Obesity and thyroid cancer: epidemiologic associations and underlying mechanisms

Abstract

The incidence of thyroid cancer has been rising over the past few decades along with a parallel increase in obesity. Observational studies have provided evidence for a potential association between the two. By contrast, clinical data for a link between type 2 diabetes mellitus, a condition strongly associated with obesity, and thyroid cancer are limited and largely not supportive of such an association. Obesity leads to hypoadiponectinemia, a pro-inflammatory state, and insulin resistance, which, in turn, leads to high circulating insulin and insulin-like growth factor-1 levels, thereby possibly increasing the risk for thyroid cancer. Thus, insulin resistance possibly plays a pivotal role in underlying the observed association between obesity and thyroid cancer, potentially leading to the development and/or progression of thyroid cancer, through its interconnections with other factors including insulin-like growth factor-1, adipocytokines/cytokines and thyroid-stimulating hormone. In this review, epidemiological and clinical evidence and potential mechanisms underlying the proposed association between obesity and thyroid cancer risk are reviewed. If the association between obesity and thyroid cancer demonstrated in observational studies proves to be causal, targeting obesity (and/or downstream mediators of risk) could be of importance in the prevention and management of thyroid cancer.

Anthropometric Factors and Thyroid Cancer Risk by Histological Subtype: Pooled Analysis of 22 Prospective Studies

“…In cross-sectional studies, a greater BMI has been associated with higher thyroid cancer prevalence among individuals with screening-detected thyroid nodules (55) and increased tumor aggressiveness among overweight and obese papillary thyroid cancer patients (56,57). In a previous casecontrol study, greater BMI was associated with risk of thyroid cancers less than and greater than 10 mm in size (9).…”

Thyroid Volume and Its Relation to Anthropometric Measures in a Healthy Cuban Population

“…Hence, the mechanisms whereby obesity increases the risk of thyroid cancer are not clear and may be very complex with a synergistic action of different factors. Thyroid cancer risk may be mediated by hormonal changes and inflammation that result from adiposity [35,36,37]. The hypothesis is that obesity leads to hypoadiponectinemia, a proinflammatory state, and insulin resistance, which, in turn, leads to high circulating insulin and insulin-like growth factor-1 levels, thereby possibly increasing the risk for thyroid cancer.…”

“…The hypothesis is that obesity leads to hypoadiponectinemia, a proinflammatory state, and insulin resistance, which, in turn, leads to high circulating insulin and insulin-like growth factor-1 levels, thereby possibly increasing the risk for thyroid cancer. Thus, insulin resistance possibly plays a pivotal role in the observed association between obesity and thyroid cancer, potentially leading to the development and/or progression of thyroid cancer through its interconnections with other factors including insulin-like growth factor-1, adipocytokines/cytokines and thyroid-stimulating hormone [37]. …”

Current controversies in the initial post-surgical radioactive iodine therapy for thyroid cancer: a narrative review

“…Similarly, the increased incidence of DTC in the USA correlates with the rising prevalence of obesity (Di Cristofano 2013, Pazaitou-Panayiotou et al 2013). Populations with a high incidence of diabetes and obesity, such as those in South Texas (Duran-Gonzalez et al 2011), have a higher rate of DTC compared with the general USA population (Lopez et al 2013, Pappa & Alevizaki 2013.…”