Exposure to multiple trace elements and thyroid cancer risk in Chinese adults: A case-control study.

The incidence of thyroid cancer (TC) has increased rapidly in last decades. Multiple trace elements in the external environment have important effects with thyroid function. However, the evidence for these on TC risk were rarely reported. A total of 585 newly diagnosed TC patients and 585 healthy controls were included in this study, and 14 urinary elements were measured to explain the fixed-exposure effect on TC risk. Conditional logistic regressions were used to reflect the multi-element associations, and Bayesian kernel machine regression (BKMR) was applied to show the tendency of mixed effects. Furthermore, the interaction effects were examined by Generalized linear model (GLM). The levels of lithium (Li), cobalt (Co), strontium (Sr), zinc (Zn) and copper (Cu) had negative effects with TC risk, nevertheless lead (Pb), arsenic (As) and chromide (Cr) showed positive effects. The BKMR and GLM models reflected the effect fluctuations of different elements, and there was a slight interaction effects between Li and Cr, Co, Zn and Pb. Further study is required to confirm these results in the future.

Reproductive and menstrual factors for papillary thyroid cancer risk: A case-control study in Chinese women.

BACKGROUND: Thyroid cancer (TC) is threefold more common in women than men. Reproductive and menstrual factors may be related to the onset of papillary thyroid cancer (PTC). This study aims to determine the association of reproductive and menstrual factors with PTC in Chinese females. METHODS: A total of 335 histologically confirmed cases of PTC were recruited in this case-control study. The controls were matched for age with a deviation of ± 2 years, which conducted from September 2016 to February 2019. Logistic regression models were applied to identify the association of reproductive and menstrual factors with PTC. RESULTS: After adjustment by some variables, early menarche age (OR ≤ 13 years vs. > 13years = 2.40, 95 % CI 1.12-5.13) and shorter lifetime breastfeeding (OR <6 months vs. ≥ 6 months = 1.99, 95 % CI 1.11-3.55) significantly increased the risk of PTC, whereas younger age at first pregnancy had a protective effect against PTC (OR ≤ 24years vs. > 24 years = 0.66, 95 % CI 0.44-0.98). There was a positive correlation between premenopausal and PTC in the lower age group (OR premenopausal vs. Menopause by natural =2.34, 95 %CI 1.03-5.28). CONCLUSIONS: Early menarche age, abortion, shorter breastfeeding duration and premenopausal may be related to the occurrence of PTC. Early age at first pregnancy and larger number of full-time pregnancies were possible to decrease the risk of PTC.

Exposure to 2,4-dichlorophenol, 2,4,6-trichlorophenol, pentachlorophenol and risk of thyroid cancer: a case-control study in China.

Thyroid cancer (TC) has inflicted huge threats to the health of mankind. Chlorophenols (CPs) were persistent organic pollutant and can lead to adverse effects in human health, especially in thyroid. However, epidemiological studies have revealed a rare and inconsistent relationship between internal exposure to CPs and TC risk. The purpose of this study was to investigate the correlation between urinary CPs and TC risk in Chinese population. From June 2017 to September 2019, a total of 297 histologically confirmed TC cases were recruited. Age- and gender-matched controls were enrolled at the same time. Gas chromatography-mass spectrometry (GC-MS) was used to determine the levels of three CPs in urine. Conditional logistic regression models were adopted to assess the potential association. Restricted cubic spline function was used to explore the non-liner association. After adjusting for confounding factors, multivariate analysis showed that, compared with the first quartile, the fourth quartile concentrations of 2,4-dichlorophenol (2,4-DCP), 2,4,6-trichlorophenol (2,4,6-TCP), and pentachlorophenol (PCP) were associated with TC risk (odds ratio (OR)2,4-DCP =2.28, 95% confidence interval (CI): 1.24-4.18; OR2,4,6-TCP =3.09, 95% CI: 1.66-5.77; ORPCP =3.30, 95% CI: 1.71-6.36, respectively), when CPs were included in the multivariate model and restricted cubic spline function as continuous variables, presenting significant dose-response relationships. Meanwhile, whether in the TC group with tumor diameter > 1 cm or metastatic TC, the changes of 2,4,6 TCP and PCP concentrations were positively correlated with the risk of TC. Our study suggests that higher concentrations of urinary CPs are associated with increased TC risks. Moreover, 2,4,6-TCP and PCP have certain effects on the invasiveness of thyroid cancer. Targeted public health policies should be formulated to reduce the CP pollution. These findings need further in-depth studies to confirm and relevant mechanism also needed to be clarified.

Association of exposure to multiple metals with papillary thyroid cancer risk in China.

Papillary thyroid cancer (PTC) has inflicted huge threats to the health of mankind. Metal pollution could be a potential risk factor of PTC occurrence, but existing relevant epidemiological researches are limited. The current case-control study was designed to evaluate the relationships between exposure to multiple metals and the risk of PTC. A total of 262 histologically confirmed PTC cases were recruited. Age- and gender-matched controls were enrolled at the same time. Urine samples were used as biomarkers to reflect the levels of environmental exposure to 13 metals. Conditional logistic regression models were adopted to assess the potential association. Single-metal and multi-metal models were separately conducted to evaluate the impacts of single and co-exposure to 13 metals. The increased concentration of urinary Cd, Cu, Fe, and Pb quartiles was found significant correlated with PTC risk. We also found the decreased trends of urinary Se, Zn, and Mn quartiles with the ORs for PTC. These dose-response associations between Pb and PTC were observed in the single-metal model and remained significant in the multi-metal model (OR25-50th=1.39, OR50-75th=3.32, OR>75th=7.62, p for trend <0.001). Our study suggested that PTC was positively associated with urinary levels of Cd, Cu, Fe, Pb, and inversely associated with Se, Zn, and Mn. Targeted public health policies should be made to improve the environment and the recognition of potential risk factors. These findings need additional studies to confirm in other population.