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Background Previous genome-wide association studies (GWAS) have identified 42 loci (P < 5 × 10−8) associated with risk of colorectal cancer (CRC). Expanded consortium efforts facilitating the discovery of additional susceptibility loci may capture unexplained familial risk. Methods We conducted a GWAS in European descent CRC cases and control subjects using a discovery–replication design, followed by examination of novel findings in a multiethnic sample (cumulative n = 163 315). In the discovery stage (36 948 case subjects/30 864 control subjects), we identified genetic variants with a minor allele frequency of 1% or greater associated with risk of CRC using logistic regression followed by a fixed-effects inverse variance weighted meta-analysis. All novel independent variants reaching genome-wide statistical significance (two-sided P < 5 × 10−8) were tested for replication in separate European ancestry samples (12 952 case subjects/48 383 control subjects). Next, we examined the generalizability of discovered variants in East Asians, African Americans, and Hispanics (12 085 case subjects/22 083 control subjects). Finally, we examined the contributions of novel risk variants to familial relative risk and examined the prediction capabilities of a polygenic risk score. All statistical tests were two-sided. Results The discovery GWAS identified 11 variants associated with CRC at P < 5 × 10−8, of which nine (at 4q22.2/5p15.33/5p13.1/6p21.31/6p12.1/10q11.23/12q24.21/16q24.1/20q13.13) independently replicated at a P value of less than .05. Multiethnic follow-up supported the generalizability of discovery findings. These results demonstrated a 14.7% increase in familial relative risk explained by common risk alleles from 10.3% (95% confidence interval [CI] = 7.9% to 13.7%; known variants) to 11.9% (95% CI = 9.2% to 15.5%; known and novel variants). A polygenic risk score identified 4.3% of the population at an odds ratio for developing CRC of at least 2.0. Conclusions This study provides insight into the architecture of common genetic variation contributing to CRC etiology and improves risk prediction for individualized screening.

Although genome-wide association studies (GWAS) have separately identified many genetic susceptibility loci for ulcerative colitis (UC), Crohn's disease (CD) and colorectal cancer (CRC), there has been no large-scale examination for pleiotropy, or shared genetic susceptibility, for these conditions. We used logistic regression modeling to examine the associations of 181 UC and CD susceptibility variants previously identified by GWAS with risk of CRC using data from the Genetics and Epidemiology of Colorectal Cancer Consortium and the Colon Cancer Family Registry. We also examined associations of significant variants with clinical and molecular characteristics in a subset of the studies. Among 11794 CRC cases and 14190 controls, rs11676348, the susceptibility single nucleotide polymorphism (SNP) for UC, was significantly associated with reduced risk of CRC (P = 7E-05). The multivariate-adjusted odds ratio of CRC with each copy of the T allele was 0.93 (95% CI 0.89-0.96). The association of the SNP with risk of CRC differed according to mucinous histological features (P heterogeneity = 0.008). In addition, the (T) allele was associated with lower risk of tumors with Crohn's-like reaction but not tumors without such immune infiltrate (P heterogeneity = 0.02) and microsatellite instability-high (MSI-high) but not microsatellite stable or MSI-low tumors (P heterogeneity = 0.03). The minor allele (T) in SNP rs11676348, located downstream from CXCR2 that has been implicated in CRC progression, is associated with a lower risk of CRC, particularly tumors with a mucinous component, Crohn's-like reaction and MSI-high. Our findings offer the promise of risk stratification of inflammatory bowel disease patients for complications such as CRC.

Colorectal cancer is the third most common cancer, and the third most common cause of cancer-related death, among both men and women in the United States. To address this unmet clinical need, ongoing efforts have focused on classifying different subtypes of colorectal cancer, with the goal of identifying therapies with the highest likelihood of success for a given tumor subtype. One marker that has been associated with poor clinical outcome in multiple solid tumor types, including colorectal cancer, is the accumulation of the glycosaminoglycan hyaluronan (HA), which, in preclinical tumor models, increases interstitial fluid pressure, compresses tumor vasculature, and restricts the access of therapeutics. PEGylated recombinant human hyaluronidase PH20 (pegvorhyaluronidase alfa; PEGPH20), which enzymatically degrades HA, is currently being evaluated in combination with existing therapies in clinical trials for HA-accumulating pancreatic, gastric, non-small cell lung, and bile duct cancers. Here, we review the available data for PEGPH20 as published by the authors to evaluate the potential utility of PEGPH20 in treating colorectal cancer. We first studied PEGPH20 in two HA-accumulating murine colon tumor models: CT26 transduced with hyaluronan synthase-3 (HAS3) and MC38 (Charles River Laboratories). In CT26-HAS3 tumors, PEGPH20 monotherapy induced 43% tumor growth inhibition and was associated with tumor blood vessel decompression. In combination with anti-CTLA4 treatment, PEGPH20 further enhanced tumor growth inhibition (79%, p≤0.002 vs anti-CTLA4 alone and PEGPH20 alone). In MC38 tumors, combination of PEGPH20 with anti-PD-L1 treatment significantly increased infiltration of CD8+ T cells (2.8-fold, p Citation Format: Renee Clift, Benjamin J. Thompson, Darin Taverna, Barbara Blouw, Jisook Lee, Curtis B. Thompson, Daniel C. Maneval. Rationale for evaluating PEGylated recombinant human hyaluronidase PH20 (pegvorhyaluronidase alfa; PEGPH20) in patients with hyaluronan (HA)-accumulating colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1743.

Corrigendum: Genome-wide association study of colorectal cancer identifies six new susceptibility loci

El document inclou una pàgina final amb una correcció (corrigendum). Aquesta, per si sola, té el següent DOI: 10.1038/ncomms9739 i es va publicar al mateix vol. 6., Genetic susceptibility to colorectal cancer is caused by rare pathogenic mutations and common genetic variants that contribute to familial risk. Here we report the results of a two-stage association study with 18,299 cases of colorectal cancer and 19,656 controls, with follow-up of the most statistically significant genetic loci in 4,725 cases and 9,969 controls from two Asian consortia. We describe six new susceptibility loci reaching a genome-wide threshold of P

Arachidonate lipoxygenase (ALOX) enzymes metabolize arachidonic acid to generate potent inflammatory mediators and play an important role in inflammation-associated diseases. We investigated associations between colorectal cancer risk and polymorphisms in ALOX5, FLAP, ALOX12, and ALOX15, and their interactions with non-steroidal anti-inflammatory drug (NSAID) use. We genotyped fifty tagSNPs, one candidate SNP, and two functional promoter variable nucleotide tandem repeat (VNTR) polymorphisms in three US population-based case-control studies of colon cancer (1424 cases/1780 controls), rectal cancer (583 cases/775 controls), and colorectal adenomas (485 cases/578 controls). Individuals with variant genotypes of the ALOX5 VNTR had decreased risk of rectal cancer, with the strongest association seen for individuals with one or more alleles of >5 repeats (wildtype=5, OR>5/≥5=0.42, 95% CI 0.20-0.92; p=0.01). Four SNPs in FLAP (rs17239025), ALOX 12 (rs2073438), and ALOX15 (rs4796535 and rs2619112) were associated with rectal cancer risk at p≤0.05. One SNP in FLAP (rs12429692) was associated with adenoma risk. A false discovery rate (FDR) was applied to account for false positives due to multiple testing; the ALOX15 associations were noteworthy at 25% FDR. Colorectal neoplasia risk appeared to be modified by NSAID use in individuals with variant alleles in FLAP and ALOX15. One noteworthy interaction (25% FDR) was observed for rectal cancer. Genetic variability in arachidonate lipoxygenases may affect risk of colorectal neoplasia, particularly for rectal cancer. Additionally, genetic variability in FLAP and ALOX15 may modify the protective effect of NSAID use against colorectal neoplasia.

Background: It is widely accepted that chronic inflammation plays a role in the etiology of colorectal cancer. Using a two-stage design, we examined the associations between colorectal cancer and common variation in 37 key genes in the inflammation and innate immunity pathways. Methods: In the discovery stage, 2,322 discordant sibships (2,535 cases, 3,915 sibling controls) from the Colorectal Cancer Family Registry were genotyped for more than 600 tagSNPs and 99 single-nucleotide polymorphisms (SNP) were selected for further examination based on strength of association. In the second stage, 351 SNPs tagging gene regions covered by the 99 SNPs were tested in 4,783 Multiethnic Cohort subjects (2,153 cases, 2,630 controls). Results: The association between rs9858822 in the PPARG gene and colorectal cancer was statistically significant at the end of the second stage (OR per allele = 1.36, Bonferroni-adjusted P = 0.045), based on the “effective” number of markers in stage II (n = 306). The risk allele C was common (frequency 0.3) in African Americans but rare (frequency < 0.03) in whites, Japanese Americans, Latinos, and Native Hawaiians. No statistically significant heterogeneity of effects across race/ethnicity, body mass index (BMI) levels, regular aspirin use, or pack-years of smoking was detected for this SNP. Suggestive associations were also observed for several SNPs in close vicinity to rs9858822. Conclusions: Our results provide new evidence of association between PPARG variants and colorectal cancer risk. Impact: Further replication in independent samples is warranted. Cancer Epidemiol Biomarkers Prev; 22(11); 2094–101. ©2013 AACR.

Introduction: 5-Lipoxygenase-activating protein (FLAP) binds to arachidonic acid (AA) and activates arachidonate 5-lipoxygenase (ALOX5). ALOX5 is upregulated in colon cancer and is involved in the synthesis of leukotriene A4, which plays an important role in immunity and inflammation. ALOX5 also competes with the prostaglandin H synthases PTGS1 and PTGS2, which convert AA into prostaglandins. NSAIDs reduce the risk of colorectal neoplasia and inhibit PTGS1 and PTGS2. We investigated associations between ALOX5 and FLAP and risk of colorectal neoplasia, as well as potential NSAID interactions in three independent study populations that capture the range of colorectal carcinogenesis by including both adenoma and cancer cases. Methods: A linkage-disequilibrium (LD)-based tagSNP selection algorithm (r2=0.90, MAF=4%) identified 32 tagSNPs in FLAP, representing common genetic variation in Europeans. ALOX5 lacked resequencing data, and we were only able to look at candidate polymorphisms. We used an identical Illumina platform to investigate FLAP SNPs and 1 ALOX5 candidate SNP in three US population-based case-control studies of colon cancer (1424 cases/1780 controls), rectal cancer (583 cases/775 controls), and colorectal adenomas (485 cases/578 controls). VNTR polymorphisms in both genes were also genotyped. Multiple logistic regression analysis was used, adjusting for age, sex, center and restricted to Caucasians (>90% of all study participants). A p value < 0.05 without multiple comparison adjustment was considered statistically significant. Results: The variant ALOX5 allele of rs4986832 G>A showed a significant trend towards decreased risk of rectal cancer (ORhzv=0.65; 95% CI 0.43-0.98; p-trend=0.04). For FLAP, several SNPs showed increased risk of colorectal neoplasia across all three studies, with the strongest associations for: rs12429692 A>T ORhzv=2.05, 95% CI 1.20-3.53 in adenoma (global p=0.01); rs17239025 G>C ORhet/hzv=1.43, 95% CI 1.01-2.04 in rectal cancer (global p=0.05, p-trend=0.04); rs17222919 A>C ORhzv=1.55, 95% CI 1.00-2.42 in rectal cancer (p-trend=0.05). The inverse association with NSAID use was stronger among those with the wildtype genotype for rs9551960 A>G (rectal cancer p-interaction=0.05) and rs17239025 G>C (colon cancer p-int=0.02), whereas those with variant genotypes had greater NSAID risk reduction of rectal cancer for rs9315053 A>C (p-int=0.03), rs9508832 G>A (p-int=0.02), and rs9506352 G>A (p-int=0.04). Conclusion: We show evidence that genetic variability in ALOX5 and FLAP may affect risk of colorectal neoplasia. These results suggest that, in ALOX5, rs4986832 is associated with a decreased risk of rectal cancer, whereas FLAP SNPs rs12429692, rs17239025 and rs17222919 increase colorectal neoplasia risk. Additionally, we provide evidence that genetic variability in FLAP may modify the protective association of NSAID use against colorectal neoplasia. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3761. doi:10.1158/1538-7445.AM2011-3761

Introduction: Arachidonate lipoxygenase (ALOX) enzymes generate potent inflammatory mediators via the metabolism of arachidonic acid. Genetic polymorphisms in the lipoxygenase gene family have been implicated in cancer and inflammatory diseases such as asthma, bone loss, and atherosclerosis. NSAIDs, which reduce colorectal cancer risk, induce apoptosis in colon cancer cells via upregulation of ALOX15. We hypothesize that polymorphisms in lipoxygenases ALOX12 and ALOX15 may influence colorectal neoplasia risk and protective NSAIDs effects. Methods: A linkage-disequilibrium (LD)-based tagSNP-selection algorithm (r2=0.90, MAF=4%) identified tagSNPs in ALOX12 and ALOX15 representing common genetic variation in Europeans. We genotyped 17 SNPs in ALOX12 and 21 SNPs in ALOX15 in three independent study populations that capture the range of colorectal carcinogenesis by including adenoma, colon, and rectal cancer cases. We investigated these SNPs in relation to colorectal neoplasia risk and potential interactions with NSAID use in three US population-based case-control studies of colon cancer (n=1424/1780 cases/controls), rectal cancer (n=583/775), and colorectal adenoma (n=485/578). Multiple logistic regression analysis was used, adjusting for age, sex, and study site, and restricted to Caucasians (>90% of all study participants). A p value < 0.05 without multiple comparison adjustment was considered statistically significant. Results: In ALOX12, rs11571364 was associated with a modestly increased risk of colon cancer among variant allele carriers (OR: 1.23, 95% CI: 1.01-1.51). A risk increase was also seen in rectal cancer, but was not statistically significant (OR: 1.26, 95% CI: 0.92-1.71). The homozygous variant genotype of another SNP in ALOX12 showed a possible reduced risk of rectal cancer (rs2073438, OR: 0.66, 95% CI: 0.42-1.04), but not colon cancer or adenomas. No significant interactions between SNPs in ALOX12 and NSAID use were observed in any of the three studies. In ALOX15, rs2619112 showed a suggested increase in rectal cancer risk. However, the risk was more elevated among those with a heterozygous genotype (OR: 1.37; 95% CI: 1.06-1.77) than among those with a homozygous variant genotype (OR: 1.13, 95% CI: 0.83-1.55). We detected a significant interaction between this SNP and NSAID use. Among NSAID non-users, the homozygous genotype was associated with increased rectal cancer risk (OR: 1.24). Among NSAID users, the homozygous wildtype and homozygous variant genotypes were associated with decreased risk, but there was no association among heterozygous NSAID users (p-interaction=0.04). Conclusion: Polymorphisms in ALOX12 and ALOX15 are associated with risk of rectal and colon cancer, but not colorectal adenomas. An ALOX15 SNP previously associated with bone mineral density levels and coronary artery disease risk was associated with rectal cancer risk and showed possible interaction with NSAID use. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3756. doi:10.1158/1538-7445.AM2011-3756

Introduction: Glutathione peroxidases (GPXs) are selenium-dependent enzymes that scavenge hydroperoxides linked to oxidative stress, prostaglandin synthesis, inflammation and proliferation. Because these processes are important in carcinogenesis, we hypothesized that genetic variability in the GPXs may influence colorectal neoplasia risk. We investigated candidate polymorphisms and tagSNPs in GPX1-4 in relation to colorectal neoplasia in three independent study populations capturing the range of colorectal carcinogenesis. Methods: A linkage-disequilibrium (LD)-based tagSNP selection algorithm (r2=0.90, MAF=4%) identified 24 tagSNPs, including the candidates (GPX1 P200L and GPX4 2573 C>T), representing common genetic variation in Europeans. We used an identical Illumina platform to investigate GPX SNPs in three US population-based case-control studies of colon cancer (1424 cases/1780 controls), rectal cancer (583 cases/775 controls), and colorectal adenomas (485 cases/578 controls). For gene-level associations, we conducted principal components analysis (PCA). Multiple logistic regression was used for single SNPs, adjusting for age, sex, and study center, restricted to Caucasians (>90% of all study populations). Results: In PCA, GPX3 was significant for rectal cancer at p=0.03. Without correction for multiple testing, five polymorphisms in GPX2 and GPX3 were associated with significant differences in rectal cancer risk at α=0.05 (see Table). GPX3 rs8177406 also reduced risk in rectal polyps. The candidate GPX1 P200L showed a marginally increased risk for LP/LL vs. PP (1.22, 0.98-1.52, p=0.06). No other SNPs in GPX1-4 showed significant associations for rectal cancer or adenomas. No associations were observed for colon cancer. Conclusion: These data provide evidence that genetic variability in GPX2 and GPX3 contributes to risk of rectal cancer but not of colon cancer and thus provide additional support for unique etiological mechanisms for colon and rectal cancer.Table.Selected tagSNPs in GPX1, GPX2 and GPX3 and risk of rectal cancer, adjusted for age, sex, and study center*SNPGenotypeCasesControlsOR95%CIp (2df)p-trendGPX1rs105045**CC252367 2834 C>T, P200LCT or TT3013601.220.981.520.06NAGPX2rs2277502**GG4595741.00.. 2834 G>AGA or AA1141890.770.600.990.04NA rs4902347**GG4565741.00.. 1756 G>AGA or AA1141880.780.601.000.05NAGPX3rs3828599CC3404091.00.. 1580 C->TCT2142980.850.681.07 TT29660.520.330.830.010.01 rs736775CC2372821.00 9133 C->TCT2753540.910.721.15 TT701380.590.420.830.010.01 rs8177447CC4135001.00 7241 C->TCT1552350.790.621.01 TT14350.480.260.910.020.01* r2 < 0.70, except rs2277502 and rs4902347 (r2 > 0.90)** Dominant model is shown because there were 10 or fewer subjects with the homozygous variant model Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 933.

Introduction: Pancreatic phospholipase A2 (also known as PLA2G1B or PLA2A) catalyzes the release of fatty acids from dietary phospholipids for adsorption in the small intestine. Some of the polyunsaturated fatty acids removed from the intestinal lumen are precursors to eicosanoids, which are linked to inflammation, cell proliferation and colorectal carcinogenesis. We suspect that genetic variation at the PLA2A locus might affect colorectal neoplasia and thus we evaluated the association of PLA2A tagSNPs with colorectal neoplasia risk in three independent study populations capturing the range of colorectal carcinogenesis. Methods: A linkage-disequilibrium (LD)-based tagSNP selection algorithm (r2=0.90, MAF=4%) identified 3 tagSNPs in PLA2A. We genotyped these SNPs on the same Illumina platform in 3 US population-based case-control studies of colon cancer (1424 cases/1780 controls), rectal cancer (583 cases/775 controls), and colorectal adenomas (485 cases/578 controls). LD was calculated among Caucasian controls for each study. For gene-level associations, we conducted principal components analysis (PCA) and haplotype analysis. Multiple logistic regression was used for single SNPs, adjusting for age, sex, and study center, restricted to Caucasians (>90% of all study populations). Results: Two PLA2A variants were statistically significantly associated with reduced risk of rectal cancer (rs5637, 3702G>A Ser98Ser, p-trend = 0.03 and rs9657930, 1593C>T p-trend = 0.01, see table). Linkage disequilibrium between the SNPs was modest (r2 Conclusion: The results suggest that genetic variability in PLA2A affects susceptibility to rectal but not colon cancer. Additional observational and functional follow-up studies are needed.Table.Selected tagSNPs in PLA2A and risk of rectal cancer, adjusted for age, sex, and study centerSNPGenotypeCasesControlsOR95%CIp (2df)p-trendrs56373702 G>AGG4285361.00.. Ser98SerGA1472150.850.661.08 AA8230.430.190.980.060.03 rs9657930CC4886141.00.. 1593 C>TCT891480.750.561.00 TT3100.390.111.430.050.01 rs2070873GG4365741.00.. 3027 G>TGT1391811.000.781.29 TT6190.420.171.060.150.36Principal component analysis p= 0.02 Note: This abstract was not presented at the AACR 101st Annual Meeting 2010 because the presenter was unable to attend. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 934.

First results from genome-wide association studies (GWAS) have demonstrated considerable success in identifying genetic variants associated with colorectal cancer (CRC). To date, 10 CRC susceptibility loci have been identified. However, these marginal single nucleotide polymorphism (SNP) associations explain only ∼6% of the heritable variation underlying CRC risk. We employed a pathway-based approach using our recently developed Gene-set Ridge Regression in Association Studies (GRASS) method to assess whether sets of functionally related genes are enriched for SNPs associated with colon cancer risk. We used GWAS data from three studies: The Women's Health Initiative (WHI; 483 cases and 530 controls); the Prostate, Lung, Colon and Ovarian Cancer Screening Trial (PLCO; 546 cases and 1177 controls); and the Diet, Activity and Lifestyle population-based case-control study (DALS; 698 cases and 719 controls). Samples were genotyped on Illumina HumanHap 300K + 240K, 550K or 610K platforms. After applying stringent quality control criteria, our final analysis included 392,361 SNPs. We used genomic partition to assign SNPs to nearby genes and defined pathways using the Kyoto Encyclopedia of Genes and Genomes (KEGG) database. We restricted our analysis to 170 pathways with 10 or more genes (range 10-253 genes). Our GRASS method uses eigenSNPs derived from principal components analysis within each gene. Regularized regression is performed for each pathway, using a novel group ridge penalty function. The penalty function results in selection of the most representative eigenSNPs within genes while assessing the association of all the genes, within a pathway, with disease risk. Permutations are used to standardize the test statistics and obtain p-values. The false discovery rate (FDR) was calculated using the Benjamini-Hochberg method. We analyzed WHI, PLCO and DALS separately, adjusting for age, sex, and genetic ancestry derived from principal components analysis, and performed a meta-analysis to combine the results. Five pathways were significant at a p-value cutoff of 0.05. The top pathway, the transforming growth factor beta (TGF-beta) signaling pathway (p-value=0.009), also met a FDR cutoff of 20%. This pathway remained significant (p=0.014) after excluding the known CRC susceptibility loci and all SNPs with linkage disequilibrium r2>0.2 with those 10 loci. The top genes in the pathway were TFGB1, SMAD4, FST, TFGB2, INHBA, PITX2, BMPR2 and PP2R2B (all p Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4733.

Proceedings: AACR 101st Annual Meeting 2010‐‐ Apr 17‐21, 2010; Washington, DC Introduction: Nonsteroidal anti-inflammatory drugs (NSAIDs) reduce risk of colorectal adenomas and cancer. NSAIDs, including aspirin, target the prostaglandin H synthases, COX-1 and COX-2, which convert arachidonic acid into prostaglandins. We examined tagSNPs and candidate polymorphisms in COX-1 and COX-2 in relation to colorectal neoplasia risk and potential interactions with NSAID use. Methods: A linkage-disequilibrium (LD)-based tagSNP-selection algorithm (r2=0.90, MAF=4%) identified tagSNPs in PTGS1 (COX-1) and PTGS2 (COX-2) representative of common genetic variation in Europeans. Including candidate polymorphisms, we genotyped 18 SNPs in PTGS1 and 17 SNPs in PTGS2. SNPs were genotyped on the same Illumina platform in three independent study populations that capture the range of colorectal carcinogenesis by including adenoma and cancer cases. We investigated these SNPs in relation to the risk of colorectal neoplasia and potential interactions with NSAID use in three US population-based case-control studies of colon cancer (n=1424) vs. controls (n=1780), rectal cancer (n=583) vs. controls (n=775), and colorectal adenoma (n=485) vs. controls (n=578). For single SNP associations, multiple logistic regression analysis was used, adjusting for age, sex, center and restricted to Caucasians (>90% of all study populations). No correction was made for multiple testing. Results: There were no main associations with PTGS1 tagSNPs or candidate polymorphisms (R8W, P17L and L237M) and colorectal neoplasia risk. Although not statistically significant, the L15-L16 deletion allele showed a trend towards increased risk for both colon and rectal cancer, consistent with the previously reported increased adenoma risk. In PTGS2, a rare 5′ tagSNP (rs4648250, −1877A>G, MAF=1%) was associated with a marginally decreased risk of both rectal (OR: 0.24, 95% CI: 0.05-1.08) and colon cancer (OR: 0.63, 95% CI: 0.36-1.10). NSAID use is known to reduce the risk of colorectal neoplasia and all three studies have shown the same protective effect in previous analyses. Interactions between genotypes and NSAID use essentially fell into one of two general categories: a) Individuals with the variant allele lost the protective effect of NSAID use (PTGS1 rs10306110-G, rectal p-interaction=0.02, adenoma p-int=0.08; PTGS2 [rs689466][1]-G, rectal p-int=0.03, colon p-int=0.18; rs20424-G, colon p-int=0.05; [rs689469][2]-A, colon p-int=0.03, rectal p-int=0.09).); and b) Individuals with the variant allele showed stronger protection with by NSAIDs than individuals with the wildtype genotype (PTGS1 rs6478565-G, rs10306135-T, rs10306164-G, rectal p-int=0.01-0.02). Conclusion: These data suggest that a rare 5′ SNP in PTGS2 may predict risk of colorectal cancer and provide further evidence that genetic variability in PTGS1 and PTGS2 may modify the protective association between NSAID and colorectal neoplasia risk, especially for rectal cancer. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 5710. [1]: /lookup/external-ref?link_type=GEN&access_num=rs689466&atom=%2Fcanres%2F70%2F8_Supplement%2F5710.atom [2]: /lookup/external-ref?link_type=GEN&access_num=rs689469&atom=%2Fcanres%2F70%2F8_Supplement%2F5710.atom

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&nbsp