Obesity and thyroid cancer

Abstract

Many studies have provided observational data on the association of obesity and thyroid cancers, but only few of them propose mechanisms that would permit a better understanding of the causal molecular mechanisms of this association. Considering that there is an increasing incidence of both obesity and thyroid cancers, we need to summarize and link recent studies in order to characterize and understand the contribution of obesity-related factors that might affect thyroid cancer development and progression. Adipose tissue is involved in many vital processes, including insulin sensitivity, angiogenesis, regulation of energy balance, activation of the complement system, and responses such as inflammation. Although these processes have their own molecular pathways, they involve the same molecules through which obesity and adipose tissue might exert their roles in carcinogenesis, not only affecting MAPK and PI3K or even insulin pathways, but also recruiting local inflammatory responses that could result in disease formation and progression. This review describes five important issues that might explain the link between excessive weight and thyroid cancer: thyroid hormones, insulin resistance, adipokines, inflammation, and sexual hormones.

Obesity, adipokines and cancer: an update

“…63 In differentiated thyroid cancer, however, the exact role of IL-6 remains to be elucidated. 42 In a Chinese community cohort in Hong Kong with a relatively low prevalence of obesity, we previously demonstrated central obesity predicted cancer development, and baseline IL-6 and soluble TNF receptor 2 levels were independent predictors of incident cancer development after a median interval of 9Á5 years, even after adjusting for conventional cancer risk factors.…”

“…16,41 Differentiated thyroid carcinoma, which included papillary thyroid carcinoma, was inversely associated with serum adiponectin levels. 42 In addition to the development of incident thyroid cancer, serum adiponectin levels also had implication in its prognosis. Patients with papillary thyroid carcinoma were more likely to have multicentric tumours, or tumours with extrathyroidal invasion and higher TNM stage if their tumour tissues were negative for both AdipoR1 and AdipoR2 expressions.…”

“…40 In differentiated thyroid cancers, the expression of leptin and its receptor was associated with a higher risk of lymph node metastases. 42 Moreover, leptin could affect the migration of thyroid cells, conferring higher metastatic potential and worse prognosis. 57 In the context of haematological malignancies, however, no positive associations were reported between leptin levels and multiple myeloma or non-Hodgkin lymphoma.…”

Autotaxin is an inflammatory mediator and therapeutic target in thyroid cancer

“…The role of individual cytokines such as IL1a, IL6 and IL17 has been documented in the growth of solid tumours such as pancreatic, gastric and colorectal cancers (Tjomsland et al 2013, Wang et al 2014, Li et al 2015. Despite an increasing appreciation for the role of inflammation in thyroid cancer progression, the connection between particular inflammatory signals and the potential for locally aggressive and metastatic papillary thyroid cancer variants is poorly understood (Cunha et al 2014a,b, Ehlers & Schott 2014, Marcello et al 2014, Provatopoulou et al 2014, Tafani et al 2014, Ward 2014.…”

Polymorphism inLEPandLEPRMay Modify Leptin Levels and Represent Risk Factors for Thyroid Cancer

“…Our group has previously demonstrated that cytokines produced by adipocytes (adipokines), such as adiponectin, leptin, and resistin, are differentially expressed in malignant and benign thyroid nodules, helping to differentiate not only malignancy but also subtypes of thyroid nodules, which are difficult to identify using PAAF [4]. Of the three adipokines, leptin presents as an interesting diagnostic option for thyroid malignancy; leptin has a 100% accuracy, as well as high sensitivity and specificity.…”