Sadeghi H, et al. – Objective of this study was to calculate the amount of excess risk that attributed to risk factors. It was illustrated that a significant amount of the incidence of thyroid cancer is attributable to lifestyle risk factors. Since these factors are entirely preventable, so it is necessary to reduce factors that are correlated with increased thyroid cancer risk and proper education to the community. Therefore weight loss and protection against radiation can effectively reduce the incidence rate of thyroid cancer but smoking can have a protective effect.

Methods

• Researchers searched major electronic databases until February 2016.
• They included epidemiological studies addressing the association between lifestyle risk factors and thyroid cancer.
• The outcomes were expressed as ARF with 95% confidence intervals (CIs) using a random–effects–model.

Results

• They distinguished a sum of 13 321 references and included 17 studies.
• The data indicated that excess risk of thyroid cancer attributable to radiation exposure was 14% (95% CI: 5%, 23%; eight studies, I2 = 88.7%), to obesity was 13% (95% CI: 5%, 21%; four studies, I2 = 68.7%), to overweight was 10% (95% CI: 2%, 17%; four studies, I2 = 4.1%) and to smoking was -13% (95% CI: -33%, 6%; five studies, I2 = 30.6%).
• It was noted that obesity, overweight and radiation exposure are significantly correlated with increased thyroid cancer risk and smoking has a protective effect on thyroid cancer but not significant.