The impact of obesity and insulin resistance on thyroid cancer: A systematic review

In recent decades, there has been a marked increase in the prevalence of thyroid cancer. This phenomenon has paralleled the increase in the prevalence of obesity worldwide, which is associated with insulin resistance. Associations between these entities have been hypothesized, mainly for older and female populations, but they remain unclear. The aim of this article is to systematically review the literature in an attempt to determine whether the increase in the prevalence of thyroid cancer is due to obesity or due only to improved detection with the better imaging techniques available. A thorough literature search on PubMed and application of selection criteria identified 15 appropriate studies. The detailed analysis of the data from these studies indicated that there is a suggestive association between thyroid cancer, obesity, insulin resistance and hyperinsulinemia for both genders. Therefore, the increased prevalence of thyroid cancer is not dependent on improved detection only. Further research should be performed for complete understanding of the pathophysiological associations, especially regarding adipose tissue and genetics, but also for the improvement of preventive public health policies.