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Abstract Background The x-ray cross complementing group 1 gene (XRCC1) is crucial to proper repair of DNA damage such as single-strand DNA breaks. A non-synonymous polymorphism in XRCC1, 399 G → A, has been shown to reduce effectiveness of such DNA repair and has been associated with the risk of certain cancers. The known risk for glioma from high dose ionizing radiation makes associations between this polymorphism and glioma of particular interest. Methods A systematic literature review and meta-analysis was conducted to explore the association between XRCC1 399 G → A and glioma. Subgroup analyses by grade, gender, genotyping method, country in which study was conducted, and study size were conducted when data were available and validity of the results were assessed by influence analyses and exploration of potential publication bias. Results Six studies were eligible for meta-analysis including data on 2,362 Caucasian glioma cases and 3,085 Caucasian controls. Pooled analysis yielded a significant association between the variant of interest and risk of glioma (OR = 1.17, 95% CI: 1.05-1.30) which was found to be disproportionately driven by a single study. Exclusion of this study, in an influence analysis, produced no statistically significant evidence of association with glioma (OR = 1.10, 95% CI: 0.98-1.23), and no evidence of publication bias. Conclusions This meta-analysis does not suggest a major role of the XRCC1 399 G → A polymorphism in influencing risk of glioma among Caucasians. Future studies should report data separately for glioma subtypes to permit stratified analyses for Grade III and Grade IV glioma and examine other polymorphisms in this gene.

Background: Overweight and obesity are associated with breast cancer mortality. However, the relationship between postdiagnosis weight gain and mortality is unclear. We conducted a systematic review and meta-analysis of weight gain after breast cancer diagnosis and breast cancer-specific, all-cause mortality and recurrence outcomes.Methods: Electronic databases identified articles up through December 2014, including: PubMed (1966-present), EMBASE (1974-present), CINAHL (1982-present), and Web of Science. Language and publication status were unrestricted. Cohort studies and clinical trials measuring weight change after diagnosis and all-cause/breast cancer-specific mortality or recurrence were considered. Participants were women age 18 years or older with stage I-IIIC breast cancer. Fixed effects analysis summarized the association between weight gain (≥5.0% body weight) and all-cause mortality; all tests were two-sided.Results: Twelve studies (n = 23 832) were included. Weight gain (≥5.0%) compared with maintenance (<±5.0%) was associated with increased all-cause mortality (hazard ratio [HR] = 1.12, 95% confidence interval [CI] = 1.03 to 1.22, P = .01, I(2) = 55.0%). Higher risk of mortality was apparent for weight gain ≥10.0% (HR = 1.23, 95% CI = 1.09 to 1.39, P < .001); 5% to 10.0% weight gain was not associated with all-cause mortality (P = .40). The association was not statistically significant for those with a prediagnosis body mass index (BMI) of less than 25 kg/m(2) (HR = 1.14, 95% CI = 0.99 to 1.31, P = .07) or with a BMI of 25 kg/m(2) or higher (HR = 1.00, 95% CI = 0.86 to 1.16, P = .19). Weight gain of 10.0% or more was not associated with hazard of breast cancer-specific mortality (HR = 1.17, 95% CI = 1.00 to 1.38, P = .05).Conclusions: Weight gain after diagnosis of breast cancer is associated with higher all-cause mortality rates compared with maintaining body weight. Adverse effects are greater for weight gains of 10.0% or higher. [ABSTRACT FROM AUTHOR]

Background: Childhood asthma and obesity prevalence have increased in recent years suggesting a potential association. However, the direction of any association is poorly understood and the potential causal-relationship is unknown. Methods: We examined the association between overweight/obesity, defined by body mass index (BMI) <18 years of age, and subsequent physician-diagnosed incident asthma at least one year after BMI assessment. We sought to explore potential effect modification by sex. PubMed and Embase were searched using keywords and restricted to subjects aged 0-18 years. There were no date or language restrictions. From each study we extracted: authors, publication date, location, overweight/obesity definitions, asthma definitions, number of participants, recruitment duration, description of cohort, follow-up time, adjusted effect estimates (with 95% CI) and estimates of subgroup analysis. Results: Six prospective cohort studies which focused on children <18 years of age met criteria for inclusion. The combined risk ratio (RR) of overweight was associated with asthma (RR = 1.35; 95% CI = 1.15, 1.58). In boys, the combined RR of overweight on asthma was significant (RR = 1.41; 95% CI = 1.05, 1.88). For girls, when BMI was defined by Z-score, the combined RR of overweight on asthma was also significant (RR = 1.19; 95% CI = 1.06, 1.34). The combined risk ratio (RR) of obesity was associated with asthma in both boys and girls (RR = 1.50; 95% CI = 1.22, 1.83), in boys only (RR = 1.40; 95% CI = 1.01, 1.93) and in girls only (RR = 1.53; 95% CI = 1.09, 2.14). Conclusions: Overweight and, especially, obese children are at increased risk of subsequent physician diagnosed asthma in comparison to normal weight children. Except for sex, no studies reported any other potential effect modifiers. The observed sex effects were inconsistent. [ABSTRACT FROM AUTHOR]

Objective: Systematic review and meta-analysis to investigate the association between maternal AGTR1 gene single nucleotide polymorphisms (SNPs) and preeclampsia (PE). Methods: A systematic literature search was performed using PubMed, EMBASE, Scopus, and HuGE Literature Finder databases. The review was conducted according to PRISMA guidelines. Summary odds ratios (ORs) for the allelic and genotypic contrasts were calculated and compared to indicate the most appropriate genetic model for the polymorphism of interest. Among-study heterogeneity was assessed using the I2 statistic and publication bias was evaluated visually using funnel plots. Results: Seven maternal SNPs investigated with PE were found, but only AGTR1 +1166A>C accumulated sufficient evidence for meta-analysis. Summary ORs calculated from eight studies (10 populations involving 845 PE cases and 1150 controls) did not reveal an association between the +1166A>C polymorphism and PE (allelic OR = 1.19, 95% CI: 0.96-1.47). No evidence of publication bias and among-study heterogeneity was detected. Conclusions: meta-analysis findings did not support AGTR1 +1166A>C as a susceptibility locus for PE. Other AGTR1 SNPs require more study. [ABSTRACT FROM AUTHOR]

Background Small birth size may be associated with increased risk of cardiovascular diseases (CVD), whereas large birth size may predict increased risk of obesity and some cancers. The net effect of birth size on long-term mortality has only been assessed in individual studies, with conflicting results.Methods The Meta-analyses of Observational Studies in Epidemiology (MOOSE) guidelines for conducting and reporting meta-analysis of observational studies were followed. We retrieved 22 studies that assessed the association between birthweight and adult mortality from all causes, CVD or cancer. The studies were systematically reviewed and those reporting hazard ratios (HRs) and 95% confidence intervals (95% CIs) per kilogram (kg) increase in birthweight were included in generic inverse variance meta-analyses.Results For all-cause mortality, 36 834 deaths were included and the results showed a 6% lower risk (adjusted HR = 0.94, 95% CI: 0.92–0.97) per kg higher birthweight for men and women combined. For cardiovascular mortality, the corresponding inverse association was stronger (HR = 0.88, 95% CI: 0.85–0.91). For cancer mortality, HR per kg higher birthweight was 1.13 (95% CI: 1.07–1.19) for men and 1.04 (95% CI: 0.98–1.10) for women (Pinteraction = 0.03). Residual confounding could not be eliminated, but is unlikely to account for the main findings.Conclusion These results show an inverse but moderate association of birthweight with adult mortality from all-causes and a stronger inverse association with cardiovascular mortality. For men, higher birthweight was strongly associated with increased risk of cancer deaths. The findings suggest that birthweight can be a useful indicator of processes that influence long-term health. [ABSTRACT FROM AUTHOR]

In the clinical management of early-stage cutaneous melanoma, it is critical to determine which patients are cured by surgery alone and which should be treated with adjuvant therapy. To assist in this decision, many groups have made an effort to use molecular information. However, although there are hundreds of studies that have sought to assess the potential prognostic value of molecular markers in predicting the course of cutaneous melanoma, at this time, no molecular method to improve risk stratification is part of recommended clinical practice. To help understand this disconnect, we conducted a systematic review and meta-analysis of the published literature that reported immunohistochemistry-based protein biomarkers of melanoma out- come. Three parallel search strategies were applied to the PubMed database through January 15, 2008, to identify cohort stud- ies that reported associations between immunohistochemical expression and survival outcomes in melanoma that conformed to the REMARK criteria. Of the 102 cohort studies, we identified only 37 manuscripts, collectively describing 87 assays on 62 distinct proteins, which met all inclusion criteria. Promising markers that emerged included melanoma cell adhesion molecule (MCAM)/MUC18 (all-cause mortality [ACM] hazard ratio [HR] = 16.34; 95% confidence interval [Cl] = 3.80 to 70.28), matrix met- alloproteinase-2 (melanoma-specific mortality [MSM] HR = 2.6; 95% Cl = 1.32 to 5.07), Ki-67 (combined ACM HR = 2.66; 95% Cl = 1.41 to 5.01), proliferating cell nuclear antigen (ACM HR = 2.27; 95% Cl = 1.56 to 3.31), and p16/INK4A (ACM HR = 0.29; 95% Cl = 0.10 to 0.83, MSM HR = 0.4; 95% Cl = 0.24 to 0.67). We further noted incomplete adherence to the REMARK guidelines: 14 of 27 cohort studies that failed to adequately report their methods and nine studies that failed to either perform multivariable analyses or report their risk estimates were published since 2005. [ABSTRACT FROM AUTHOR]

Modern microarray genotyping now permits simultaneous analysis of tens of thousands of polymorphisms, and this technology is being widely used to associate the role of genes with the etiology of complex disease. Genome-wide hypothesis-free mapping will also increasingly generate candidate genes that require further testing in association studies. At the same time, genetic effects are increasingly observed to be buffered by a wide array of biologic mechanisms that evolved to protect the genome from environmental insult and that serve to obscure observation of direct effects of polymorphisms on a disease phenotype. These two forces combine to make replication of genomic epidemiology extraordinarily difficult. Traditional research synthesis of emerging bodies of genomic epidemiology is problematic and often quickly outdated. The author proposes that electronic evidence-based methodology, perhaps modeled after that used by the Cochrane Collaboration in clinical medicine, would facilitate the systematic preparation and frequent updating of systematic reviews, which is essential for identifying valid and replicable gene-disease associations. [ABSTRACT FROM AUTHOR]

Background: Tanning beds are associated with increased risk of melanoma. Objective: We sought to update the evidence of the association of melanoma and indoor tanning focusing on frequency of use and exposure to newer tanning beds. Methods: We searched Scopus, MEDLINE, and Cumulative Index to Nursing and Allied Health Literature on August 14, 2013. We included all observational studies that included patients with melanoma who had indoor tanned. Odds ratios (OR) with 95% confidence intervals (CI) were extracted and combined using generic inverse variance methods assuming a random effects model. Results: In all, 31 studies were included with data available on 14,956 melanoma cases and 233,106 controls. Compared with never using, the OR for melanoma associated with ever using indoor tanning beds was 1.16 (95% CI 1.05-1.28). Similar findings were identified in recent studies with enrollment occurring in the year 2000 onward (OR 1.22, 95% CI 1.03-1.45) and in subjects attending more than 10 tanning sessions (OR 1.34, 95% CI 1.05-1.71). Limitations: The quality of evidence contributing to review results ranges from poor to mediocre. Conclusion: Using tanning beds is associated with a subsequent melanoma diagnosis. Exposure from more than 10 tanning sessions is most strongly associated and there was no statistically significant difference in this association before and after 2000, suggesting that newer tanning technology is not safer than older models. [Copyright &y& Elsevier]

Therapy for childhood acute lymphoblastic leukemia (ALL) is associated with 5-year survival rates of ∼90% even after largely eliminating cranial radiation. This meta-analysis assesses the long-term neurocognitive functioning after chemotherapy-only regimens among survivors of childhood ALL. We conducted a systematic review to identify studies that evaluated long-term neurocognitive functioning following treatment of ALL by searching MEDLINE/PubMed, Database of Abstracts of Reviews of Effects, and secondary sources. Studies were included if ALL survivors were in continuous first remission, did not receive any radiation, were at least ≥2 years off therapy or ≥5 years since diagnosis, and were compared with a healthy control group. Weighted mean differences with 95% confidence intervals (CIs) were calculated. Ten nonexperimental studies met all eligibility criteria and included 509 patients and 555 controls. Meta-analysis demonstrated statistically significant moderate impairment across multiple neurocognitive domains evaluated, with intelligence most affected. Significant differences in standard deviation (SD) scores were found for Full Scale intelligence quotient (IQ) (-0.52 SD; 95% CI, -0.68 to -0.37), Verbal IQ (-0.54 SD; 95% CI, -0.69 to -0.40), and Performance IQ (-0.41 SD; 95% CI, -0.56 to -0.27); these SD scores correspond to changes in IQ of 6 to 8 points. Working memory, information processing speed, and fine motor domains were moderately, but statistically significantly, impaired. Meta-analysis of ALL survivors treated without cranial radiation demonstrated significant impairment in IQ and other neurocognitive domains. Patients and their families should be informed about these potential negative effects to encourage surveillance and educational planning. Both preventive and intervention strategies are needed. [ABSTRACT FROM AUTHOR]

CONTEXT: The increasing prevalence of childhood asthma has been associated with low microbial exposure as described by the hygiene hypothesis. OBJECTIVE: We sought to evaluate the evidence of association between antibiotic exposure during pregnancy or in the first year of life and risk of childhood asthma. METHODS: PubMed was systematically searched for studies published between 1950 and July 1, 2010. Those that assessed associations between antibiotic exposure during pregnancy or in the first year of life and asthma at ages 0 to 18 years (for pregnancy exposures) or ages 3 to 18 years (for first-year-of-life exposures) were included. Validity was assessed according to study design, age at asthma diagnosis, adjustment for respiratory infections, and consultation rates. RESULTS: For exposure in the first year of life, the pooled odds ratio (OR) for all studies (N = 20) was 1.52 (95% confidence interval [CI]: 1.30-1.77). Retrospective studies had the highest pooled risk estimate for asthma (OR: 2.04 [95% CI: 1.83-2.27]; n = 8) compared with database and prospective studies (OR: 1.25 [95% CI: 1.08-1.45]; n = 12). Risk estimates for studies that adjusted for respiratory infections (pooled OR: 1.16 [95% CI: 1.08-1.25]; n = 5) or later asthma onset (pooled OR for asthma at or after 2 years: OR: 1.16 [95% CI: 1.06-1.25]; n = 3) were weaker but remained significant. For exposure during pregnancy (n = 3 studies), the pooled OR was 1.24 (95% CI: 1.02-1.50). CONCLUSIONS: Antibiotics seem to slightly increase the risk of childhood asthma. Reverse causality and protopathic bias seem to be possible confounders for this relationship. [ABSTRACT FROM AUTHOR]

Objectives: We estimated the prevalence of renal impairment in heart failure (HF) patients and the magnitude of associated mortality risk using a systematic review of published studies. Background: Renal impairment in HF patients is associated with excess mortality, although precise risk estimates are unclear. Methods: A systematic search of MEDLINE (through May 2005) identified 16 studies characterizing the association between renal impairment and mortality in 80,098 hospitalized and non-hospitalized HF patients. All-cause mortality risks associated with any renal impairment (creatinine >1.0 mg/dl, creatinine clearance [CrCl] or estimated glomerular filtration rate [eGFR] <90 ml/min, or cystatin-C >1.03 mg/dl) and moderate to severe impairment (creatinine ≥1.5, CrCl or eGFR <53, or cystatin-C ≥1.56) were estimated using fixed-effects meta-analysis. Results: A total of 63% of patients had any renal impairment, and 29% had moderate to severe impairment. After follow-up ≥1 year, 38% of patients with any renal impairment and 51% with moderate to severe impairment died versus 24% without impairment. Adjusted all-cause mortality was increased for patients with any impairment (hazard ratio [HR] = 1.56; 95% confidence interval [CI] 1.53 to 1.60, p < 0.001) and moderate to severe impairment (HR = 2.31; 95% CI 2.18 to 2.44, p < 0.001). Mortality worsened incrementally across the range of renal function, with 15% (95% CI 14% to 17%) increased risk for every 0.5 mg/dl increase in creatinine and 7% (95% CI 4% to 10%) increased risk for every 10 ml/min decrease in eGFR. Conclusions: Renal impairment is common among HF patients and confers excess mortality. Renal function should be considered in risk stratification and evaluation of therapeutic strategies for HF patients. [Copyright &y& Elsevier]