Toenail mineral concentration and risk of esophageal squamous cell carcinoma, results from the Golestan Cohort Study

Abstract

Studies conducted in China linked selenium deficiency to higher risk of esophageal squamous cell carcinoma (ESCC), but this has not been widely tested outside that selenium‐deficient region. The aim of this study was to investigate the association between selenium and other mineral concentrations in toenails and risk of ESCC in a region with high incidence rates. In this nested case–control study, we identified 222 cases of ESCC from the Golestan Cohort Study, Iran, which has followed up 50,045 participants since enrollment (2004–2008). We randomly selected one control for each case matched by age and sex, using incidence density sampling. We used toenail samples collected at baseline to measure the concentration of selenium, zinc, chromium, mercury, and scandium using instrumental neutron activation analysis. Multivariate adjusted logistic regression models were used to estimate odds ratios (OR) and 95% confidence intervals. Median nail selenium, zinc, chromium, and mercury levels were 1.01, 74.59, 0.77, and 0.018 μg/g in cases and 1.02, 75.71, 0.71, and 0.023 μg/g in controls, respectively. The adjusted odds ratios comparing each fourth quartile of mineral status versus the first quartile were as follows: selenium = 0.78 (95% CI, 0.41–1.49); zinc=0.80 (95% CI, 0.42–1.53); chromium = 0.91 (95% CI, 0.46–1.80); and mercury=0.61 (95% CI, 0.27–1.38), and all trend tests were non–significant. The nail selenium concentration in our controls reflects relatively high selenium status. No evidence of association between selenium or chromium concentrations in toenails and the risk of ESCC was detected in this population.

Methylmercury exposure, genetic variation in metabolic enzymes, and the risk of glioma

“…With respect to generalizability, it is important to consider how mercury exposures in the present study compare with those in prior studies and with average population exposures. Toenail Hg concentrations were substantially lower in the present study population when compared to those reported in several other US-based 18,40–42 studies, and studies outside the US 35,43–47 , several of which involved toenail measurements performed in the same laboratory as in the present study 35,42,45 . The primary source of MeHg exposure in humans is the dietary consumption of fish, with highest concentrations found in longer-lived, larger fish that bioaccumulate MeHg 8,9,48 .…”

“…To the best of our knowledge, this is the first population study to examine MeHg as a risk factor for glioma and is unique in cancer studies by examining both a biomarker of exposure (toenail Hg) and polymorphic variation in MeHg metabolism 35 . Crespo-Lopez et al .…”

Diet, nutrition, and cancer risk: what do we know and what is the way forward?

“…People in high risk populations have often consumed a restricted diet, low in fruit, vegetables, and animal products, so deficiencies of micronutrients have been postulated to explain the high risk (boxes 1 and 2). Despite several observational studies and some randomised trials, however, the relative roles of various micronutrients are not yet clear 17181920. In Western countries early case-control studies indicated a protective role for fruit and vegetables,2122 but more recently published prospective studies show weaker associations, which might be due to residual confounding from smoking and alcohol consumption 16…”

Association of Selenium and Risk of Esophageal Cancer: A Review

“…Cohort studies in the Netherlands revealed an inverse association between selenium level in the toenail and risk of ESSC (107). However, a case-control study in the Golestan Province did not find such correlation (108). In a Chinese population, low dietary selenium intake was found as a major risk factor for ESSC (109), especially in smokers and heavy drinkers with p53 Pro/Pro and GSTP1 Ile/Ile genotypes (110).…”