Environmental exposure to cadmium and risk of thyroid cancer from national industrial complex areas: A population-based cohort study

摘要

Background: Cadmium is known to act as a thyroid disruptor and carcinogen in humans. Recent evidence suggests that cadmium may play a role as a thyroid carcinogen due to its endocrine-disrupting activity, but this characterization remains unclear.Objective: We investigated the association between urinary cadmium and primary thyroid cancer, and the modifying effect of diabetes on this association.Methods: We included 5406 participants over 19 years old with measured urinary cadmium from samples collected at eight National Industrial Complex areas from 2003 to 2011. Among 5406 participants, 68 cases were diagnosed with thyroid cancer between enrollment and the end of follow-up (December 31, 2016). Incidence rate ratios for thyroid cancer were estimated using random-effects Cox proportional hazards models with follow-up time as the time scale. In addition, we conducted a stratified analysis by diabetes status.Results: Compared with the lowest tertile, the middle and highest tertiles had higher risks of thyroid cancer, respectively (HRmiddle (vs. lowest) =1.90, 95% CI = 0.93 to 3.91; HRhighest vs. lowest = 2.28, 95% CI =1.09 to 4.78), with a significant dose-response relationship (P for trend = 0.03). There was no linear association between cadmium level and risk of thyroid cancer. Higher cadmium levels increased thyroid cancer risk in participants without diabetes (HRmiddle vs. lowest = 2.35, 95% CI = 1.05 to 5.24; HRhighest vs. lowest = 2.70, 95% CI = 1.18 to 6.19); although, an association between cadmium levels and thyroid cancer risk in participants with diabetes was not found.Conclusion: Low-level exposure to cadmium is associated with thyroid cancer risk. Our results provide the evidence to limit exposure to cadmium for cancer prevention in the general population. Further studies are needed to investigate the consequence of diabetes and antidiabetic drugs between cadmium and thyroid cancer. (C) 2020 Elsevier Ltd. All rights reserved.