BackgroundDiet is a major source of cadmium intake among the non-smoking general population. Recent studies have determined that cadmium exposure may produce adverse health effects at lower exposure levels than previously predicted. We conducted a meta-analysis to combine and analyze the results of previous studies that have investigated the association of dietary cadmium intake and cancer risk.MethodsWe searched PubMed, EMBASE, and MEDLINE database for case-control and cohort studies that assessed the association of dietary cadmium intake and cancer risk. We performed a meta-analysis using eight eligible studies to summarize the data and summary relative risks (RRs) and 95% confidence intervals (CIs) were calculated using a random effects model.ResultsOverall, dietary cadmium intake showed no statistically significant association with cancer risk (RR = 1.10; 95% CI: 0.99–1.22, for highest vs. lowest dietary cadmium group). However, there was strong evidence of heterogeneity, and subgroup analyses were conducted using the study design, geographical location, and cancer type. In subgroup analyses, the positive associations between dietary cadmium intake and cancer risk were observed among studies with Western populations (RR = 1.15; 95% CI: 1.08–1.23) and studies investigating some hormone-related cancers (prostate, breast, and endometrial cancers).ConclusionOur analysis found a positive association between dietary cadmium intake and cancer risk among studies conducted in Western countries, particularly with hormone-related cancers. Additional experimental and epidemiological studies are required to verify our findings.

Soy food is known to contribute greatly to a reduction in the risk of gastric cancer (GC). However, both Japanese and Korean populations have high incidence rates of GC despite the consumption of a wide variety of soy foods. One primary reason is that they consume fermented rather than non-fermented soy foods. In order to assess the varying effects of fermented and non-fermented soy intake on GC risk in these populations, we conducted a meta-analysis of published reports. Twenty studies assessing the effect of the consumption of fermented soy food on GC risk were included, and 17 studies assessing the effect of the consumption of non-fermented soy food on GC risk were included. We found that a high intake of fermented soy foods was significantly associated with an increased risk of GC (odds ratio [OR] = 1.22, 95% confidence interval [CI] = 1.02-1.44, I 2 = 71.48), whereas an increased intake of non-fermented soy foods was significantly associated with a decreased risk of GC (overall summary OR = 0.64, 95% CI = 0.54-0.77, I 2 = 64.27). These findings show that a high level of consumption of non-fermented soy foods, rather than fermented soy foods, is important in reducing GC risk. (Cancer Sci 2011; 102: 231-244) G astric cancer (GC) is the most common cancer in Japan and Korea and the second leading cause of death from cancer globally, although the incidence and mortality have been declining over the years.(1) Dietary factors are known to play an important role in the development of GC.(2) Among dietary factors, soy has been of considerable interest in the etiology of GC.(3) It is widely known that soy foods may help reduce the risk of developing GC. This might be due to the fact that soy foods are good sources of isoflavones, which are antioxidants known to reduce the risk of GC.(3) However, despite the fact that Japanese and Korean populations generally have a high intake of soy foods, they also have a higher risk of GC than other populations, including those in the USA and Europe.This might be explained by the fact that Japanese and Korean populations consume more fermented soy foods than nonfermented ones. Common fermented soy foods, which generally contain a high content of salt, include soy paste and fermented soybeans.(3) The most common non-fermented soy foods include soymilk, tofu, soybeans and soy nuts. There is a contradictory relationship between the intake of soy food and GC; GC risk increases with the intake of fermented soy foods and decreases with the intake of non-fermented soy foods. (4) Fermented soy may offer health benefits due to the fermentation process. However, it may have adverse effects on GC risk due to high levels of nitrate or nitrite, large amounts of salt, and the loss of key nutrients under acidic and oxygenic conditions.An extensive meta-analysis of the relationships between fermented soy foods and GC risk has not been conducted. Thus, we carried out a meta-analysis of the relationships between the consumption of fermented and non-fermented soy foods and GC risk in Japanese an...

Background The liability to addiction has been shown to be highly genetically correlated across drug classes, suggesting nondrug-specific mechanisms. Methods In 757 subjects, we performed association analysis between 1536 single nucleotide polymorphisms (SNPs) in 106 candidate genes and a drug use disorder diagnosis (DUD). Results Associations (p ≤ .0008) were detected with three SNPs in the arginine vasopressin 1A receptor gene, AVPR1A, with a gene-wise p value of 3 × 10−5. Bioinformatic evidence points to a role for rs11174811 (microRNA binding site disruption) in AVPR1A function. Based on literature implicating AVPR1A in social bonding, we tested spousal satisfaction as a mediator of the association of rs11174811 with the DUD. Spousal satisfaction was significantly associated with DUD in males (p <.0001). The functional AVPR1A SNP, rs11174811, was associated with spousal satisfaction in males (p = .007). Spousal satisfaction was a significant mediator of the relationship between rs11174811 and DUD. We also present replication of the association in males between rs11174811 and substance use in one clinically ascertained (n = 1399) and one epidemiologic sample (n = 2231). The direction of the association is consistent across the clinically-ascertained samples but reversed in the epidemiologic sample. Lastly, we found a significant impact of rs11174811 genotype on AVPR1A expression in a postmortem brain sample. Conclusions The findings of this study call for expansion of research into the role of the arginine vasopressin and other neuropeptide system variation in DUD liability.

Generally, larger sample size leads to a greater statistical power to detect a significant difference. We may increase the sample size for both case and control in order to obtain greater power. However, it is often the case that increasing sample size for case is not feasible for a variety of reasons. In order to look at change in power as the ratio of control to case varies (1:1 to 4:1), we conduct association tests with simulated data generated by PLINK. The simulated data consist of 50 disease SNPs and 300 non-disease SNPs and we compute powers for disease SNPs. Genetic Power Calculator was used for computing powers with varying the ratio of control to case (1:1, 2:1, 3:1, 4:1). In this study, we show that gains in statistical power resulting from increasing the ratio of control to case are substantial for the simulated data. Similar results might be expected for real data.

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