Rotating shift work Is Associated with increased risk of thyroid carcinoma ： an ecological study of 178905 workers in 35 European countries between 2000 and 2015

Objective: Previous studies have shown that circadian disruption can affect thyroid hormone levels, but whether it elevates the risk of thyroid cancer (TC) is still controversial. The present study investigates the relationship between rotating shift work (RSW) and the incidence of TC. Methods: : The prevalence of RSW in the 35 European countries from 2000 to 2015 was estimated based on the data of 89257 men and 81749 women of the European Working Condition Survey. The incidence of TC was obtained from the Global Burden of Disease database. We analyzed the relationship between the prevalence of RSW and the incidence of TC 5 years later (TC5). We used a mixed model with adjustment of country-specific GDP per capita, Volcanic region, age, Education attainment rate, obesity rate and occupational radiation exposure rate. Results: : The prevalence of RSW was significantly associated with the incidence of TC5 (β = 0.03 95%CI:0.01, 0.06, P=0.03). For a quartile increase in RSW, the incidence of TC5 increased by 0.18 per 100000（95%CI：0.05 per 100000,0.33 per 100000）. When separately analyzed in the two genders, we found an association between the two in women (β = 0.04, 95%CI: 0.01, 0.08, P=0.02), but not in men (β = 0.01, 95% CI: -0.03, 0.04, P=0.75). Conclusion: Circadian disruption may be associated with an increase in the overall risk of TC, but it only seems to affect the occurrence of TC in women, not men. Further research is needed to verify the findings of the present study.