A meta-analysis of genotypes and haplotypes of methylenetetrahydrofolate reductase gene polymorphisms in acute lymphoblastic leukemia

A meta-analysis of case-control studies that investigated the association between the C677T and/or A1298C polymorphisms in the methylenetetrahydrofolate reductase (MTHFR) gene and acute lymphoblastic leukemia (ALL) was carried out. Pooled odds ratios (OR) of various genetic contrasts of each polymorphism were estimated using random (RE) and fixed effects (FE) models. Pooled ORs for combined genotypes and haplotypes were estimated after adjustment for study effect using a log-linear model and the expectation-maximization algorithm in combination with log-linear modeling, respectively. The recessive model for allele 1298C produced a rather marginal association: RE OR: 0.67; 95% confidence interval (CI): 0.46-0.99 and FE OR: 0.64; 95% CI: 0.49-0.84. In Caucasians, the results of the recessive model for allele 1298C was consisted with a protective effect of ALL development: FE OR: 0.63; 95% CI: 0.46-0.87. In childhood ALL, according to the results of the allele contrast and the recessive model for 677T allele it was conceivable that a protective effect exist: RE OR = 0.74; 95% CI: 0.57-0.96 and RE OR: 0.69; 95% CI: 0.51-0.94, respectively. The combined genotypes produced significant pooled OR for the 677CC/1298CC relative to 677CC/1298AA (OR: 0.54; 95% CI: 0.36-0.80). The haplotype 677C/1298C might be more protective to ALL relative to haplotype 677C/1298A (OR: 0.77; 95% CI: 0.61-0.97). When studies not in Hardy-Weinberg equilibrium (HWE) were corrected to account for departures from HWE, then, the pattern of results remained the same. Overall, there is high heterogeneity between the studies in both polymorphisms. A differential magnitude of effect in large versus small studies and alteration of early extremes effects existed.     

孕妇被动吸烟与低出生体重关系的Meta分析

目的分析孕妇孕早期和不同孕期被动吸烟对新生儿低出生体重的影响。方法通过Meta分析方法分析孕妇被动吸烟与新生儿低出生体重之间的关系。对NCBI、OVID-MEDLINE、CNKI、VIP以及CBM数据库进行检索(截止日期为2008年4月),结果报告合并OR值及95%CI。结果共获得26篇文献,其中队列研究20篇,病例对照研究6篇。总体分析,孕妇被动吸烟的合并效应值OR=1.65(95%CI:1.39～1.97);调整合并效应值OR=1.60(95%CI:1.25～2.05);最低和最高暴露量的合并效应值分别为OR=1.53(95%CI:1.14～2.04)和OR=2.53(95%CI:1.46～4.36);孕早期暴露的合并效应值OR=1.12(95%CI:0.82～1.55),没有统计学意义。结论孕妇被动吸烟增加新生儿低出生体重的危险性;孕中晚期可能是被动吸烟效应的敏感期;被动吸烟的阈值是否存在尚不明确。     

Association of maternal short stature with stunting in Mexican children: common genes vs common environment

OBJECTIVE: To evaluate the association between stunting in children and maternal short stature, controlling for potential environmental confounders. DESIGN: 1988 Mexico National Nutrition Survey. Setting: Mexico SUBJECTS: The final sample size was 4663 pairs of children (<5 y) and their mothers (12-49 y) from a total of 13 236 surveyed houses. MAIN OUTCOME MEASURES: Stunting (height-for-age Z-scores <-2). RESULTS: The prevalence of stunting in children was 19%, and 10% of the mothers exhibited short stature (<145 cm). In the crude analysis, mothers with short stature were significantly more likely to have stunted children (odds ratio (OR)=4.0; 95% confidence interval (CI)=3.2-4.8; P-value <0.001). In a multiple logistic regression model the OR for child stunting was reduced, but remained significant OR=2.0; 95% CI=1.6-2.6; P-value <0.001) after adjustment for region, urban/rural residence, socio-economic status, household size, child age and presence of infection in the past 14 d, and maternal age, body mass index (BMI), and educational level. Adjusted ORs varied between regions (Mexico City, OR=3.9; North Mexico, OR=3. 1; Central Mexico, OR=2.0; South Mexico, OR=1.6. Comparison of crude vs adjusted estimates pointed to regional differences in the proportion of association between maternal and child short statures explained by environmental determinants. CONCLUSIONS: Maternal stature, reflecting her potential height and early environment, appeared to contribute to child height independently of the shared risk factors that could affect stature. Nonetheless, we could explain much of the association between stunting in children and maternal short stature by environmental factors, and part of the residual variability may be due to unmeasured determinants. Regional differences pointed to a predominance of environmental factors in explaining child stunting in poorer regions.     

Prospective study of alcohol consumption quantity and frequency and cancer-specific mortality in the US population

Prospective associations between quantity and frequency of alcohol consumption and cancer-specific mortality were studied using a nationally representative sample with pooled data from the 1988, 1990, 1991, and 1997-2004 administrations of the National Health Interview Survey (n = 323,354). By 2006, 8,362 participants had died of cancer. Cox proportional hazards regression was used to estimate relative risks. Among current alcohol drinkers, for all-site cancer mortality, higher-quantity drinking (≥ 3 drinks on drinking days vs. 1 drink on drinking days) was associated with increased risk among men (relative risk (RR) = 1.24, 95% confidence interval (CI): 1.09, 1.41; P for linear trend = 0.001); higher-frequency drinking (≥ 3 days/week vs. <1 day/week) was associated with increased risk among women (RR = 1.32, 95% CI: 1.13, 1.55; P-trend < 0.001). Lung cancer mortality results were similar, but among never smokers, results were null. For colorectal cancer mortality, higher-quantity drinking was associated with increased risk among women (RR = 1.93, 95% CI: 1.17, 3.18; P-trend = 0.03). Higher-frequency drinking was associated with increased risk of prostate cancer (RR = 1.55, 95% CI: 1.01, 2.38; P for quadratic effect = 0.03) and tended to be associated with increased risk of breast cancer (RR = 1.44, 95% CI: 0.96, 2.17; P-trend = 0.06). Epidemiologic studies of alcohol and cancer mortality should consider the independent effects of quantity and frequency.     

Dietary calcium consumption and astrocytic glioma: the San Francisco Bay Area Adult Glioma Study, 1991-1995.

Previous studies suggest an association between calcium consumption and glioma risk. In the present study, we compare consumption of calcium and other dairy components and foods (cholesterol, fat, protein, calories, milk, and cheese) of 337 astrocytic glioma case patients with 450 controls from the San Francisco Bay Area Adult Glioma Study, 1991-1995. We use unconditional logistic regression models to estimate odds ratios (ORs) by gender controlling for age, education, and income. A statistically significant inverse association [p (trend) = 0.05] was observed for dietary calcium intake for women only [OR = 0.49, 95% confidence interval (CI) = 0.24-1.03 for highest vs. lowest quartile of consumption]. In addition, we observed elevated ORs for highest vs. lowest quartiles of cholesterol intake among women and men (OR = 2.07, 95% CI = 1.00-4.28 and OR = 1.75, 95% CI = 0.92-3.31, respectively). Calcium may exert a protective effect through its known roles in apoptosis, DNA repair, and inhibition of parathyroid hormone production. Recent evidence suggests that parathyroid hormone may influence growth and dedifferentiation of astrocytoma cells. Finally, circulating estradiol might directly stimulate intestinal absorption of calcium and may therefore explain why the inverse association of calcium intake and glioma is confined to women.     

中国人群吸烟与喉癌关系的Meta分析

目的综合评价中国人群吸烟与喉癌之间的关系及关联强度,为我国喉癌的防治策略提供依据。方法在CNKI、万方、维普、PubMed、ScienceDirect、SpringerLink、Wiley、ProQuest等数据库中系统检索截止2013年1月之前国内外发表的相关研究文献。所有文献检索、文献选取、文献信息的提取及文献质量评价均由两人独立进行。根据研究之间的异质性大小采用合适的方法来合并相关结果。结果纳入合格研究文献16篇,喉癌患者2730例,对照3224例。吸烟与喉癌发病关系的合并0尺值为4．08（95％CI：2．90—5．26;r=86．7％,P〈0．001）。很少吸烟者及经常吸烟者发生喉癌的OR值为分别为5．90（95％CI：3．05～11．41）及13．30（95％CI：8．03～22．03）。结合漏斗图的结果,尚不能认为目前纳入的研究存在发表偏倚（Egger,P=0．402;Begg,P=0．784）。结论在中国,吸烟会显著增加喉癌的发病风险,而且随着吸烟量的增加,喉癌的风险可能更高。     

Gliomas and farm pesticide exposure in men: the upper midwest health study

The National Institute for Occupational Safety and Health evaluated farm pesticide exposure and glioma risk in a study that included 457 glioma cases and 648 population-based controls, all adult men (18-80 yr old) and nonmetropolitan residents of Iowa, Michigan, Minnesota, and Wisconsin. Multiple logistic regressions were used to control for farm residence, age, age group, education, and exposure to other pesticides. No associations were found between glioma and 12 specific pesticides. We estimated adjusted odds ratios (ORs) and 95% confidence intervals (CIs) and found reduced glioma risk for insecticides (OR = 0.53, CI = 0.37-0.77), fumigants (OR = 0.57, CI = 0.34-0.95), and organochlorines (OR = 0.66, CI = 0.47-0.94). In analyses excluding proxy respondents (47% of cases) most CIs included 1.0. No positive association of farm pesticide exposure and glioma was found. Other farm exposures may explain the excess brain cancer risk seen in previous studies.     

Citrus fruits intake and prostate cancer risk: a quantitative systematic review

OBJECTIVES: The purpose of this systematic review was to investigate the association between dietary intake of citrus fruits and prostate cancer risk. METHODS: Authors searched electronic databases and the reference lists of publications of diet and prostate cancer studies until August 2007. All of the epidemiological studies that obtained individual data on dietary intake of citrus fruits and presented risk estimates of the association between intake of citrus fruits and risk of prostate cancer were identified and included. Using general variance-based methods, study-specific odds ratios (OR)/ relative risk (RR) and associated confidence interval (CI)/ standard error (SE) for highest versus lowest intake of citrus fruits level were extracted from each paper. RESULTS: Eleven articles including six case-control studies, one nested case-control study and four cohort studies, proved eligible. Overall summary OR using random effect model did not show an association in risk of prostate cancer with intake of citrus fruits (summary OR=1.03, 95% CI=0.89-1.19) with large heterogeneity across studies that we were unable to explain (I(2)=67.88%). The summary ORs in case-control studies and cohort studies were 1.10 (95% CI=0.97-1.22) and 1.05 (95% CI=0.96-1.14), respectively. CONCLUSIONS: Pooled results from observational studies did not show an association between intake of citrus fruits and the risk of prostate cancer, although results vary substantially across studies.     

Intergenerational and environmental factors influencing pregnancy outcomes

PURPOSE: Factors that relate to the mother's own course of growth and development might influence later reproductive performances. This study examines the effect of maternal birth weight and maternal height and maternal weight gain, on term-small for gestational age (SGA) and preterm delivery.METHODS: Data used for this study were from the South Carolina Pregnancy Risk Assessment Monitoring System (PRAMS) and birth certificate files for 1993-1995. Since PRAMS data were weighted to adjust for sampling probabilities, non-response and survey design, Survey Data Analysis (SUDAAN) software was used in all analyses.RESULTS: Maternal birth weight was strongly associated with term SGA (OR = 3.65; 95% CI = 1.83-7.29), but not preterm delivery among black mothers; it was associated with preterm delivery (OR = 1.86; 95% CI = 1.09-3.17), but not term-SGA for white mothers. Maternal birth weight was associated with term SGA among nonsmokers only (OR = 2.34; 95% CI = 1.33-4.11). Maternal weight gain modified the effect of height on birth outcomes. Among women with inadequate weight gain, there was a 3-fold increase in risk for term-SGA (OR = 3.06; 95% CI = 2.41-3.89) for short maternal height, but not for preterm delivery. Among women with adequate plus weight gain, the association between short maternal height and term-SGA was 2.7 (95% CI = 0.55-9.43) compared to 3.67 (95% CI = 0.1.41-9.56) between short maternal height and preterm delivery. Maternal weight gain also modified the effect of maternal height on both outcomes for black mothers and for nonsmokers only.CONCLUSIONS: Findings indicate the need for interventions directed to those women who can benefit most from appropriate targeted weight gain recommendations. Therefore, prevention methods should be implemented to encourage short stature women to gain adequate weight during pregnancy.     

Childhood growth and breast cancer

Adult height is known to be positively associated with breast cancer risk. The mechanism underlying this association is complex, since adult height is positively correlated with age at menarche, which in turn is negatively associated with breast cancer risk. The authors used prospective data from a British cohort of 2,547 girls followed from birth in 1946 to the end of 1999 to examine breast cancer risk in relation to childhood growth. As expected, adult height was positively associated with age at menarche and breast cancer. In childhood, cases were taller and leaner, on average, than noncases. Significant predictors of breast cancer risk in models containing all components of growth were height velocity at age 4-7 years (for a one-standard-deviation increase, odds ratio (OR) = 1.54, 95% confidence interval (CI): 1.13, 2.09) and age 11-15 years (OR = 1.29, 95% CI: 0.97, 1.71) and body mass index velocity (weight (kg)/height (m)(2)/year) at age 2-4 years (OR = 0.63, 95% CI: 0.48, 0.83). The effects of these variables were particularly marked in women with early menarche (age <12.5 years). These findings suggest that women who grow faster in childhood and reach an adult height above the average for their menarche category are at particularly increased risk of breast cancer.     

The association of calcium and vitamin D with risk of colorectal adenomas

The Polyp Prevention Trial (PPT) was a multicenter randomized clinical trial designed to determine the effects of a high-fiber, high-fruit and vegetable, low-fat diet on the recurrence of adenomatous polyps in the large bowel. Detailed dietary intake and supplement use data were collected at baseline and at each of 4 annual study visits. Adenoma recurrence was ascertained by complete colonoscopy at baseline and after 1 and 4 y. Recurrence was found in 754 of the 1905 trial participants. We evaluated the association between calcium and vitamin D intake and adenomatous polyp recurrence after adjusting for intervention group, age, gender, nonsteroidal anti-inflammatory drug use, total energy intake, and the interaction of gender and intervention group. Vitamin D models were also adjusted for the location of the clinic site. Dietary variables were adjusted for total energy intake via the residual method. There were no overall significant associations between adenoma recurrence and dietary calcium intake [odds ratio (OR) for the 5th compared with the lowest quintile = 0.91; 95% CI = 0.67-1.23; P-trend = 0.68], total calcium intake (OR = 0.86; 95% CI = 0.62-1.18; P-trend = 0.20), or dietary vitamin D intake (OR = 0.93; 95% CI = 0.69-1.25; P-trend = 0.43) averaged over follow-up. Total vitamin D intake was weakly inversely associated with adenoma recurrence (OR = 0.84; 95% CI = 0.62-1.13; P-trend = 0.03). Supplemental calcium and vitamin D use during follow-up also were inversely associated with adenoma recurrence (OR for any compared with no use = 0.82; 95% CI = 0.68-0.99; and OR = 0.82; 95% CI = 0.68-0.99; for calcium and vitamin D, respectively). Slightly stronger associations were noted for the prevention of multiple recurrences. Our analyses did not suggest a significant effect modification between total calcium and total vitamin D intake (P = 0.14) on risk for adenoma recurrence. This trial cohort provides some evidence that calcium and vitamin D may be inversely associated with adenoma recurrence.     

The association between body height and coronary heart disease among Finnish twins and singletons

OBJECTIVE: An inverse association between body height and the incidence of coronary heart disease (CHD) has been observed. However, the mechanisms behind this association are still largely unknown. We will examine the role of genetic and familial factors behind the association in a large twin data set. DESIGN AND SETTING: The data were derived from the Finnish Twin cohort including 2438 singletons, 4073 monozygotic (MZ) twins, and 9202 dizygotic (DZ) twins aged 25-69 years at baseline in 1976. Incident CHD cases were derived from hospital discharge data and cause of death data between 1977 and 1995. Cox regression analysis and conditional logistic regression analysis were used. RESULTS: In population-level analyses no differences in the general risk of CHD between zygosity groups were found. The association between body height and CHD was similar between sexes and zygosity groups. When men and women in all zygosity groups were studied together an increased risk of CHD was found only among the shortest quartile (hazard ratio [HR] = 1.34, 95% CI: 1.14-1.57). Among the twin pairs discordant for CHD a suggestive increased risk for the shorter twin was seen among DZ twins (odds ratio [OR] = 1.19, 95% CI: 0.95-1.48) when men and women were studied together. CONCLUSION: An inverse association between body height and CHD was broadly similar between sexes and twin zygosity groups and was associated with short stature. Among discordant twin pairs we found a weak association among DZ twins but not MZ twins. This may suggest the role of genetic liability behind the association between body height and CHD.     

Childhood asthma and indoor allergen exposure and sensitization in Buffalo, New York

This nested case-control study examined the association between prevalent asthma and indoor allergen sensitization and/or exposure among children (aged 5-17 years) in Buffalo, New York. The study included a self-administered questionnaire, clinical interviews, skin allergen sensitivity tests and home dust sampling for house dust mites, cat, dog, cockroach and mouse allergens. After adjusting for multiple confounders, asthma cases had higher odds of being sensitized to Der p dust mites (odds ratio [OR]=1.94, 95% confidence interval (CI): 1.13-3.35), cat (OR=1.96, 95% CI: 1.13-3.39), or dog allergens (OR=1.89, 95% CI: 1.10-3.22) than the controls. A significantly positive association between asthma status presence of cat allergen in the child's mattress (ORs: 2.61, 95% CI: 1.09-6.28) was also found. Children with both sensitization and environmental exposure to cat allergens had higher odds of asthma (OR=7.08, 95% CI: 2.12-23.62) than those who were only sensitized to cat allergen (OR=2.31, 95% CI: 1.01-5.32) or had only home exposures (OR=1.47, 95% CI: 0.47-4.65). The association between allergen sensitization and asthma was more consistent than for home exposures. The findings help to confirm the role of allergen sensitization and home exposure in regard to asthma, and suggest that both, individually and jointly, are associated with asthma.     

Meta- and pooled analyses of the methylenetetrahydrofolate reductase C677T and A1298C polymorphisms and gastric cancer risk: a huge-GSEC review

Methylenetetrahydrofolate reductase (MTHFR) is a key enzyme in the metabolism of folate, whose role in gastric carcinogenesis is controversial. The authors performed a meta-analysis and individual data pooled analysis of case-control studies that examined the association between C677T and A1298C polymorphisms (the former being associated with low folate serum levels) and gastric cancer (meta-analyses: 16 studies, 2,727 cases and 4,640 controls for C677T and seven studies, 1,223 cases and 2,015 controls for A1298C; pooled analyses: nine studies, 1,540 cases and 2,577 controls for C677T and five studies, 1,146 cases and 1,549 controls for A1298C). An increased risk was found for MTHFR 677 TT in the meta-analysis (odds ratio (OR) = 1.52, 95% confidence interval (CI): 1.31, 1.77) and pooled analysis (OR = 1.49, 95% CI: 1.14, 1.95). No association resulted for MTHFR 1298 CC (meta-OR = 0.94, 95% CI: 0.65, 1.35; pooled OR = 0.90, 95% CI: 0.69, 1.34). Results from the pooled analysis of four studies on C677T stratified according to folate levels showed an increased risk for individuals with low (OR = 2.05, 95% CI: 1.13, 3.72) versus high (OR = 0.95, 95% CI: 0.54, 1.67) folate levels. Overall, these findings support the hypothesis that folate plays a role in gastric carcinogenesis.     

吸烟、饮酒与食管癌p53基因改变的Meta分析

目的 探讨吸烟、饮酒与食管癌p53基因改变之间的关系。方法 应用Meta分析对有关研究吸烟、饮酒与食管癌p53基因改变的文献进行综合评价。结果 纳入Meta分析的14篇研究吸烟的文献中,吸烟与P53蛋白高表达、p53基因改变(P53蛋白高表达 p53基因突变)的合并OR值分别为1.99(95％CI:1.30～3.06)、1.64(95％CI:1.13～2.37)(P<0.05),吸烟与p53基因突变的合并OR值为1.11(95％CI:0.47～2.76)(P>0.05)。11篇研究饮酒的文献中,饮酒与P53蛋白高表达、p53基因突变和p53基因改变的合并OR值分别为1.30(95％CI:0.83～2.04)、1.13(95％CI:0.67～1.90)和1.22(95％CI:0.87～1.72),合并OR值无统计学意义(P>0.05)。结论 吸烟与p53基因改变有显著联系,饮酒与p53基因改变未见显著联系。     

Agricultural pesticide use and risk of glioma in Nebraska, United States

Background: To evaluate the risk of the adult glioma associated with farming and agricultural pesticide use, the authors conducted a population based case control study in eastern Nebraska. Methods: Telephone interviews were conducted with men and women diagnosed with gliomas (n = 251) between 1988 and 1993 and controls (n = 498) randomly selected from the same geographical area. Unconditional logistic regression was used to calculate adjusted odds ratios (ORs) for farming and for use of individual and chemical classes of insecticides and herbicides, including pesticides classified as nitrosatable (able to form N-nitroso compounds upon reaction with nitrite). Non-farmers were used as the reference category for all analyses. Results: Among men, ever living or working on a farm and duration of farming were associated with significantly increased risks of glioma (?55 years on a farm OR = 3.9, 95% CI 1.8 to 8.6); however, positive findings were limited to proxy respondents. Among women, there were no positive associations with farming activities among self or proxy respondents. Specific pesticide families and individual pesticides were associated with significantly increased risks among male farmers; however, most of the positive associations were limited to proxy respondents. For two herbicides and three insecticides, use was positively associated with risk among both self and proxy respondents. Based on a small number of exposed cases, ORs were significantly increased for the herbicides metribuzin (OR = 3.4, 95% CI 1.2 to 9.7) and paraquat (OR = 11.1, 95% CI 1.2 to 101), and for the insecticides bufencarb (OR = 18.9, 95% CI 1.9 to 187), chlorpyrifos (OR = 22.6, 95% CI 2.7 to 191), and coumaphos (OR = 5.9, 95% CI 1.1 to 32). Conclusion: The authors found significant associations between some specific agricultural pesticide exposures and the risk of glioma among male farmers but not among female farmers in Nebraska; however, most of the positive associations were limited to proxy respondents. These findings warrant further evaluation in prospective cohort studies where issues of recall bias are not a concern.     

Obesity-related eating behaviors are associated with low physical activity and poor diet quality in Spain

This study examined the association of obesity-related eating behaviors (OREB) with physical activity, sedentariness, and diet quality. Data were taken from a cross-sectional study in 10,791 persons representative of the Spanish population who were ≥18 y of age in 2008-2010. The following self-reported information was collected on 12 OREB: not planning how much to eat before sitting down, not deciding the amount of food on the plate, skipping breakfast, eating precooked/canned food or snacks bought at vending machines or at fast-food restaurants, not choosing low-energy foods, not removing visible fat from meat or skin from chicken, eating while watching television or seated on a sofa or an armchair, and taking a short time for meals. Analyses were performed with linear or logistic regression, as appropriate, and adjusted for the main confounders. In comparison to participants with ≤1 OREB, those with ≥5 OREB performed less physical activity [β: -2.61 (95% CI: -4.44, -0.78); P-trend < 0.001] and spent more time watching television [β: 2.17 (95% CI: 1.39, 2.95); P-trend < 0.001]; furthermore, they had greater total energy intake [β: 160 (95% CI: 115, 210); P-trend < 0.001] and were less likely to follow a Mediterranean diet [OR: 0.55 (95% CI: 0.41, 0.73); P-trend < 0.001]. In conclusion, the association between OREB and obesity is biologically plausible because OREB are associated with energy intake and poor accordance with the Mediterranean diet. Studies on the association between OREB and obesity should control for the confounding effect of physical activity and sedentariness.     

A nested case-control study of brain tumors among employees at a petroleum exploration and extraction research facility

Work-related exposures potentially associated with a cluster of brain tumors at a petroleum exploration and extraction research facility were evaluated in a nested case-control study. Fifteen cases were identified in the original cohort and 150 matched controls were selected. Odds ratios (ORs) for occupational exposure to petroleum, radiation, solvents, magnetic fields, and work activities were near or below 1.0. ORs near 1.5 were observed for: working with computers (OR = 1.47; 95% confidence interval [CI] = 0.30-9.35); work-related travel (OR = 1.48; 95% CI = 0.25-5.95), and travel immunizations (OR = 1.62; 95% CI = 0.23-9.45). Higher ORs were observed for work in administrative and marketing buildings and for achieving a master's or higher degree (OR = 2.0, 95% CI = 0.4-10.7). While some ORs above 1.5 were noted, no work-related chemical and physical exposures were significantly associated with the occurrence of brain tumors among employees at this facility.     

Adenocarcinoma of the stomach and esophagus and drinking water and dietary sources of nitrate and nitrite

We conducted a population-based case-control study of adenocarcinoma of the stomach and esophagus in Nebraska, U.S.A. Nitrate concentrations in public drinking water supplies were linked to residential water source histories. Among those using private wells at the time of the interview, we measured nitrate levels in water samples from wells. Dietary nitrate and nitrite were estimated from a food-frequency questionnaire. Among those who primarily used public water supplies (79 distal stomach, 84 esophagus, 321 controls), average nitrate levels were not associated with risk (highest versus lowest quartile: stomach OR=1.2, 95% CI [0.5-2.7]; esophagus OR=1.3, 95% CI [0.6-3.1]). We observed the highest ORs for distal stomach cancer among those with higher water nitrate ingestion and higher intake of processed meat compared with low intakes of both; however, the test for positive interaction was not significant (p=0.213). We did not observe this pattern for esophagus cancer. Increasing intake of nitrate and nitrite from animal sources was associated with elevated ORs for stomach cancer and with a significant positive trend in risk of esophagus cancer (P-trend=0.325 and 0.015, respectively). Larger studies with higher exposures to drinking water sources of nitrate are warranted to further evaluate N-nitroso compound precursors as risk factors for these cancers.     

Meta- and pooled analysis of GSTT1 and lung cancer: a HuGE-GSEC review

Lung cancer is the most common malignancy in the Western world, and the main risk factor is tobacco smoking. Polymorphisms in metabolic genes may modulate the risk associated with environmental factors. The glutathione S-transferase theta 1 gene (GSTT1) is a particularly attractive candidate for lung cancer susceptibility because of its involvement in the metabolism of polycyclic aromatic hydrocarbons found in tobacco smoke and of other chemicals, pesticides, and industrial solvents. The frequency of the GSTT1 null genotype is lower among Caucasians (10-20%) than among Asians (50-60%). The authors present a meta- and a pooled analysis of case-control, genotype-based studies that examined the association between GSTT1 and lung cancer (34 studies, 7,629 cases and 10,087 controls for the meta-analysis; 34 studies, 7,044 cases and 10,000 controls for the pooled analysis). No association was observed between GSTT1 deletion and lung cancer for Caucasians (odds ratio (OR) = 0.99, 95% confidence interval (CI): 0.87, 1.12); for Asians, a positive association was found (OR = 1.28, 95% CI: 1.10, 1.49). In the pooled analysis, the odds ratios were not significant for either Asians (OR = 0.97, 95% CI: 0.83, 1.13) or Caucasians (OR = 1.09, 95% CI: 0.99, 1.21). No significant interaction was observed between GSTT1 and smoking on lung cancer, whereas GSTT1 appeared to modulate occupational-related lung cancer.