Hypomethylation of repetitive elements in blood leukocyte DNA and risk of gastric lesions in a Chinese population

BackgroundTo explore the association between hypomethylation of repetitive elements (LINE-1, Sat2, and ALU) in blood leukocyte DNA and risks of gastric lesions, and development of gastric cancer (GC), a population-based study was conducted in a high-risk area of GC in China.MaterialsMethylation levels were determined by MethyLight in 902 subjects with various gastric lesions from two cohort studies at baseline and 276 subjects with long-term follow-up data.ResultsThe frequency of LINE-1 or Sat2 hypomethylation was significantly increased in subjects with dysplasia (DYS) compared with superficial gastritis/chronic atrophic gastritis. The odds ratios (ORs) were 2.22 [95% confidence interval (CI): 1.45–3.40] for LINE-1 and 1.58 (95% CI: 1.14–2.21) for Sat2. A dose–response pattern was found for the risk of DYS and LINE-1 hypomethylation (P-trend < 0.001). Further stratified analysis indicated that the frequency of LINE-1 or Sat2 hypomethylation was higher in subjects with Helicobacter pylori infection. The ORs were 1.83 (95% CI: 1.12–2.99) for LINE-1 and 1.44 (95% CI: 1.01–2.05) for Sat2. The follow-up data indicated that the risk of progression to GC was increased in intestinal metaplasia (IM) subjects with LINE-1 hypomethylation (OR = 2.82; 95% CI: 1.17–6.77) or Sat2 hypomethylation (OR = 2.78; 95% CI: 1.15–6.74). The risk of progression to GC was also increased in DYS subjects with Sat2 hypomethylation (OR = 5.24; 95% CI: 2.00–13.74).ConclusionsThese findings suggest that hypomethylation of repetitive elements in blood leukocytes is associated with the risks of advanced gastric lesions and development of GC.     

Association between hypermethylation of DNA repetitive elements in white blood cell DNA and early-onset colorectal cancer

Changes in the methylation levels of DNA from white blood cells (WBCs) are putatively associated with an elevated risk for several cancers. The aim of this study was to investigate the association between colorectal cancer (CRC) and the methylation status of three DNA repetitive elements in DNA from peripheral blood. WBC DNA from 539 CRC cases diagnosed before 60 years of age and 242 sex and age frequency-matched healthy controls from the Australasian Colorectal Cancer Family Registry were assessed for methylation across DNA repetitive elements Alu, LINE-1 and Sat2 using MethyLight. The percentage of methylated reference (PMR) of cases and controls was calculated for each marker. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated using multivariable logistic regression adjusted for potential confounders. CRC cases demonstrated a significantly higher median PMR for LINE-1 (p < 0.001), Sat2 (p < 0.001) and Alu repeats (p = 0.02) when compared with controls. For each of the DNA repetitive elements, individuals with PMR values in the highest quartile were significantly more likely to have CRC compared with those in the lowest quartile (LINE-1 OR = 2.34, 95%CI = 1.48–3.70; p < 0.001, Alu OR = 1.83, 95%CI = 1.17–2.86; p = 0.01, Sat2 OR = 1.72, 95%CI = 1.10–2.71; p = 0.02). When comparing the OR for the PMR of each marker across subgroups of CRC, only the Alu marker showed a significant difference in the 5-fluoruracil treated and nodal involvement subgroups (both p = 0.002). This association between increasing methylation levels of three DNA repetitive elements in WBC DNA and early-onset CRC is novel and may represent a potential epigenetic biomarker for early CRC detection.     

Association of physical activity and polymorphisms in FGFR2 and DNA methylation related genes with breast cancer risk

PurposePhysical activity, a protective factor for breast cancer, increases the level of DNA methylation. Fibroblast growth factor receptor 2 (FGFR2), a confirmed breast cancer susceptibility gene, is predisposed to be methylated. Therefore, DNA methylation related genes, such as methylenetetrahydrofolate reductase (MTHFR), methionine synthase (MTR), and DNA methyltransferase (DNMT), together with physical activity and FGFR2, may interact with each other to effect breast cancer risk.MethodsA total of 839 incident breast cancer cases and 863 age-matched controls from Guangzhou, China were included in this study. We used questionnaires to assess physical activity in metabolic equivalent (MET)-h/week/year and a matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry platform to ascertain genotypes. Odds ratios (OR) and 95% confidence intervals (CI) were calculated from logistic regression models.ResultsExercise activity and FGFR2 rs2981582 were confirmed to be associated with breast cancer risk, and were found to significantly interact (P for multiplicative and additive interactions = 0.045 and 0.021, respectively). Women who had CT/TT genotypes of FGFR2 rs2981582 and experienced exercise activity <3 MET-h/week/year had significantly increased risk (OR = 3.15, 95% CI = 2.28–4.35) compared to women with CC genotype and ≥3 MET-h/week/year. There was also a significant interaction between FGFR2 rs2981582 and MTHFR rs1801133 on breast cancer risk (P for multiplicative and additive interactions = 0.039 and 0.023, respectively).ConclusionWe found both a gene–environment (FGFR2-exercise activity) and a gene–gene (FGFR2–MTHFR) interaction on breast cancer risk. Our results suggest that environmental factors, such as physical activity, may be able to counteract genetic susceptibility to breast cancer.     

Sex steroid-induced DNA methylation changes and inflammation response in prostate cancer

BackgroundSex steroid hormones have been reported to induce inflammation causing dysregulation of cytokines in prostate cancer cells. However, the underlying epigenetic mechanism has not well been studied. The objective of this study was to evaluate the effect of sex steroid hormones on epigenetic DNA methylation changes in prostate cancer cells using a signature PCR methylation array panel that correspond to 96 genes with biological function in the human inflammatory and autoimmune signals in prostate cancer. Of the 96-gene panel, 32 genes showed at least 10% differentially methylation level in response to hormonal treatment when compared to untreated cells. Genes that were hypomethylated included CXCL12, CXCL5, CCL25, IL1F8, IL13RAI, STAT5A, CXCR4 and TLR5; and genes that were hypermethylated included ELA2, TOLLIP, LAG3, CD276 and MALT1. Quantitative RT-PCR analysis of select genes represented in a cytokine expression array panel showed inverse association between DNA methylation and gene expression for TOLLIP, CXCL5, CCL18 and IL5 genes and treatment of prostate cancer cells with 5′-aza-2′-deoxycytidine with or without trichostatin A induced up-regulation of TOLLIP expression. Further analysis of relative gene expression of matched prostate cancer tissues when compared to benign tissues from individual patients with prostate cancer showed increased and significant expression for CCL18 (2.6-fold; p < 0.001), a modest yet significant increase in IL5 expression (1.17-fold; p = 0.015), and a modest increase in CXCL5 expression (1.4-fold; p = 0.25). In conclusion, our studies demonstrate that sex steroid hormones can induce aberrant gene expression via differential methylation changes in prostate carcinogenesis.     

Smoking and other risk factors for pancreatic cancer: A cohort study in men in Lithuania

Background: Cancer of the pancreas is a relatively rare, but highly fatal cancer worldwide. Cigarette smoking has been recognized as an important risk factor, but the relation to other potential determinants is still inconsistent. We investigated the association between different lifestyle, biological and anthropometric factors and the risk of pancreatic cancer in a prospective population-based cohort study from Kaunas, Lithuania. Methods: Our study included 7132 urban men initially free from any diagnosed cancer, followed for up to 30 years. 77 incident cases of pancreatic cancer were identified. Cox proportional hazards regression models were used to estimate hazard ratios (HR) and corresponding 95% confidence intervals (95% CI). Results: Compared to never smokers, current smokers had a significantly increased risk of pancreatic cancer, HR was 1.79 (95% CI 1.03–3.09) after adjustment for age, body mass index, education and alcohol consumption. Among smokers, a significant association with higher smoking intensity was shown (≥20 cigarettes/day: HR = 2.60; 95% CI 1.42–4.76, P_trend = 0.046). We also observed a significantly increased risk for ≥30 pack-years of smoking (HR = 2.24; 95% CI 1.12–4.49, P_trend = 0.16) and for age at starting smoking <18 years (HR = 2.29; 95% CI 1.11–4.70, P_trend = 0.43) as compared to never smokers. Alcohol consumption, body mass index and total cholesterol level were not significantly associated with pancreatic cancer. Conclusions: Smoking significantly increases pancreatic cancer incidence and its high prevalence in Lithuania may partly explain high incidence of the disease. No convincing evidence was found that alcohol consumption, body mass index or serum cholesterol level were associated with pancreatic cancer risk, although the assessment was limited by the lack of statistical power.     

BRCA1 promoter methylation in peripheral blood DNA was identified in sporadic breast cancer and controls

Objective Epigenetics, particularly DNA methylation, has recently been shown to be important in breast cancer initiation. We investigated the clinical and prognostic importance of whole blood breast cancer early onset gene 1 (BRCA1) DNA methylation in sporadic breast cancer. Methods Genomic DNA was extracted from the peripheral blood cells (PBCs) of 902 breast cancer patients at diagnosis, with no BRCA1 mutation, and 990 control women. DNA methylation was measured by quantitative analysis of methylated alleles (QAMA) to estimate the extent of methylation of 2 CpG sites in the promoter region of BRCA1 oncosuppressor. Results BRCA1 promoter methylation rate in PBCs was 47.1% with a 95% confidence interval [46.1; 48.1] in breast cancer patients, and 45.9% with a 95% confidence interval [45.0; 46.8] in controls. We found a trend toward BRCA1 promoter hypermethylation in PBCs of sporadic breast cancer patients compared with controls. Association between methylation and clinicopathological features was evaluated using statistical tests. BRCA1 promoter methylation in PBCs increased significantly in breast cancer patients compared with controls, for age over 70 years (p = 0.022), in post-menopausal status (p = 0.013), for a body mass index (BMI) <20 (p = 0.0095) or a waist-to-hip ratio (WHR) ≤76.8 (p = 0.0027). We also found an association of increased BRCA1 promoter methylation in PBCs with ACA/ACA genotype for the SNP Thr594Thr in ESR (estrogen receptor gene), known to be associated with breast cancer risk (p = 0.092), reflecting the reduced presence of this genotype in this breast cancer case-control study. Conclusion Analysis of site-specific DNA methylation in PBCs by QAMA provides quantitative DNA methylation values that may serve as important prognostic indicators.     

CHEK2 gene alterations in the forkhead-associated domain, 1100delC and del5395 do not modify the risk of sporadic pancreatic cancer

Checkpoint kinase 2 gene (CHEK2) alterations increase risk of several cancer types. We analyzed selected CHEK2 alterations in 270 Czech pancreatic cancer patients and in 683 healthy controls. The pancreatic cancer risk was higher in individuals who inherited rare alterations in CHEK2 region involving forkhead-associated domain other than I157T (OR = 5.14; 95% CI = 0.94–28.23) but the observed association was non-significant (p = 0.057). The most frequent I157T mutation did not alter the pancreatic cancer risk and neither the followed deletion of 5395 bp nor c.1100delC were found in any of pancreatic cases. We conclude that the I157T, other alterations in its proximity, del5395 and c.1100delC in CHEK2 do not predispose to pancreatic cancer risk in the Czech population.     

No association between educational level and pancreatic cancer incidence in the European Prospective Investigation into Cancer and Nutrition

Introduction: Until now, studies examining the relationship between socioeconomic status and pancreatic cancer incidence have been inconclusive. Aim: To prospectively investigate to what extent pancreatic cancer incidence varies according to educational level within the European Prospective Investigation into Cancer and Nutrition (EPIC) study. Methods: In the EPIC study, socioeconomic status at baseline was measured using the highest level of education attained. Hazard ratios by educational level and a summary index, the relative indices of inequality (RII), were estimated using Cox regression models stratified by age, gender, and center and adjusted for known risk factors. In addition, we conducted separate analyses by age, gender and geographical region. Results: Within the source population of 407, 944 individuals at baseline, 490 first incident primary pancreatic adenocarcinoma cases were identified in 9 European countries. The crude difference in risk of pancreatic cancer according to level of education was small and not statistically significant (RII = 1.14, 95% CI 0.80–1.62). Adjustment for known risk factors reduced the inequality estimates to only a small extent. In addition, no statistically significant associations were observed for age groups (adjusted RII_{≤ 60 years} = 0.85, 95% CI 0.44–1.64, adjusted RII_{>60 years} = 1.18, 95% CI 0.73–1.90), gender (adjusted RII_male = 1.20, 95% CI 0.68–2.10, adjusted RII_female = 0.96, 95% CI 0.56–1.62) or geographical region (adjusted RII_{Northern Europe} = 1.14, 95% CI 0.81–1.61, adjusted RII_{Middle Europe} = 1.72, 95% CI 0.93–3.19, adjusted RII_{Southern Europe} = 0.75, 95% CI 0.32–1.80). Conclusion: Despite large educational inequalities in many risk factors within the EPIC study, we found no evidence for an association between educational level and the risk of developing pancreatic cancer in this European cohort.     

Effects of polymorphisms in translesion DNA synthesis genes on lung cancer risk and prognosis in Chinese men

PurposeTranslesion DNA synthesis (TLS) plays an important role in promoting replication through DNA lesions. Genetic polymorphisms in TLS genes may have potential roles in lung cancer development in humans.MethodsWe evaluated the association between genetic variants in six TLS genes and the risk and survival of lung cancer in a case–control study in China. Included in the study are 224 lung cancer patients and 448 healthy controls.ResultsCarriers of the G allele of POLκ rs5744724 had significantly reduced risk of lung cancer (odds ratio (OR) = 0.62, 95% confidence interval (CI): 0.44–0.89), comparing with those carrying the C allele, and the AA genotype of PCNA rs25406 was also associated with significantly decreased cancer risk compared with the major homozygote alleles (OR = 0.47, 95% CI: 0.25–0.86). Haplotype analysis showed that subjects with the POLκ C-G (rs5744533–rs5744724) haplotype had decreased risk of lung cancer (OR = 0.69, 95% CI: 0.49–0.98), comparing with those carrying the C-C haplotype. Besides, the heterozygote of REV1 rs3087386 and rs3792136 were independent prognostic factors for lung cancer survival with hazard radio (HR) 1.54 (95% CI: 1.12–2.12) and 1.44 (95% CI: 1.06–1.97) respectively.ConclusionsOur findings suggested that genetic variants in POLκ and PCNA genes may play roles in the susceptibility of lung cancer, and REV1 gene may have roles in lung cancer survival in Chinese men.     

Consumption of fruits,vegetables, and seaweeds (sea vegetables) and pancreatic cancer risk: The Ohsaki Cohort Study

Studies on the effects of consumption of fruits, vegetables, and seaweeds on the incidence of pancreatic cancer are not conclusive. We examined the association (if any) between the consumption of fruits, vegetables, and seaweeds and the risk of pancreatic cancer in Japan. Data from 32,859 participants registered in the Ohsaki National Health Insurance Cohort Study who were 40–79 years old and free of cancer at baseline were analyzed. Consumption of fruits, vegetables, and seaweeds was assessed at baseline using a self-administered food frequency questionnaire (containing 40 items). Incidences of pancreatic cancer were identified by computer linkage with the Miyagi Prefectural Cancer Registry. During 11 years of follow-up, 137 pancreatic cancers (67 men and 70 women) were identified. The hazard ratios (95% confidence interval) of pancreatic cancer risk for the highest versus the lowest tertile were 0.82 (0.40–1.68, trend P = 0.57) in men and 0.64 (0.35–1.20, trend P = 0.22) in women for total consumption of fruits, 0.89 (0.46–1.73, trend P = 0.76) in men and 0.67 (0.33–1.35, trend P = 0.23) in women for total consumption of vegetables, and 0.92 (0.46–1.84, trend P = 0.81) in men for consumption of seaweeds (results for the consumption of seaweeds in women were not analyzed because of poor reliability), respectively. Total consumption of fruits, vegetables, and seaweeds was not associated with a reduced risk of pancreatic cancer.     

Both genetic and dietary factors underlie individual differences in DNA damage levels and DNA repair capacity

The interplay between dietary habits and individual genetic make-up is assumed to influence risk of cancer, via modulation of DNA integrity. Our aim was to characterize internal and external factors that underlie inter-individual variability in DNA damage and repair and to identify dietary habits beneficial for maintaining DNA integrity.Habitual diet was estimated in 340 healthy individuals using a food frequency questionnaire and biomarkers of antioxidant status were quantified in fasting blood samples. Markers of DNA integrity were represented by DNA strand breaks, oxidized purines, oxidized pyrimidines and a sum of all three as total DNA damage. DNA repair was characterized by genetic variants and functional activities of base and nucleotide excision repair pathways.Sex, fruit-based food consumption and XPG genotype were factors significantly associated with the level of DNA damage. DNA damage was higher in women (p = 0.035). Fruit consumption was negatively associated with the number of all measured DNA lesions, and this effect was mediated mostly by β-cryptoxanthin and β-tocopherol (p < 0.05). XPG 1104His homozygotes appeared more vulnerable to DNA damage accumulation (p = 0.001). Sex and individual antioxidants were also associated with DNA repair capacity; both the base and nucleotide excision repairs were lower in women and the latter increased with higher plasma levels of ascorbic acid and α-carotene (p < 0.05).We have determined genetic and dietary factors that modulate DNA integrity. We propose that the positive health effect of fruit intake is partially mediated via DNA damage suppression and a simultaneous increase in DNA repair capacity.     

Genetic factors in individual radiation sensitivity

Cancer risk and radiation sensitivity are often associated with alterations in DNA repair, cell cycle, or apoptotic pathways. Interindividual variability in mutagen or radiation sensitivity and in cancer susceptibility may also be traced back to polymorphisms of genes affecting e.g. DNA repair capacity. We studied possible associations between 70 polymorphisms of 12 DNA repair genes with basal and initial DNA damage and with repair thereof. We investigated DNA damage induced by ionizing radiation in lymphocytes isolated from 177 young lung cancer patients and 169 cancer-free controls. We also sought replication of our findings in an independent sample of 175 families (in total 798 individuals). DNA damage was assessed by the Olive tail moment (OTM) of the comet assay. DNA repair capacity (DRC) was determined for 10, 30 and, 60 min of repair.Genes involved in the single-strand-repair pathway (SSR; like XRCC1 and MSH2) as well as genes involved in the double-strand-repair pathway (DSR; like RAD50, XRCC4, MRE11 and ATM) were found to be associated with DNA damage. The most significant association was observed for marker rs3213334 (p = 0.005) of XRCC1 with basal DNA damage (B), in both cases and controls. A clear additive effect on the logarithm of OTM was identified for the marker rs1001581 of the same LD-block (p = 0.039): B_CC = −1.06 (95%-CI: −1.16 to −0.96), B_CT = −1.02 (95%-CI: −1.11 to −0.93) and B_TT = −0.85 (95%-CI: −1.01 to −0.68). In both cases and controls, we observed significantly higher DNA basal damage (p = 0.007) for carriers of the genotype AA of marker rs2237060 of RAD50 (involved in DSR). However, this could not be replicated in the sample of families (p = 0.781). An alteration to DRC after 30 min of repair with respect to cases was observed as borderline significant for marker rs611646 of ATM (involved in DSR; p = 0.055), but was the most significant finding in the sample of families (p = 0.009).Our data indicate that gene variation impacts measurably on DNA damage and repair, suggesting at least a partial contribution to radiation sensitivity and lung cancer susceptibility.     

Differences in DNA methylation by extent of breast cancer family history in unaffected women

Breast cancer clusters within families but genetic factors identified to date explain only a portion of this clustering. Lower global DNA methylation in white blood cells (WBC) has been associated with increased breast cancer risk. We examined whether WBC DNA methylation varies by extent of breast cancer family history in unaffected women from high-risk breast cancer families. We evaluated DNA methylation levels in LINE-1, Alu and Sat2 in 333 cancer-free female family members of the New York site of the Breast Cancer Family Registry, the minority of which were known BRCA1 or BRCA2 mutation carriers. We used generalized estimated equation models to test for differences in DNA methylation levels by extent of their breast cancer family history after adjusting for age. All unaffected women had at least one sister affected with breast cancer. LINE-1 and Sat2 DNA methylation levels were lower in individuals with 3 or more (3+) first-degree relatives with breast cancer relative to women with only one first-degree relative. For LINE-1, Alu, and Sat2, having 3+ affected first-degree relatives was associated with a decrease of 23.4% (95%CI = −46.8%, 0.1%), 17.9% (95%CI = −39.5%, 3.7%) and 11.4% (95% CI = −20.3%, −2.5%), respectively, relative to individuals with only one affected first-degree relative, but the results were only statistically significant for Sat2. Individuals having an affected mother had 17.9% lower LINE-1 DNA methylation levels (95% CI = −28.8%, −7.1%) when compared with those not having an affected mother. No associations were observed for Alu or Sat2 by maternal breast cancer status. If replicated, these results indicate that lower global WBC DNA methylation levels in families with extensive cancer histories may be one explanation for the clustering of cancers in these families. Family clustering of disease may reflect epigenetic as well as genetic and shared environmental factors.     

Analysis of O6-methylguanine-DNA methyltransferase methylation status in sporadic colon polyps

Background/aimThe aim of our study was to check how MGMT methylation status together with known factors influenced the risk of colon cancer development.Materials and methodsWe examined patients with colon polyps. Information concerning gender, age, lifestyle, diet, anthropometry and medical information, including cancer and family history of cancer, was analyzed. Polymorphism variety of MGMT gene was investigated in another study. Genetic analysis for MGMT methylation assessment was performed for polyp tissue samples from 143 patients.ResultsPositive methylation MGMT status was found in 55 patients. There was no correlation between gender and MGMT methylation status (p = 0.43). We did not find correlation between patients younger and older than 60 (p = 0.87). There was no correlation between smoking and MGMT methylation status (p = 0.36). We did not find correlation between BMI and MGMT methylation status (p = 0.86). We did not find correlation between MGMT methylation status and colon cancer in familial history (p = 0.45).ConclusionOur study showed no correlations between methylation status of MGMT polymorphisms and clinical features like age, gender, polyp localization, smoking status, or obesity. It has been shown previously that MGMT methylation status may show nonspecific methylation in colon polyps. Gene methylation status in adenoma tissues has also been associated by other authors with the adenoma's size, histology, and degree of atypia. In our study, we evaluated the gene methylation status in colon polyps and found no association with adenoma characteristics. The present study showed no correlation for MGMT methylation in polyps in different regions of colon.     

Association between TNF-α-308 G/A gene polymorphism and gastric cancer risk: A systematic review and meta-analysis

ObjectiveTumor necrosis factor-alpha (TNF-α) has been found to be associated with gastric carcinogenesis, but individually published results have been inconclusive. The aim of this study was to explore the relationship between the TNF-α-308 G/A polymorphism and gastric cancer risk.MethodsMEDLINE, EMBASE and the COCHRANE library databases were searched for relevant articles to identify all available data. The odds ratios (ORs) with 95% confidence intervals (95% CIs) from each study were used to assess the association between the TNF-α-308 G/A polymorphism and gastric cancer risk.ResultsThis meta-analysis included 30 studies (32 datasets) involving 7009 gastric cancer cases and 12,119 control subjects. Overall, a significant association was found between the TNF-α-308 G/A polymorphism and gastric cancer in AA + GA vs. GG (dominant contrast model) (OR = 1.20, 95% CI = 1.07–1.34, p = 0.001). With stratification based on ethnicity, the TNF-α-308 G/A polymorphism was correlated with gastric cancer risk in Caucasians, using the dominant contrast model (OR = 0.74, 95% CI = 0.57–0.96, p = 0.02), but not in East Asians and other ethnic groups. In the comprehensive subgroup analysis, a significant association was also found in recent articles (published after 2005), population-based high-quality studies, hospital-based high-quality studies, studies using the TaqMan method and non-cardia subgroups. However, the TNF-α-308 G/A polymorphism was not associated with specific histological types of gastric cancer risk.ConclusionsThe TNF-α-308 G/A polymorphism may contribute to susceptibility to gastric cancer in Caucasians, especially for non-cardia gastric cancer, as most strongly demonstrated in high-quality studies and in studies using the TaqMan genotyping method. Furthermore, we recommend the TaqMan method as the preferred genotyping method in DNA polymorphism studies.     

Polymorphisms of the DNA repair gene MGMT and risk and progression of head and neck cancer

Methylating agents are involved in carcinogenesis, and the DNA repair protein O⁶-methylguanine-DNA methyltransferase (MGMT) removes methyl group from O⁶-methylguanine. Genetic variation in DNA repair genes has been shown to contribute to susceptibility to squamous cell carcinoma of the head and neck (SCCHN). We hypothesize that MGMT polymorphisms are associated with risk of SCCHN. In a hospital-based case–control study of 721 patients with SCCHN and 1234 cancer-free controls frequency-matched by age, sex and ethnicity, we genotyped four MGMT polymorphisms, two in exon 3, 16195C > T and 16286C > T and two in the promoter region, 45996G > T and 46346C > A. We found that none of these polymorphisms alone had a significant effect on risk of SCCHN. However, when these four polymorphisms were evaluated together by the number of putative risk genotypes (i.e. 16195CC, 16286CC, 45996GT + TT, and 46346CA + AA), a statistically significantly increased risk of SCCHN was associated with the combined genotypes with three to four risk genotypes, compared with those with zero to two risk genotypes (adjusted odds ratio (OR) = 1.27; 95% confidence interval (CI) = 1.05–1.53). This increased risk was also more pronounced among young subjects (OR = 1.81; 95% CI = 1.11–2.96), men (OR = 1.24; 95% CI = 1.00–1.55), ever smokers (OR = 1.25; 95% = 1.01–1.56), ever drinkers (OR = 1.29; 95% CI = 1.04–1.60), patients with oropharyngeal cancer (OR = 1.45; 95% CI = 1.12–1.87), and oropharyngeal cancer with regional lymph node metastasis (OR = 1.52; 95% CI = 1.16–1.89). In conclusion, our results suggest that any one of MGMT variants may not have a substantial effect on SCCHN risk, but a joint effect of several MGMT variants may contribute to risk and progression of SCCHN, particularly for oropharyngeal cancer, in non-Hispanic whites.     

Serum pepsinogen level,atrophic gastritis and the risk of incident pancreatic cancer—A prospective cohort study

Background: Pancreatic cancer is a highly fatal disease without screening tests. Studies have suggested possible etiologic similarities between gastric and pancreatic cancers. Atrophic gastritis, a pre-malignant condition for gastric cancer, is characterized by low serum pepsinogen I (SPGI) level. We hypothesized that low SPGI level may be associated with an increased risk of pancreatic cancer and be a useful biomarker for the disease. Methods: Our analytic cohort included 20,962 participants in the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study (ATBC) who had SPGI level measured. Of these, 1663 (7.9%) subjects had low SPGI levels (<25 μg/l) and were invited for gastroscopy which was completed in 1059 (63.7%) participants. Atrophic gastritis was histologically confirmed in 1006 (95.0%) subjects. We used Cox proportional hazards regression to calculate the hazard ratios (HR) and 95% confidence intervals (CI) for pancreatic cancer. Results: During follow-up of up to 16.3 years (mean = 10.8 years; 226,325 person-years), 227 incident pancreatic cancers were diagnosed. The incidence rates were 9.9, 11.3, and 12.7 per 10,000 person-years of follow-up for participants with normal pepsinogen level (≥25 μg/l), low pepsinogen level and histologically confirmed atrophic gastritis, respectively. Compared to subjects with normal pepsinogen levels, there was no statistically significant increased risk of pancreatic cancer among subjects with low pepsinogen level (adjusted HR = 1.01; 95% CI: 0.63–1.62) or those with histologically confirmed atrophic gastritis (adjusted HR = 1.13; 95% CI: 0.66–1.95). Conclusions: Atrophic gastritis, serological or histological, is not associated with increased risk of pancreatic cancer. These findings do not provide any evidence for potential usefulness of SPGI for pancreatic cancer screening.     

Association between ultraviolet radiation,skin sun sensitivity and risk of pancreatic cancer

Background: Ecological studies showing an inverse association between pancreatic cancer incidence and mortality and levels of ultraviolet radiation (UVR), suggest that higher levels of sun exposure may reduce risks of pancreatic cancer but there has been only one individual-level study that examined this issue. We aimed to examine the association between pancreatic cancer and markers of exposure to solar UVR, namely skin type, treatment of skin lesions, ambient UVR and time outdoors on work days. Methods: We used data from an Australian case-control study. Location at birth, residential location during adulthood, outdoors work, history of skin lesion treatment and sensitivity of the skin to the sun were obtained by questionnaire. We limited the analyses to Caucasians who answered the questionnaire about UVR (controls = 589/711 recruited; cases = 496/705 recruited). We used NASA's Total Ozone Mapping Spectrometer to estimate ambient UVR. Results: Being born in or living in areas of higher ambient UVR (compared to lower ambient UVR) was associated with about 30–40% lower risk of pancreatic cancer. People with fair skin colour had 47% lower risk of pancreatic cancer than those with dark skin colour (95% CI 0.37–0.75). There was some suggestion of increased risk with increased average number of hours spent outside at work. Conclusions: This study suggests that people with light skin colour or those born or living in areas of high ambient UVR have lower risk of pancreatic cancer. Our analysis supports an association between UVR and pancreatic cancer, possibly mediated through production of vitamin D.     

Genetic polymorphism of epidermal growth factor 61A>G and cancer risk: A meta-analysis

Background: Numerous studies have investigated the risk of cancer associated with the polymorphism of epidermal growth factor (EGF) 61A>G, but the results have been inconsistent. We performed this meta-analysis to drive a more precise estimation of association between this polymorphism and risk of cancer. Methods: Electronic searches of PubMed and EMBASE were conducted to select studies. Case-control studies containing available genotype frequencies of EGF 61A>G were chose, and Odds ratio (OR) with 95% confidence interval (CI) was used to assess the strength of this association. Results: 23 case-control studies including 5578 cases and 7306 controls were identified. This meta-analysis showed significant effect of EGF 61A>G on cancer risk (GG vs. AA: OR = 1.34, 95%CI = 1.05–1.72; GG vs. GA + AA: OR = 1.23, 95%CI = 1.03–1.47; GG + GA vs. AA: OR = 1.18, 95%CI = 1.02–1.38). In subgroup analysis, significant increased risk was found in gastric cancer and glioma in additive model (OR = 1.54, 95%CI = 1.13–2.12; OR = 1.69, 95%CI = 1.21–2.37) and in recessive model (OR = 1.29, 95%CI = 1.10–1.52; OR = 1.54, 95%CI = 1.16–2.04). Conclusion: This meta-analysis suggested that the EGF 61G allele is a risk factor of cancer, especially for gastric cancer and glioma.