Genome-wide association studies and Mendelian randomization analyses provide insights into the causes of early-onset colorectal cancer.

BACKGROUND: The incidence of early-onset colorectal cancer (EOCRC; diagnosed <50 years of age) is rising globally; however, the causes underlying this trend are largely unknown. CRC has strong genetic and environmental determinants, yet common genetic variants and causal modifiable risk factors underlying EOCRC are unknown. We conducted the first EOCRC-specific genome-wide association study (GWAS) and Mendelian randomization (MR) analyses to explore germline genetic and causal modifiable risk factors associated with EOCRC. PATIENTS AND METHODS: We conducted a GWAS meta-analysis of 6176 EOCRC cases and 65 829 controls from the Genetics and Epidemiology of Colorectal Cancer Consortium (GECCO), the Colorectal Transdisciplinary Study (CORECT), the Colon Cancer Family Registry (CCFR), and the UK Biobank. We then used the EOCRC GWAS to investigate 28 modifiable risk factors using two-sample MR. RESULTS: We found two novel risk loci for EOCRC at 1p34.1 and 4p15.33, which were not previously associated with CRC risk. We identified a deleterious coding variant (rs36053993, G396D) at polyposis-associated DNA repair gene MUTYH (odds ratio 1.80, 95% confidence interval 1.47-2.22) but show that most of the common genetic susceptibility was from noncoding signals enriched in epigenetic markers present in gastrointestinal tract cells. We identified new EOCRC-susceptibility genes, and in addition to pathways such as transforming growth factor (TGF) ß, suppressor of Mothers Against Decapentaplegic (SMAD), bone morphogenetic protein (BMP) and phosphatidylinositol kinase (PI3K) signaling, our study highlights a role for insulin signaling and immune/infection-related pathways in EOCRC. In our MR analyses, we found novel evidence of probable causal associations for higher levels of body size and metabolic factors-such as body fat percentage, waist circumference, waist-to-hip ratio, basal metabolic rate, and fasting insulin-higher alcohol drinking, and lower education attainment with increased EOCRC risk. CONCLUSIONS: Our novel findings indicate inherited susceptibility to EOCRC and suggest modifiable lifestyle and metabolic targets that could also be used to risk-stratify individuals for personalized screening strategies or other interventions.

Insulin-like growth factor-1, insulin-like growth factor-binding protein-3, and breast cancer risk: observational and Mendelian randomization analyses with ∼430 000 women.

BACKGROUND: Epidemiological evidence supports a positive association between circulating insulin-like growth factor-1 (IGF-1) concentrations and breast cancer risk, but both the magnitude and causality of this relationship are uncertain. We conducted observational analyses with adjustment for regression dilution bias, and Mendelian randomization (MR) analyses allowed for causal inference. PATIENTS AND METHODS: We investigated the associations between circulating IGF-1 concentrations and incident breast cancer risk in 206 263 women in the UK Biobank. Multivariable hazard ratios (HRs) and 95% confidence intervals (CI) were estimated using Cox proportional hazards models. HRs were corrected for regression dilution using repeat IGF-1 measures available in a subsample of 6711 women. For the MR analyses, genetic variants associated with circulating IGF-1 and IGF-binding protein-3 (IGFBP-3) levels were identified and their association with breast cancer was examined with two-sample MR methods using genome-wide data from 122 977 cases and 105 974 controls. RESULTS: In the UK Biobank, after a median follow-up of 7.1 years, 4360 incident breast cancer cases occurred. In the multivariable-adjusted models corrected for regression dilution, higher IGF-1 concentrations were associated with a greater risk of breast cancer (HR per 5 nmol/l increment of IGF-1 = 1.11, 95% CI = 1.07-1.16). Similar positive associations were found by follow-up time, menopausal status, body mass index, and other risk factors. In the MR analyses, a 5 nmol/l increment in genetically-predicted IGF-1 concentration was associated with a greater breast cancer risk (odds ratio = 1.05, 95% CI = 1.01-1.10; P = 0.02), with a similar effect estimate for estrogen-positive (ER+) tumours, but no effect found for estrogen-negative (ER-) tumours. Genetically-predicted IGFBP-3 concentrations were not associated with breast cancer risk (odds ratio per 1-standard deviation increment = 1.00, 95% CI = 0.97-1.04; P = 0.98). CONCLUSION: Our results support a probable causal relationship between circulating IGF-1 concentrations and breast cancer, suggesting that interventions targeting the IGF pathway may be beneficial in preventing breast tumorigenesis.

Environment-wide association study to comprehensively test and validate associations between nutrition and lifestyle factors and testosterone deficiency: NHANES 1988-1994 and 1999-2004.

PURPOSE: Testosterone (T) plays an important role in men's health and its deficiency is linked with poorer health. However, the role of nutritional and lifestyle factors in T regulation and production remains unclear. The objectives are to comprehensively test the cross-sectional associations of nutritional and lifestyle factors with T deficiency and to validate the associations in the NHANES survey. METHODS: We performed weighted multivariable logistic regression analysis to examine the association of 173 nutritional and lifestyle factors with T deficiency (total testosterone ≤ 3.5 ng/mL) in NHANES III as the discovery set (mean age 41). We controlled for multiple comparisons with a false discovery rate (FDR) < 5% and replicated in NHANES 1999-2004 (mean age 44). RESULTS: We identified seven nutritional factors as being inversely associated with T deficiency in NHANES 1999-2004, namely dietary intake of vitamin A, protein, saturated fatty acids, monounsaturated fatty acids, total fats, saturated fatty acid 16:0, and phosphorus. In a multivariable model, only vitamin A intake remained significantly associated with T deficiency (OR 0.97, 95% CI 0.94-0.99). Principal component analysis suggested that the two principal components, (1) dietary fats, protein, and phosphorous and (2) total vitamin A, may be associated with T deficiency. CONCLUSION: Our systematic evaluation provided new insight into the modifiable factors that could play a role in the regulation of T production. This study has the potential to contribute to the current body of literature which seeks to formulate a clinical definition of T deficiency after taking into account nutritional and lifestyle factors.

Dietary intake of advanced glycation end products (AGEs) and changes in body weight in European adults.

PURPOSE: Advanced glycation end products (AGEs) can be formed in foods by the reaction of reducing sugars with proteins, and have been shown to induce insulin resistance and obesity in experimental studies. We examined the association between dietary AGEs intake and changes in body weight in adults over an average of 5 years of follow-up. METHODS: A total of 255,170 participants aged 25-70 years were recruited in ten European countries (1992-2000) in the PANACEA study (Physical Activity, Nutrition, Alcohol, Cessation of smoking, Eating out of home in relation to Anthropometry), a sub-cohort of the EPIC (European Prospective Investigation into Cancer and Nutrition). Body weight was measured at recruitment and self-reported between 2 and 11 years later depending on the study center. A reference database for AGEs was used containing UPLC-MS/MS-measured Nε-(carboxymethyl)-lysine (CML), Nε-(1-carboxyethyl)-lysine (CEL), and Nδ-(5-hydro-5-methyl-4-imidazolon-2-yl)-ornithine (MG-H1) in 200 common European foods. This reference database was matched to foods and decomposed recipes obtained from country-specific validated dietary questionnaires in EPIC and intake levels of CEL, CML, and MG-H1 were estimated. Associations between dietary AGEs intake and body weight change were estimated separately for each of the three AGEs using multilevel mixed linear regression models with center as random effect and dietary AGEs intake and relevant confounders as fixed effects. RESULTS: A one-SD increment in CEL intake was associated with 0.111 kg (95% CI 0.087-0.135) additional weight gain over 5 years. The corresponding additional weight gain for CML and MG-H1 was 0.065 kg (0.041-0.089) and 0.034 kg (0.012, 0.057), respectively. The top six food groups contributing to AGEs intake, with varying proportions across the AGEs, were cereals/cereal products, meat/processed meat, cakes/biscuits, dairy, sugar and confectionary, and fish/shellfish. CONCLUSION: In this study of European adults, higher intakes of AGEs were associated with marginally greater weight gain over an average of 5 years of follow-up.

The role of plasma microseminoprotein-beta in prostate cancer: an observational nested case-control and Mendelian randomization study in the European prospective investigation into cancer and nutrition.

BACKGROUND: Microseminoprotein-beta (MSP), a protein secreted by the prostate epithelium, may have a protective role in the development of prostate cancer. The only previous prospective study found a 2% reduced prostate cancer risk per unit increase in MSP. This work investigates the association of MSP with prostate cancer risk using observational and Mendelian randomization (MR) methods. PATIENTS AND METHODS: A nested case-control study was conducted with the European Prospective Investigation into Cancer and Nutrition (EPIC) with 1871 cases and 1871 matched controls. Conditional logistic regression analysis was used to investigate the association of pre-diagnostic circulating MSP with risk of incident prostate cancer overall and by tumour subtype. EPIC-derived estimates were combined with published data to calculate an MR estimate using two-sample inverse-variance method. RESULTS: Plasma MSP concentrations were inversely associated with prostate cancer risk after adjusting for total prostate-specific antigen concentration [odds ratio (OR) highest versus lowest fourth of MSP = 0.65, 95% confidence interval (CI) 0.51-0.84, Ptrend = 0.001]. No heterogeneity in this association was observed by tumour stage or histological grade. Plasma MSP concentrations were 66% lower in rs10993994 TT compared with CC homozygotes (per allele difference in MSP: 6.09 ng/ml, 95% CI 5.56-6.61, r2=0.42). MR analyses supported a potentially causal protective association of MSP with prostate cancer risk (OR per 1 ng/ml increase in MSP for MR: 0.96, 95% CI 0.95-0.97 versus EPIC observational: 0.98, 95% CI 0.97-0.99). Limitations include lack of complete tumour subtype information and more complete information on the biological function of MSP. CONCLUSIONS: In this large prospective European study and using MR analyses, men with high circulating MSP concentration have a lower risk of prostate cancer. MSP may play a causally protective role in prostate cancer.

Double trouble: Co-occurrence of testosterone deficiency and body fatness associated with all-cause mortality in US men.

BACKGROUND: Testosterone deficiency (TD, total testosterone ≤350 ng/dL [12.15 nmol L-1 ]) and obesity epidemic are growing in parallel in the United States. Yet, the sequelae of TD and obesity on the risk of mortality remain unclear. OBJECTIVE: To investigate whether the co-occurrence of TD and overall obesity (body mass index ≥30 kg/m2 ), and abdominal obesity (waist circumference ≥102 cm), is associated with a risk of all-cause mortality in American men. DESIGN: The data were obtained from the NHANES 1999-2004 and the Linked Mortality File (December 31, 2011). A total of 948 participants aged ≥20 years old with endogenous sex hormones and adiposity measurements data were included in this study. RESULTS: Over a median of 9.5 years of follow-up, 142 men died of any cause in this cohort. Multivariable analysis showed a 2.60 fold increased risk of death among men with TD compared with men without TD (Hazard Ratio [HR] = 2.60; 95% confidence interval [CI] = 1.20-5.80). No evidence for interaction between TD and overall or abdominal obesity with risk of death (Pinteraction ≥ .80). However, only after comparing men with TD and abdominal obesity with men without TD and no abdominal obesity, we found a 3.30 fold increased risk of death (HR = 3.30, 95% CI = 1.21-8.71). CONCLUSION: Men with co-occurrence of TD and abdominal obesity have a higher risk of mortality. The effect of co-occurrence of TD and abdominal obesity should be further explored with a larger and longer follow-up time study.

Prevalence of vitamin D deficiency and association with metabolic syndrome in a Qatari population.

OBJECTIVES: Despite long hours of sunlight in Qatar and other regions of the Middle East, vitamin D deficiency has been rising. In parallel, the prevalence of metabolic syndrome has also been increasing in Qatar. Vitamin D levels have been associated with metabolic syndrome but the data are inconsistent and no studies have addressed these inter-relationships in a Middle Eastern population where the prevalence of these conditions is high. The objective is to investigate the prevalence of vitamin D deficiency and its association with metabolic syndrome and its components in the Qatar Biobank population. METHODS: A cross-sectional study of 1205 participants (702 women and 503 men) from the Qatar Biobank, comprising Qataris and non-Qataris between the ages of 18 and 80 years, was used to perform multivariate linear regression analyses to examine the association between metabolic syndrome and prevalence of vitamin D deficiency (defined as <20 ng ml-1 serum vitamin D levels) adjusting for age, sex, ethnicity, season of blood collection, physical activity and education. Odds ratios and 95% confidence intervals were calculated for all analyses. RESULTS: Approximately 64% of participants were vitamin D deficient (<20 ng ml-1) with more men being deficient (68.6%) than women (61.3%). Serum vitamin D was 8% lower in individuals with metabolic syndrome (RR: 0.92, 95%CI: 0.87-0.98, P-value: 0.01) compared to individuals without metabolic syndrome. Waist circumference and HDL as well as high triglyceride levels were also significantly positively associated with vitamin D deficiency. No association was found between the other components of metabolic syndrome or diabetes and the presence of vitamin D deficiency. CONCLUSIONS: Vitamin D deficiency is prevalent in this Qatari population. Presence of metabolic syndrome was associated with presence of vitamin D deficiency. Future prospective studies need to be conducted to investigate the potential for causality.

Investigating nutrition and lifestyle factors as determinants of abdominal obesity: an environment-wide study.

BACKGROUND: The increasing global trends in obesity and its associated burden of disease indicate a need to identify modifiable determinants of obesity. METHODS: A total of 182 nutrition and lifestyles factors were investigated in relation to abdominal obesity among 7,403 male and 8,328 female participants of the Third U.S. National Health and Examination Survey (NHANES III). We used the first phase (1988-1991) of the NHANES III to identify factors with a false discovery rate (FDR) of <5%. Of these, we tentatively replicated our findings in the second phase (1992-1994) of the survey. Principal component analysis was performed to identify unobserved factors underlying the association between validated factors and abdominal obesity, defined as waist circumference >88 cm for women and >102 cm for men. RESULTS: We found five tentatively replicated factors showing significant associations with abdominal obesity in men: serum α-carotene, ß-carotene, serum ß-cryptoxanthin, serum vitamin D and vigorous physical activity. In women, 7 factors were identified: serum α-carotene, ß-carotene, serum ß-cryptoxanthin, serum vitamin C, serum vitamin D, vigorous physical activity and aspartame intake. In contrast to the other factors which showed inverse associations with abdominal obesity, aspartame intake displayed a positive relationship with this outcome (OR: 1.18, 95% CI: 1.10-1.26 for each log increase in aspartame intake in women). Principal component analysis suggested three principal components underlying such associations, each comprising: (1) serum antioxidants; (2) serum vitamin D and vigorous physical activity; and (3) aspartame intake. All three principal components also displayed significant associations with abdominal obesity. CONCLUSION: Our observational investigation that systematically investigates multiple modifiable factors simultaneously has enabled the creation of data-driven hypotheses regarding the possible role of determinants of abdominal obesity and has identified potential avenues for mechanistic investigations to clarify suitable targets of intervention.

Association of variants in genes related to the immune response and obesity with BPH in CLUE II.

BACKGROUND: Chronic inflammation and obesity may contribute to the genesis or progression of BPH and BPH-associated lower urinary tract symptoms (LUTS). The influence of variants in genes related to these states on BPH has not been studied extensively. Thus, we evaluated the association of 17 single-nucleotide polymorphisms (SNPs) in immune response genes (IL1B, IL6, IL8, IL10, TNF, CRP, TLR4 and RNASEL) and genes involved in obesity, including insulin regulation (LEP, ADIPOQ, PPARG and TCF7L2), with BPH. METHODS: BPH cases (N = 568) and age-frequency matched controls (N=568) were selected from among adult male CLUE II cohort participants who responded in 2000 to a mailed questionnaire. BPH was defined as BPH surgery, use of BPH medications or symptomatic BPH (American Urological Association Symptom Index Score ⩾ 15). Controls were men who had not had BPH surgery, did not use BPH medications and whose symptom score was ⩽ 7. Age-adjusted odds ratios (ORs) and 95% confidence intervals (CIs) were estimated using logistic regression. RESULTS: None of the candidate SNPs was statistically significantly associated with BPH. However, we could not rule out possible weak associations for CRP rs1205 (1082C>T), ADIPOQ rs1501299 (276C>A), PPARG rs1801282 (-49C>G) and TCF7L2 rs7903146 (47833T>C). After summing risk alleles, men with ⩾ 4 had an increased BPH risk compared with those with ⩽ 1 (OR, 1.78; 95% CI, 1.10-2.89; P(trend) = 0.006). CONCLUSIONS: SNPs in genes related to immune response and obesity, especially in combination, may be associated with BPH.

Association between endogenous sex steroid hormones and inflammatory biomarkers in US men.

Sex steroid hormones and inflammatory biomarkers are both associated with the development and progression of chronic diseases, but their interrelationship is relatively uncharacterized. We examined the association of sex hormones and sex hormone-binding globulin (SHBG) with biomarkers of inflammation, C-reactive protein (CRP) and white blood cell (WBC) count. The study included data from 809 adult men in the National Health and Nutrition Examination Survey 1999-2004. Geometric means and 95% confidence intervals were estimated separately for CRP and WBC concentrations by sex steroid hormones and SHBG using weighted linear regression models. Higher concentrations of total (slope per one quintile in concentration, -0.18; p-trend, 0.001) and calculated free (slope, -0.13; p-trend, 0.03) testosterone were statistically significantly associated with lower concentrations of CRP, but not with WBC count. Men in the bottom quintile of total testosterone (≤3.3 ng/mL), who might be considered to have clinically low testosterone, were more likely to have elevated CRP (≥3 mg/L) compared with men in the top four quintiles (OR, 1.61; 95% CI, 1.00-2.61). Total and calculated free estradiol (E2) were positively associated with both CRP (Total E2: slope, 0.14; p-trend, <0.001; Free E2: slope, 0.15; p-trend, <0.001) and WBC (Total E2: slope, 0.02; p-trend, 0.08; Free E2: slope, 0.02; p-trend, 0.02) concentrations. SHBG concentrations were inversely associated with WBC count (slope, -0.03; p-trend, 0.04), but not with CRP. These cross-sectional findings are consistent with the hypothesis that higher androgen and lower oestrogen concentrations may have an anti-inflammatory effect in men.

Helicobacter pylori infection assessed by ELISA and by immunoblot and noncardia gastric cancer risk in a prospective study: the Eurgast-EPIC project.

BACKGROUND: In epidemiological studies, Helicobacter pylori infection is usually detected by enzyme-linked immunosorbent assay (ELISA). However, infection can spontaneously clear from the mucosa during the progression of atrophy and could lead to substantial under-detection of infection and underestimation of its effect on gastric cancer (GC) risk. Antibodies detected by western blot are known to persist longer after the loss of the infection. METHODS: In a nested case-control study from the Eurogast-EPIC cohort, including 88 noncardia GC cases and 338 controls, we assessed the association between noncardia GC and H. pylori infection comparing antibodies detected by western blot (HELICOBLOT2.1) to those detected by ELISA (Pyloriset EIA-GIII(®)). RESULTS: By immunoblot, 82 cases (93.2%) were H. pylori positive, 10 of these cases (11.4%) were negative by ELISA and only 6 cases (6.8%) were negative by both ELISA and immunoblot. Multivariable odds ratio (OR) for noncardia GC comparing immunoglobulin G positive versus negative by ELISA was 6.8 [95% confidence interval (CI) 3.0-15.1], and by immunoblot, the OR was 21.4 (95% CI 7.1-64.4). CONCLUSIONS: Using a western blot assay, nearly all noncardia GC were classified as H. pylori positive and the OR was more than threefold higher than the OR assessed by ELISA, supporting the hypothesis that H. pylori infection is a necessary condition for noncardia GC.

Oral contraceptive use and reproductive factors and risk of ovarian cancer in the European Prospective Investigation into Cancer and Nutrition.

BACKGROUND: It is well established that parity and use of oral contraceptives reduce the risk of ovarian cancer, but the associations with other reproductive variables are less clear. METHODS: We examined the associations of oral contraceptive use and reproductive factors with ovarian cancer risk in the European Prospective Investigation into Cancer and Nutrition. Among 327,396 eligible women, 878 developed ovarian cancer over an average of 9 years. Hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated using Cox proportional hazard models stratified by centre and age, and adjusted for smoking status, body mass index, unilateral ovariectomy, simple hysterectomy, menopausal hormone therapy, and mutually adjusted for age at menarche, age at menopause, number of full-term pregnancies and duration of oral contraceptive use. RESULTS: Women who used oral contraceptives for 10 or more years had a significant 45% (HR, 0.55; 95% CI, 0.41-0.75) lower risk compared with users of 1 year or less (P-trend, <0.01). Compared with nulliparous women, parous women had a 29% (HR, 0.71; 95% CI, 0.59-0.87) lower risk, with an 8% reduction in risk for each additional pregnancy. A high age at menopause was associated with a higher risk of ovarian cancer (>52 vs ≤ 45 years: HR, 1.46; 95% CI, 1.06-1.99; P-trend, 0.02). Age at menarche, age at first full-term pregnancy, incomplete pregnancies and breastfeeding were not associated with risk. CONCLUSION: This study shows a strong protective association of oral contraceptives and parity with ovarian cancer risk, a higher risk with a late age at menopause, and no association with other reproductive factors.

Oral contraceptives, reproductive history and risk of colorectal cancer in the European Prospective Investigation into Cancer and Nutrition.

BACKGROUND: Oral contraceptive use and reproductive factors may initiate long-term changes to the hormonal milieu and thereby, possibly influence colorectal cancer risk. METHODS: We examined the association of hormonal and reproductive factors with risk of colorectal cancer among 337,802 women in the European Prospective Investigation into Cancer and Nutrition, of whom 1878 developed colorectal cancer. RESULTS: After stratification for center and age, and adjustment for body mass index, smoking, diabetes mellitus, physical activity and alcohol consumption, ever use of oral contraceptives was marginally inversely associated with colorectal cancer risk (hazard ratio (HR), 0.92; 95% confidence interval (CI), 0.83-1.02), although this association was stronger among post-menopausal women (HR, 0.84; 95% CI: 0.74-0.95). Duration of oral contraceptive use and reproductive factors, including age at menarche, age at menopause, type of menopause, ever having an abortion, parity, age at first full-term pregnancy and breastfeeding, were not associated with colorectal cancer risk. CONCLUSION: Our findings provide limited support for a potential inverse association between oral contraceptives and colorectal cancer risk.