The Relationship Between Dietary Iodine Intake And Thyroid Cancer Risk: Systematic Review

Objective: The goal of the study was to confirm the relationships of iodine intake and thyroid cancer risk by summarizing the current articles about it in English and Chinese and to provide reliable evidence of evidence-based medicine for the prevention and control of the disease.Methods: Medline, Embase, CNKI(China National Knowledge Infrastructure),Wanfang and CBM(China Biology Medicine disc) were used to identify potential studies and reference lists were scanned for further studies.Two researchers checked the titles,abstracts,and full texts to obtain eligible case-control and cohort studies independently.The methodological quality was evaluated.Data were extracted and classified. Review Manager 5.2 and Comprehensive Meta-Analysis V2 were used.Results: We collected 20 studies on the relationships of iodine intake and thyroid cancer risk,included 3 studies with specific amount data of dietary iodine intake,6 studies on saltwater fish,5 studies on shellfish and 14 studies on fish.Conclusions: More than adequate or excess iodine intake(>300μg/day) or high consumption of saltwater fish(≥3times/week) decreased thyroid cancer risk(OR=0.74, 95%CI=0.60-0.92, I2=0%, p=0.007; OR=0.69, 95%CI=0.53-0.90, I2=15%, p=0.006). Thyroid cancer risk was also decreased in Caucasian with high(≥3times/week) consumption of fish(OR=0.75, 95%CI=0.63-0.90, I2=0%,p=0.02).The study didn’t show significant relationship between shellfish and thyroid carcinoma risk.