, NSAID use and colorectal cancer risk in the Colon Cancer Family Registry

Although use of non-steroidal anti-inflammatory drugs (NSAIDs) generally decreases colorectal cancer (CRC) risk, inherited genetic variation in inflammatory pathways may alter their potential as preventive agents. We investigated whether variation in prostaglandin synthesis and related pathways influences CRC risk in the Colon Cancer Family Registry by examining associations between 192 single nucleotide polymorphisms (SNPs) and two variable nucleotide tandem repeats (VNTRs) within 17 candidate genes and CRC risk. We further assessed interactions between these polymorphisms and NSAID use on CRC risk. Using a case-unaffected-sibling-control design, this study included 1621 primary invasive CRC cases and 2592 sibling controls among Caucasian men and women aged 18-90. After adjustment for multiple comparisons, two intronic SNPs were associated with rectal cancer risk: rs11571364 in ALOX12 [OR(het/hzv) = 1.87, 95% confidence interval (CI) = 1.19-2.95, P = 0.03] and rs45525634 in PTGER2 (OR(het/hzv) = 0.49, 95% CI = 0.29-0.82, P = 0.03). Additionally, there was an interaction between NSAID use and the intronic SNP rs2920421 in ALOX12 on risk of CRC (P = 0.03); among those with heterozygous genotypes, risk was reduced for current NSAID users compared with never or former users (OR(het) = 0.60, 95% CI = 0.45-0.80), though not among those with homozygous wild-type or variant genotypes. The results of this study suggest that genetic variation in ALOX12 and PTGER2 may affect the risk of rectal cancer. In addition, this study suggests plausible interactions between NSAID use and variants in ALOX12 on CRC risk. These results may aid in the development of genetically targeted cancer prevention strategies with NSAIDs.