Polygenic and multifactorial scores for pancreatic ductal adenocarcinoma risk prediction.

BACKGROUND: Most cases of pancreatic ductal adenocarcinoma (PDAC) are asymptomatic in early stages, and the disease is typically diagnosed in advanced phases, resulting in very high mortality. Tools to identify individuals at high risk of developing PDAC would be useful to improve chances of early detection. OBJECTIVE: We generated a polygenic risk score (PRS) for PDAC risk prediction, combining the effect of known risk SNPs, and carried out an exploratory analysis of a multifactorial score. METHODS: We tested the associations of the individual known risk SNPs on up to 2851 PDAC cases and 4810 controls of European origin from the PANcreatic Disease ReseArch (PANDoRA) consortium. Thirty risk SNPs were included in a PRS, which was computed on the subset of subjects that had 100% call rate, consisting of 839 cases and 2040 controls in PANDoRA and 6420 cases and 4889 controls from the previously published Pancreatic Cancer Cohort Consortium I-III and Pancreatic Cancer Case-Control Consortium genome-wide association studies. Additional exploratory multifactorial scores were constructed by complementing the genetic score with smoking and diabetes. RESULTS: The scores were associated with increased PDAC risk and reached high statistical significance (OR=2.70, 95% CI 1.99 to 3.68, p=2.54×10-10 highest vs lowest quintile of the weighted PRS, and OR=14.37, 95% CI 5.57 to 37.09, p=3.64×10-8, highest vs lowest quintile of the weighted multifactorial score). CONCLUSION: We found a highly significant association between a PRS and PDAC risk, which explains more than individual SNPs and is a step forward in the direction of the construction of a tool for risk stratification in the population.

Mendelian randomisation study of the effects of known and putative risk factors on pancreatic cancer.

BACKGROUND: Observational studies have reported multiple risk factors for pancreatic ductal adenocarcinoma (PDAC). Some are well established, like tobacco smoking, alcohol drinking, obesity and type 2 diabetes, whereas some others are putative, such as allergy and dietary factors. Identifying causal risk factors can help establishing those that can be targeted to contribute to prevent PDAC. OBJECTIVE: We sought to investigate the possible causal effects of established and putative factors on PDAC risk. METHODS: We conducted a two-sample Mendelian randomisation (MR) study using publicly available data for genetic variants associated with the factors of interest, and summary genetic data from genome-wide association studies of the Pancreatic Cancer Cohort Consortium (PanScan) and the Pancreatic Cancer Case-Control Consortium (PanC4), including in total 8769 cases and 7055 controls. Causality was assessed using inverse-variance weighted, MR-Egger regression and weighted median methods, complemented with sensitivity and radial MR analyses. RESULTS: We found evidence for a causal effect of body mass index (BMI) on PDAC risk (OR 1.43, 95% CI 1.20 to 1.71, p=8.43×10-5). Fasting insulin (OR 2.84, 95% CI 1.23 to 6.56, p=0.01), low-density lipoprotein cholesterol (OR 1.16, 95% CI 1.02 to 1.32, p=0.03) and type 2 diabetes (OR 1.09, 95% CI 1.01 to 1.17, p=0.02) were also causally associated with PDAC risk. BMI showed both direct and fasting insulin-mediated causal effects. CONCLUSION: We found strong evidence that BMI is causally associated with PDAC risk, providing support that obesity management may be a potential prevention strategy for reducing pancreatic cancer risk while fasting insulin and type 2 diabetes showed a suggestive association that should be further investigated.

Genetic polymorphisms in the cag pathogenicity island of Helicobacter pylori and risk of stomach cancer and high-grade premalignant gastric lesions.

Helicobacter pylori (Hp) infects the stomach of about half of the human population and is strongly associated with the risk of gastric cancer (GC) and its premalignant precursors. The cag pathogenicity island (cagPAI) is a region of the Hp genome encoding for key molecular machinery involved in the infection process. Following a sequencing study, we selected 50 genetic polymorphisms located in seven cagPAI genes and tested their associations with the risk of advanced gastric premalignant lesions and GC in 1220 subjects from various Latin American populations showing the whole spectrum of phenotypes from gastritis to GC. We found that three polymorphisms of cagA are associated with the risk of advanced gastric premalignant lesions (incomplete intestinal metaplasia [ie, Type 2 and 3] or dysplasia), and that six polymorphisms located in cagA, cagL and cagI were associated with risk of GC. When corrected for multiple testing none of the associations were statistically significant. However, scores built by integrating the individual polymorphisms were significantly associated with the risk of advanced gastric premalignant lesions and GC. These results have the potential of establishing markers for risk stratification in the general population, in view of targeting Hp eradication to high-risk population groups.

Genome-wide association study identifies an early onset pancreatic cancer risk locus.

Early onset pancreatic cancer (EOPC) is a rare disease with a very high mortality rate. Almost nothing is known on the genetic susceptibility of EOPC, therefore, we performed a genome-wide association study (GWAS) to identify novel genetic variants specific for patients diagnosed with pancreatic ductal adenocarcinoma (PDAC) at younger ages. In the first phase, conducted on 821 cases with age of onset ≤60 years, of whom 198 with age of onset ≤50, and 3227 controls from PanScan I-II, we observed four SNPs (rs7155613, rs2328991, rs4891017 and rs12610094) showing an association with EOPC risk (P < 1 × 10-4 ). We replicated these SNPs in the PANcreatic Disease ReseArch (PANDoRA) consortium and used additional in silico data from PanScan III and PanC4. Among these four variants rs2328991 was significant in an independent set of 855 cases with age of onset ≤60 years, of whom 265 with age of onset ≤50, and 4142 controls from the PANDoRA consortium while in the in silico data, we observed no statistically significant association. However, the resulting meta-analysis supported the association (P = 1.15 × 10-4 ). In conclusion, we propose a novel variant rs2328991 to be involved in EOPC risk. Even though it was not possible to find a mechanistic link between the variant and the function, the association is supported by a solid statistical significance obtained in the largest study on EOPC genetics present so far in the literature.

Genetic determinants of telomere length and risk of pancreatic cancer: A PANDoRA study.

Telomere deregulation is a hallmark of cancer. Telomere length measured in lymphocytes (LTL) has been shown to be a risk marker for several cancers. For pancreatic ductal adenocarcinoma (PDAC) consensus is lacking whether risk is associated with long or short telomeres. Mendelian randomization approaches have shown that a score built from SNPs associated with LTL could be used as a robust risk marker. We explored this approach in a large scale study within the PANcreatic Disease ReseArch (PANDoRA) consortium. We analyzed 10 SNPs (ZNF676-rs409627, TERT-rs2736100, CTC1-rs3027234, DHX35-rs6028466, PXK-rs6772228, NAF1-rs7675998, ZNF208-rs8105767, OBFC1-rs9420907, ACYP2-rs11125529 and TERC-rs10936599) alone and combined in a LTL genetic score ("teloscore", which explains 2.2% of the telomere variability) in relation to PDAC risk in 2,374 cases and 4,326 controls. We identified several associations with PDAC risk, among which the strongest were with the TERT-rs2736100 SNP (OR = 1.54; 95%CI 1.35-1.76; p = 1.54 × 10-10 ) and a novel one with the NAF1-rs7675998 SNP (OR = 0.80; 95%CI 0.73-0.88; p = 1.87 × 10-6 , ptrend = 3.27 × 10-7 ). The association of short LTL, measured by the teloscore, with PDAC risk reached genome-wide significance (p = 2.98 × 10-9 for highest vs. lowest quintile; p = 1.82 × 10-10 as a continuous variable). In conclusion, we present a novel genome-wide candidate SNP for PDAC risk (TERT-rs2736100), a completely new signal (NAF1-rs7675998) approaching genome-wide significance and we report a strong association between the teloscore and risk of pancreatic cancer, suggesting that telomeres are a potential risk factor for pancreatic cancer.

Common genetic variants associated with pancreatic adenocarcinoma may also modify risk of pancreatic neuroendocrine neoplasms.

Pancreatic neuroendocrine neoplasms (pNEN) account for less than 5% of all pancreatic neoplasms and genetic association studies on susceptibility to the disease are limited. We sought to identify possible overlap of genetic susceptibility loci between pancreatic ductal adenocarcinoma (PDAC) and pNEN; therefore, PDAC susceptibility variants (n = 23) from Caucasian genome-wide association studies (GWAS) were genotyped in 369 pNEN cases and 3277 controls from the PANcreatic Disease ReseArch (PANDoRA) consortium to evaluate the odds associated with pNEN risk, disease onset and tumor characteristics. Main effect analyses showed four PDAC susceptibility variants-rs9854771, rs1561927, rs9543325 and rs10919791 to be associated with pNEN risk. Subsequently, only associations with rs9543325, rs10919791 and rs1561927 were noteworthy with false positive report probability (FPRP) tests. Stratified analyses considering age at onset (50-year threshold), showed rs2736098, rs16986825 and rs9854771 to be associated with risk of developing pNEN at a younger age. Stratified analyses also showed some single nucleotide polymorphisms to be associated with different degrees of tumor grade, metastatic potential and functionality. Our results identify known GWAS PDAC susceptibility loci, which may also be involved in sporadic pNEN etiology and suggest that some genetic mechanisms governing pathogenesis of these two entities may be similar, with few of these loci being more influential in younger cases or tumor subtypes.

Confirmation of the reduction of hormone replacement therapy-related breast cancer risk for carriers of the HSD17B1_937_G variant.

17ß-hydroxysteroid dehydrogenase type 1 (HSD17B1) plays an important role in the biosynthesis of 17ß-estradiol. The current study aimed at confirming the reduced risk of breast cancer in carriers of the non-synonymous HSD17B1_937_A>G (rs605059) polymorphism who used any hormone replacement therapy (HRT) for 10 years or longer. We performed an independent association study using four breast cancer case-control studies from Australia, Germany, and Sweden. In all, 5,777 cases and 8,189 age-matched controls of European descent were genotyped by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) and TaqMan. Risk estimates were calculated by interaction analysis and main effect analysis adjusted for age and study. Main effect analyses for women using any HRT for 10 years or longer (1,428 cases versus 1,724 controls) revealed a protective effect of the HSD17B1_937_G allele on breast cancer risk (OR 0.86, 95 % CI: 0.73-0.99; p = 0.048). Thus, our previous finding of a protective effect of the HSD17B1_937_G allele on HRT-associated breast cancer risk has now been confirmed both in independent large patient cohorts and a comprehensive pooled analysis supporting the hypothesis that a HSD17B1-mediated decreased conversion of estrone to the more potent 17ß-estradiol may reduce the estrogenic effects, thereby reducing the risk of developing breast cancer during long-term HRT use.

Variations in cag pathogenicity island genes of Helicobacter pylori from Latin American groups may influence neoplastic progression to gastric cancer.

Helicobacter pylori (HP) colonizes the human stomach and induces acute gastritis, peptic ulcer disease, atrophic gastritis, and gastric adenocarcinoma. Increased virulence in HP isolates derives from harboring the cag (cytotoxin-associated genes) pathogenicity island (cagPAI). We analyzed the microvariants in cagPAI genes with the hypothesis that they may play an important role in determining HP virulence. We tested DNAs from cagA positive patients HP isolates; a total of 74 patients with chronic gastritis (CG, N = 37), intestinal metaplasia (IM, N = 21) or gastric cancer (GC, N = 16) from Mexico and Colombia. We selected 520 non-synonymous variants with at least 7.5% frequency in the original sequence outputs or with a minimum of 5 isolates with minor allele. After adjustment for multiple comparisons, no variants were statistically significantly associated with IM or GC. However, 19 non-synonymous showed conventional P-values < 0.05 comparing the frequency of the alleles between the isolates from subjects with gastritis and isolates from subjects with IM or GC; 12 of these showed a significant correlation with the severity of the disease. The present study revealed that several cagPAI genes from Latin American Western HP strains contains a number of non-synonymous variants in relatively high frequencies which could influence on the clinical outcome. However, none of the associations remained statistically significant after adjustment for multiple comparison.

Lack of Association for Reported Endocrine Pancreatic Cancer Risk Loci in the PANDoRA Consortium.

Background: Pancreatic neuroendocrine tumors (PNETs) are rare neoplasms for which very little is known about either environmental or genetic risk factors. Only a handful of association studies have been performed so far, suggesting a small number of risk loci.Methods: To replicate the best findings, we have selected 16 SNPs suggested in previous studies to be relevant in PNET etiogenesis. We genotyped the selected SNPs (rs16944, rs1052536, rs1059293, rs1136410, rs1143634, rs2069762, rs2236302, rs2387632, rs3212961, rs3734299, rs3803258, rs4962081, rs7234941, rs7243091, rs12957119, and rs1800629) in 344 PNET sporadic cases and 2,721 controls in the context of the PANcreatic Disease ReseArch (PANDoRA) consortium.Results: After correction for multiple testing, we did not observe any statistically significant association between the SNPs and PNET risk. We also used three online bioinformatic tools (HaploReg, RegulomeDB, and GTEx) to predict a possible functional role of the SNPs, but we did not observe any clear indication.Conclusions: None of the selected SNPs were convincingly associated with PNET risk in the PANDoRA consortium.Impact: We can exclude a major role of the selected polymorphisms in PNET etiology, and this highlights the need for replication of epidemiologic findings in independent populations, especially in rare diseases such as PNETs. Cancer Epidemiol Biomarkers Prev; 26(8); 1349-51. ©2017 AACR.

Three new pancreatic cancer susceptibility signals identified on chromosomes 1q32.1, 5p15.33 and 8q24.21.

Genome-wide association studies (GWAS) have identified common pancreatic cancer susceptibility variants at 13 chromosomal loci in individuals of European descent. To identify new susceptibility variants, we performed imputation based on 1000 Genomes (1000G) Project data and association analysis using 5,107 case and 8,845 control subjects from 27 cohort and case-control studies that participated in the PanScan I-III GWAS. This analysis, in combination with a two-staged replication in an additional 6,076 case and 7,555 control subjects from the PANcreatic Disease ReseArch (PANDoRA) and Pancreatic Cancer Case-Control (PanC4) Consortia uncovered 3 new pancreatic cancer risk signals marked by single nucleotide polymorphisms (SNPs) rs2816938 at chromosome 1q32.1 (per allele odds ratio (OR) = 1.20, P = 4.88x10 -15), rs10094872 at 8q24.21 (OR = 1.15, P = 3.22x10 -9) and rs35226131 at 5p15.33 (OR = 0.71, P = 1.70x10 -8). These SNPs represent independent risk variants at previously identified pancreatic cancer risk loci on chr1q32.1 ( NR5A2), chr8q24.21 ( MYC) and chr5p15.33 ( CLPTM1L- TERT) as per analyses conditioned on previously reported susceptibility variants. We assessed expression of candidate genes at the three risk loci in histologically normal ( n = 10) and tumor ( n = 8) derived pancreatic tissue samples and observed a marked reduction of NR5A2 expression (chr1q32.1) in the tumors (fold change -7.6, P = 5.7x10 -8). This finding was validated in a second set of paired ( n = 20) histologically normal and tumor derived pancreatic tissue samples (average fold change for three NR5A2 isoforms -31.3 to -95.7, P = 7.5x10 -4-2.0x10 -3). Our study has identified new susceptibility variants independently conferring pancreatic cancer risk that merit functional follow-up to identify target genes and explain the underlying biology.

The UGT1A6_19_GG genotype is a breast cancer risk factor.

Validation of an association between the UGT1A6_19_T>G (rs6759892) polymorphism and overall breast cancer risk. A pilot study included two population-based case-control studies from Germany (MARIE-GENICA). An independent validation study comprised four independent breast cancer case-control studies from Finland (KBCP, OBCS), Germany (BBCC), and Sweden (SASBAC). The pooled analysis included 7418 cases and 8720 controls from all six studies. Participants were of European descent. Genotyping was done by MALDI-TOF MS and statistical analysis was performed by logistic regression adjusted for age and study. The increased overall breast cancer risk for women with the UGT1A6_19_GG genotype which was observed in the pilot study was confirmed in the set of four independent study collections (OR 1.13, 95% CI 1.05-1.22; p = 0.001). The pooled study showed a similar effect (OR 1.09, 95% CI 1.04-1.14; p = 0.001). The risk effect on the basis of allele frequencies was highly significant, the pooled analysis showed an OR of 1.11 (95% CI 1.06-1.16; p = 5.8 × 10(-6)). We confirmed the association of UGT1A6_19_GG with increased overall breast cancer risk and conclude that our result from a well powered multi-stage study adds a novel candidate to the panel of validated breast cancer susceptibility loci.

The pharmacogenomics of sex hormone metabolism: breast cancer risk in menopausal hormone therapy.

With women in western countries spending nearly one-third of their lifetime beyond menopause and a substantial number of these women facing severe menopausal symptoms, the goal of sex hormone pharmacogenomics is to promote the safe use of hormone replacement therapy (HRT). This could be achieved by providing molecular predictors for the upfront stratification of women in need of relief from menopausal symptoms into those with a likely benefit from HRT and those with a contraindication due to an HRT-associated breast cancer risk or other adverse effects. An increasing knowledge base of sex hormone metabolism and its variability, HRT outcomes and breast cancer susceptibility, as well as emerging examples of pharmacogenomic predictors, underscore the potential relevance of genetic variations for HRT outcome. The genes responsible for the metabolism, signaling and action of sex hormones are at the heart of this research; however, pharmacogenomic investigation of their therapeutic effects due to the enormous complexity of the biological pathways involved is still in its infancy. This article discusses the current knowledge, challenges and potential future directions towards the goal of genotype-guided safer HRT use.