Obesity and excess protein and carbohydrate consumption are risk factors for thyroid cancer

Overweight as a biomarker for concomitant thyroid cancer in patients with Graves' disease

The incidence of concomitant thyroid cancer in Graves' disease varies and Graves' disease can make the diagnosis and management of thyroid nodules more challenging. Since the majority of Graves' disease patients primarily received non-surgical treatment, identifying biomarkers for concomitant thyroid cancer in patients with Graves' disease may facilitate planning the surgery. The aim of this study is to identify the biomarkers for concurrent thyroid cancer in Graves' disease patients and evaluate the impact of being overweight on cancer risk. This retrospective cohort study analyzed 122 patients with Graves' disease who underwent thyroid surgery at Seoul St. Mary's Hospital (Seoul, Korea) from May 2010 to December 2022. Body mass index (BMI), preoperative thyroid function test, and thyroid stimulating hormone receptor antibody (TR-Ab) were measured. Overweight was defined as a BMI of 25 kg/m² or higher according to the World Health Organization (WHO). Most patients (88.5%) underwent total or near-total thyroidectomy. Multivariate analysis revealed that patients who were overweight had a higher risk of malignancy (Odds ratios, 3.108; 95% confidence intervals, 1.196-8.831; p = 0.021). Lower gland weight and lower preoperative TR-Ab were also biomarkers for malignancy in Graves' disease. Overweight patients with Graves' disease had a higher risk of thyroid cancer than non-overweight patients. A comprehensive assessment of overweight patients with Graves' disease is imperative for identifying concomitant thyroid cancer.

Clinical characteristics and therapeutic response of differentiated thyroid carcinoma with obesity and diabetes

BACKGROUND

The effects of obesity and diabetes on the clinical outcomes of differentiated thyroid cancer (DTC) remain unclear.

OBJECTIVES

To explore the association between obesity and diabetes with pathological features and therapeutic response of DTC.

METHODS

Patients were categorized based on body mass index (BMI) and glycemic status. Compare the correlation between BMI and glycemic status with pathological features and therapeutic response of DTC. To analyze the independent risk factors for the aggressiveness of DTC.

RESULTS

The proportion of patients with bilateral tumors was higher in the overweight, obese and diabetes group (P = 0.001, 0.045). The overweight group demonstrated a higher TNM stage (P = 0.004), while the T and TNM stages were higher in the diabetes group (P = 0.032, 0.000). The probability of distant metastasis increases by 37.4% for each unit of BMI increase (odds ratio (OR) = 1.374, CI 95% 1.061-1.778, P < 0.05). The BMI of Biochemical Incomplete Response (BIR) is significantly higher than that of Excellent Response (ER) (P = 0.015), the fasting plasma glucose (FPG) of Structural Incomplete (SIR) was significantly higher than that of ER and BIR (P = 0.030, 0.014).

CONCLUSION

Obesity and diabetes have effect on DTC aggressiveness. BMI and FPG have correlation with the therapeutic response of DTC patients.

Effect of macadamia oil cake on blood lipid characteristics and intestinal microbiota in hyperlipidemic rat

Macadamia oil cake (MOC) is a type of macadamia nut by-product, that is extremely rich in amino acids and has beneficial health effects. It lowers blood lipid levels and regulates the intestinal microbiota. MOC effectively attenuated total cholesterol (TC), triglyceride (TG), low-density lipoprotein cholesterol (LDL-C), and high-density lipoprotein cholesterol (HDL-C) levels in model rats. Depending on the morphology of the colon, MOC can effectively attenuate damage to the tissue structure. The 16S rDNA gene of the rat intestinal microbiota was sequenced using Illumina PE250 high-throughput sequencing technology, and the changes in the intestinal microbiota in each group are discussed. Supplementing MOC at different doses significantly increased the microbiota of Dorea, Erysipelotrichaceae, Stercoris, etc. in the intestinal tracts of rats fed a high-fat diet. Therefore, MOC can be included in lipid healthy dietary patterns to lower lipid characteristics and restructure the intestinal microbiota. Future clinical trials are required to determine the therapeutic effects and mechanisms of hypolipidemia.

Dietary Approach of Patients with Hormone-Related Cancer Based on the Glycemic Index and Glycemic Load Estimates

Hormone-related cancers, namely breast, endometrial, cervical, prostate, testicular, and thyroid, constitute a specific group of cancers dependent on hormone levels that play an essential role in cancer growth. In addition to the traditional risk factors, diet seems to be an important environmental factor that partially explains the steadily increased prevalence of this group of cancer. The composition of food, the dietary patterns, the endocrine-disrupting chemicals, and the way of food processing and preparation related to dietary advanced glycation end-product formation are all related to cancer. However, it remains unclear which specific dietary components mediate this relationship. Carbohydrates seem to be a risk factor for cancer in general and hormone-related cancers, in particular, with a difference between simple and complex carbohydrates. Glycemic index and glycemic load estimates reflect the effect of dietary carbohydrates on postprandial glucose concentrations. Several studies have investigated the relationship between the dietary glycemic index and glycemic load estimates with the natural course of cancer and, more specifically, hormone-related cancers. High glycemic index and glycemic load diets are associated with cancer development and worse prognosis, partially explained by the adverse effects on insulin metabolism, causing hyperinsulinemia and insulin resistance, and also by inflammation and oxidative stress induction. Herein, we review the existing data on the effect of diets focusing on the glycemic index and glycemic load estimates on hormone-related cancers.

Food Intake of Patients with Thyroid Nodules: a Brazilian Food Guides-Based Analysis

Introduction: The thyroid gland has the function of secreting hormones that play an important role in metabolism. Alterations in this function may bring complications to individuals, among them thyroid nodules. The prevalence of thyroid nodules is higher in white people, older adults, women, smokers, with accumulated body fat and larger waist circumference. Objective: The aim of this study was to compare dietary intake of patients with benign (BN) and malignant (MN) thyroid nodules. Method: A cross-sectional study was conducted with 62 patients. Dietary intake was assessed using 24-hour dietary recall, according to the 2006 and 2014 Dietary Guidelines for the Brazilian Population. Mean consumption of each food group was compared between patients with BN and MN by Student’s t-test. Results: The sample consisted mostly of females with mean age of 43 years old. Based in the 2006 Guide, patients with BN and MN presented low consumption of fruits, vegetables, milk and dairy products, and high consumption of meat. Total caloric intake (p=0.03) and of the group of sugars and sweets (p=0.03) were higher among individuals with MN compared with BN. Considering the 2014 Guide, the highest caloric contribution for the diet was from minimally processed foods from minimally processed foods group. Conclusion: Patients with MN had higher energy intake of sugars and sweets. For all other food groups investigated, no significant difference between individuals with MN and BN was encountered.

Role of Dietary and Environmental Factors on Thyroid Cancer in Romania: A Brief Review

Thyroid cancer is the most common endocrine tumor, accounting for about 1% of all human malignancies. There are environmental factors that can potentiate the onset of thyroid cancer, in particular pollutants, lifestyle or radiation exposure. Another major cause responsible for the appearance of thyroid cancer is the habitat in endemic areas where there is a deficit of iodine in the soil, drinking water and food. We operated using the PubMed database in order to find the articles of interest. After a wary review of the literature, we designated the relevant articles necessary for our study including various factors such as alimentation, effects of the Chernobyl fallout radiation and the iodine and vitamin D deficiency in Romania. The aim of this article is to make a correlation between the different environmental and dietary factors in Romania, and the increased incidence of thyroid cancer.

The association of obesity with thyroid carcinoma risk

Background

The prevalence of obesity and an increased incidence of thyroid carcinoma (TC) threaten public health in parallel on a global scale. Sufficient evidence supports excess body fatness in thyroid carcinogenesis, and the role and anthropometric markers of obesity have been causally associated with the rising risk of TC.

Methods

A literature search was conducted in PubMed. Studies focused on the effect of obesity in TC.

Results

This review mainly discusses the global incidence and prevalence of obesity‐related TC. We also review the role of obesity in TC and potential clinical strategies for obesity‐related TC.

Conclusions

Excess body fatness in early life and TC survival initiate adverse effects later in life.

The incidence of thyroid cancer has been increasing in the last decades all over the world. Such a steady growth cannot be entirely attributable to more sensitive diagnostic procedures. Obesity has increased with sufficient rapidity in the same time frame and may as possible promoters and modifiable risk factors for thyroid cancer in recent years. The aim of this review was to focus on the relationship between obesity and the risk of thyroid cancer. Obesity seems to play a relevant role in thyroid cancer carcinogenesis as well as in its severity and aggressiveness. The possible underlying mechanism is involved chronic inflammation mediated by cytokines, leptin, and adiponectins.

Effects of concomitant obesity and diabetes on the aggressiveness and outcomes of differentiated thyroid cancer patients

OBJECTIVE

Obesity and diabetes are the risk factors for cancer development including differentiated thyroid cancer (DTC). Contradictory accumulated data indicates the possible negative effects of obesity and hyperglyceamia as a factor for aggressiveness of DTC. The aim of the present study is to investigate the association of high body mass index (BMI) and presence of type 2 diabetes mellitus (T2DM) on the histological aggressiveness and clinical outcomes in DTC patients followed for over 4 years in a single center.

METHODS

Consequative 526 DTC patients who had undergone total thyroidectomy and/or radioactive iodine (RAI) ablation were reviewed retrospectively. Patients were divided into groups based on their BMI: normal weight, overweight, obese and also were evalauted in 3 groups presence of diabetes, prediabetes and nomoglyceamia. Histological aggressiveness of DTC at the time of diagnosis and clinical response at the time of last clinical visit were reassessed according to the criteria suggested by ATA 2015 guideline.

RESULTS

No differences in histopathologic features, risk of recurrence, cumulative dose of RAI ablation and prevalence of 131I avid metastatic disease were demonstrated among the groups both classified according to BMI and hyperglycemia. Mean of 3.4 year follow-up also showed no differences in the clinial repsonse to therapy and percentage of nonthyroid primary cancer in DTC patients.

CONCLUSION

In this retrospective study we demonstrated that obesity and T2DM have no additive effect on DTC aggressiveness and response to therapy. DTC patients with obesity and diabetes can be treated according to present guidelines without requirement for spesific attention.

Effect of Cigarette Smoking on Thyroid Cancer: Meta-Analysis

BACKGROUND

Although smoking is generally carcinogenic, its effect on thyroid cancers is still subject to controversy. The purpose of this study was to summarize the role of smoking in relation to thyroid cancer occurrence.

METHODS

We performed a meta-analysis of 24 eligible studies: 21 case-control studies and three prospective cohort studies. The summary odds ratio (OR) and 95% confidence interval (CI) of all studies were acquired based on random effect model. Further subgroup analyses were conducted according to gender, histological type of thyroid cancer, and smoking status of patients for the case-control studies.

RESULTS

The summary effect size indicated a negative association of smoking for thyroid cancer (OR, 0.798; 95% CI, 0.681 to 0.935). From the subgroup analyses for the case-control studies, reduced risk of thyroid cancer was observed in both men (OR, 0.734; 95% CI, 0.553 to 0.974) and women (OR, 0.792; 95% CI, 0.700 to 0.897). The protective effect of smoking was observed in studies in which thyroid cancer was limited to differentiated thyroid cancers (DTCs) (OR, 0.798; 95% CI, 0.706 to 0.902).

CONCLUSION

Our results suggests that smoking may have a protective effect on thyroid cancer, especially on DTCs. Further studies with larger sample sizes should be conducted in elucidating the dose and time dependent effect of smoking on thyroid cancer with specific focus on the types of thyroid cancers.

Association of Polygenetic Risk Scores Related to Cell Differentiation and Inflammation with Thyroid Cancer Risk and Genetic Interaction with Dietary Intake

Simple Summary

Global thyroid cancer incidence is increasing, especially in women. Genetic and environmental factors mutually contribute to its incidence. We aimed to identify genetic variants to influence thyroid cancer risk and determine their interactions with lifestyles in a large city hospital-based cohort (495 thyroid cancer patients and 56,439 control). The best polygenetic model included DIRC3_rs6759952, GAP43_rs13059137, NRG1_rs7834206, PROM1_rs72616195, LRP1B_rs1369535, and LOC100507065_rs11175834, tumorigenesis and cancer cell differentiation-related genes. Their high polygenetic risk scores (PRS) increased thyroid cancer risk by 3.90-fold compared to low-PRS. Thyroid cancer risk was elevated in females, high white blood cell counts, and high energy, low alcohol, and high seaweed intakes by 4.21, 4.03, 7.00, 4.11, and 4.02-fold, respectively. These factors interacted with PRS: the women with high-PRS elevated thyroid cancer risk much among women with high daily energy, seaweeds, and alcohol intake. These results could be applied to personalized nutrition plans to reduce thyroid cancer risk.

Abstract

The incidence of thyroid cancer continues to increase steadily, and this increasing incidence cannot be attributed solely to the overdiagnosis of microcarcinoma or technical advancements in detection methods and may also depend on environmental and genetic factors. However, the impacts and interactions of genetic and environmental factors remain controversial, and they may differ in Eastern and Western countries. The study’s purpose was to identify single nucleotide polymorphisms of genes related to cell differentiation and inflammation to influence thyroid cancer incidence and determine interactions with lifestyles in a large city hospital-based cohort. Genetic variants were selected by genome-wide association study with thyroid cancer participants (case; n = 495) and controls without cancers (n = 56,439). SNPs having gene–gene interactions were selected by generalized multifactor dimensionality reduction. Polygenic risk scores (PRSs) were generated by summing the number of selected SNP risk alleles. PRSs of the best model included 6 SNPs, that is, DIRC3_rs6759952, GAP43_rs13059137, NRG1_rs7834206, PROM1_rs72616195, LRP1B_rs1369535, and LOC100507065_rs11175834. Participants with a high-PRS had a higher thyroid cancer risk by 3.9-fold than those with a low-PRS. The following variables were related to an increased thyroid cancer risk; female (OR = 4.21), high white blood cell count (OR = 4.03), and high energy (OR = 7.00), low alcohol (OR = 4.11), and high seaweed (OR = 4.02) intakes. These variables also interacted with PRS to influence thyroid cancer risk. Meat/noodle diet patterns interacted with PRSs to increase thyroid cancer risk (p = 0.0023). In conclusion, women with a high-PRS associated with cell differentiation and inflammation were at an elevated thyroid cancer risk. Daily energy, seaweeds, and alcohol intake interacted with PRS for thyroid cancer risk. These results could be applied to personalized nutrition plans to reduce the risk of thyroid cancer.

Obesity and the prevention of thyroid cancer: Impact of body mass index and weight change on developing thyroid cancer - Pooled results of 24 million cohorts

BACKGROUND

Body weight may be a modifiable risk factor predisposing to different cancers. To establish a potential impact of weight change on thyroid cancer risk, we conducted a meta-analysis to evaluate the effect of body mass index (BMI) and weight change over time as a risk of developing thyroid cancer (TC).

METHODS

A systematic search was performed up to February 25, 2020. Pooled relative risk (RR) were estimated using fixed and random models. Heterogeneity between articles was examined using Q-test and I² index. Evaluation of publication bias was conducted with Egger's regression test.

RESULTS

A total of 31 studies including 24,489,477 cohorts were eligible. Pooled analysis revealed that normal and underweight cohorts were associated with a decreased risk of TC (RR = 0.68, 95%CI = 0.65-0.71, p < 0.001) and (RR = 0.92, 95%CI = 0.91-0.93, p < 0.001), respectively. In contrast, overweight and obese cohorts were more likely to develop TC (RR = 1.26, 95%CI = 1.24-1.28, p < 0.001 and RR = 1.50, 95%CI = 1.45-1.55, p < 0.001, respectively). Obesity was associated with higher risk of developing TC among women (RR = 1.29, 95%CI = 1.14-1.46, p < 0.001), but not men (RR = 1.25, 95%CI = 0.97-1.62, p = 0.08). Furthermore, weight gain increased the risk of developing TC (RR = 1.18, 95%CI = 1.14-1.22, p < 0.001), while weight loss decreased the risk (RR = 0.89, 95%CI = 0.85-0.93, p < 0.001). Results showed similar trends of weight change effect in both males and females.

CONCLUSIONS

Obesity is associated with higher risk of developing TC in women. However, maintaining a healthy weight is associated with reduced risk of TC in both women and men. Shifting our practice to include weight control strategies will help lead to cancer prevention.

Nutritional status and follicular-derived thyroid cancer: An update

The incidence of differentiated thyroid cancer has been increasing in the last decades all over the world. Such a steady growth cannot be entirely attributable to more intensive thyroid nodule screening and more sensitive diagnostic procedures. Several environmental factors have changed with sufficient rapidity in the same time frame and may represent credible candidates for this increase. They include modified iodine intake, lifestyle-associated risk factors, exposure to various toxic compounds, pollutants and xenobiotics, nutritional deficiencies, eating habits and comorbidities. Foremost, nutritional patterns have gained high interest as possible promoters and modifiable risk factors for thyroid cancer in recent years. The aim of this narrative review is to focus on the relationship between thyroid cancer and nutritional factors, dietary habits and obesity. Low iodine intake has been associated to increased risk of thyroid cancer, favoring the development of more aggressive histotypes. Moreover, correction of iodine deficiency can shift thyroid cancer subtypes toward less aggressive forms, without affecting the overall risk for cancer. Actually, evidence regarding the association between selenium and vitamin D deficiency and thyroid cancer is very limited, despite their well-known anti-cancer potentials, and the clinical usefulness of their supplementation is still uncertain in this setting. Albeit the relationship between single foods and thyroid cancer is difficult to examine, fish and iodine-rich foods, vegetables, and fruits might exert protective effects on thyroid cancer risk. Conversely, no clear association has been found for other foods to date. Lastly, a clear association between obesity and the risk of thyroid cancer, with more aggressive behavior, seems to emerge from most studies, likely involving variations in thyroid function and chronic inflammation mediated by cytokines, insulin, leptin and adiponectins. Although no definite association between dietary factors and thyroid cancer has been firmly established so far, some nutritional patterns, together with excessive weight, seem to play a relevant role in thyroid cancer carcinogenesis as well as in its severity and aggressiveness. These effects may play an additive role to the well-established one exerted by environmental carcinogens, such as pollutants and radiation exposure.

Weight change is significantly associated with risk of thyroid cancer: A nationwide population-based cohort study

Obesity is a risk factor for many cancers including breast, esophageal, colon, and thyroid cancer. We aimed to evaluate the association of thyroid cancer with body mass index (BMI), waist circumference (WC), and weight change. This nationwide population-based cohort study included 11,323,006 adults who joined the national health screening program. Weight change was defined as the difference between the weight of the subjects measured during the study period and the weight at the time of four years ago. For evaluating the association between the weight change and the risk of thyroid cancer, subjects without weight change for four years were defined as the reference group. Mean age was 50.1 ± 13.7 years and 44% were female. In total, 50,464 subjects (0.4%) had newly-diagnosed thyroid cancer. After multivariable analyses, the incidence of thyroid cancer increased significantly in subjects with larger WC as well as higher BMI (P < 0.001 and P < 0.001, respectively). In subjects who were lean and became obese, the incidence of thyroid cancers increased significantly (hazard ratio [HR] 1.15 [1.11-1.19]). In subjects who were obese and became lean, the incidence of thyroid cancers decreased significantly (HR 0.89 [0.86-0.93]). These results demonstrated that higher BMI and larger WC were significantly associated with an increased risk of thyroid cancer. Weight gain in lean subjects was associated with an increased risk of thyroid cancer, and weight reduction in subjects with obesity was associated with a decreased risk of thyroid cancer.

Nutritional and Environmental Factors in Thyroid Carcinogenesis

Several epidemiological studies suggest an increased incidence of thyroid carcinoma (TC) in recent years, especially for the papillary histotype (PTC), suggesting that specific carcinogens might promote molecular abnormalities that are typical of PTC. The increased incidence is probably attributed to more intensive and sensitive diagnostic procedures, even if recent data suggest that various toxic elements could explain the phenomenon. Ionizing radiation exposure represents the most accepted risk factor for differentiated thyroid cancer that includes both the follicular and papillary histotypes. In this review, we examined the other environmental carcinogens that play a role in TC, such as eating habits, living in volcanic areas, and xenobiotic elements. Among eating habits, iodine intake represents one of the more discussed elements, because its deficiency is associated with follicular thyroid carcinomas (FTCs), while its progressive increment seems to be responsible for PTC. The gas, ash, and lava emissions of volcanoes are composed of various toxic compounds that pollute ground water, vegetables, and animals, contaminating humans via the food chain. Finally, the risk of developing PTC has also been associated with exposure of the population to xenobiotics in the environment or in the home. Their carcinogenic effects are probably caused by their accumulation, but additional studies are necessary to better understand the mechanisms of action.

The association between thyroid cancer and insulin resistance, metabolic syndrome and its components: A systematic review and meta-analysis

BACKGROUND

Thyroid cancer is rapidly increasing in incidence worldwide in the past several decades, same as the incidence of metabolic syndrome. We performed a system review and meta-analysis of the association between metabolic syndrome, its components and insulin resistance and thyroid cancer incidence.

METHODS

We searched several computer-assisted databases PUBMED, EMBASE and ISI Web of Science to identify studies published before 31st January 2018. Every study must report either risk estimates of thyroid cancer incidence with 95% confidence interval (CI) or related data can speculate. Two investigators independently identified eligible studies and extracted data. Evaluating the summaries of relative risk estimates use both fixed and random effects methods.

RESULTS

We found 42 articles met the inclusion criteria of this review. There is an increased risk for thyroid cancer for patients with insulin resistance (relative risk [RR] = 1.59, 95%confidence interval [CI] = 1.12-2.27, P = 0.01), dysglycemia (RR = 1.40, 95%CI = 1.15-1.70,P < 0.001), high BMI (RR = 1.35,95%CI = 1.23-1.48,P < 0.001) and hypertension(RR = 1.34,95%CI = 1.22-1.47, p < 0.001). However, patients with dyslipidemia, both total cholesterol (RR = 1.09, 95%CI = 0.98-1.21, P = 0.13) and triglyceride (RR = 1.01, 95%CI = 0.91-1.12, P = 0.82) was not associated with thyroid cancer.

CONCLUSIONS

Our meta-analysis showed Insulin Resistance, dysglycemia, high BMI and hypertension significantly increased the thyroid cancer risk. These results may help identify people with high risk of thyroid cancer and change to healthy life style.

Association between Height and Actinic Keratosis: A Nationwide Population-based Study in South Korea

The association between actinic keratosis (AK) and anthropometric measures has not been investigated. This study aims to evaluate the associations between anthropometric measures and the incidence of AK in South Korea. We analyzed clinical data from individuals aged over 20 years who received a health examination arranged by the national insurance program between 2005 and 2008. Newly diagnosed AK was identified using claims data from baseline to the date of diagnosis or until December 31, 2015. The incidence of AK was highest among the elderly (aged over 60 years) and showed a male bias. The risk of AK increased with greater height. The quintile with the greatest height had an increased risk of AK compared with the quintile with the lowest height (hazard ratio = 1.28, 95% confidence interval: 1.24-1.33) after adjustment for age, sex, income, smoking status, alcohol consumption, hypertension, dyslipidemia, myocardial infarction, congestive heart failure, and chronic obstructive pulmonary disease. This study showed a positive association between the incidence of AK and human height. However, it is unclear whether these findings can be generalized to Koreans who have not received an examination or to populations in other countries.

Association of Obesity and Thyroid Cancer at a Tertiary Care Hospital in Pakistan

Objective

Thyroid cancer (TC) is one of the most common endocrine malignancies with a rapidly increasing worldwide presence. In Pakistan, it is more prevalent in females than males and has an incidence rate of 2.1%. Obesity and excess body mass index (BMI) has been linked to several cancers and is thought to be a risk factor for TC. We aim to investigate the incidence of TC in our population and understand it’s correlation with obesity.

Subjects

The study was a retrospective case series conducted in the years 2000 to 2014, at the Aga Khan University Hospital (AKUH), Karachi, Pakistan where 156 patients who had been diagnosed and treated for TC were analyzed. Clinicopathological data was collected from medical records of these patients and weight and height were measured, pre-surgery, post-surgery, and at follow up. The BMI was correlated with patient variables for any significant associations.

Results

The patient set comprised of 38.5% males and 61.5% females with a mean age of 47.77 (SD ± 14.35). The BMI was significantly associated with age as 72.8% of participants were obese and >45 years old as compared to 27.2% who were under 45 years and obese (p-value <0.001). Upon comparison of the pre-surgery, post-surgery, and current mean BMI, Bonferroni pairwise comparisons showed no significant difference (p>0.999).

Conclusion 

The majority of-of TC patients among the Pakistani population were obese and female. Age was significantly associated with the risk of having a higher BMI. Moreover, differences in BMI pre and post-surgery could not be statistically proven.

Serum interleukin measurement may help identify thyroid cancer patients with active disease

BACKGROUND

Investigate the clinical utility of serum interleukin dosages of IL-2, IL-2R, IL-4, IL-6, IL-6R, IL-8, IL-10 and IL-12 in the diagnosis and characterization of patients with DTC. In particular, verify ILs utility in the identification of individuals who are evolving disease-free or with the active disease.

METHODS

We evaluated 200 patients with malignant nodules (100 patients disease-free and 100 patients with recurrence/active disease); 60 benign nodules and 100 healthy controls, serum levels were assessed by ELISA.

RESULTS

All ILs, but not IL-4, differentiated these three groups. We observed that IL-2, 2R and 10 serum concentrations were associated with thyroglobulin levels. Serum IL-2 was able to differentiate patients with active disease from the disease-free with a sensitivity of 98%, specificity of 58%, positive predictive value (PPV) of 70% and negative predictive value (NPV) of 97% (p=0.0007). IL-6R levels differentiated patients with active disease from the disease-free patients with 56% sensitivity, 63% specificity, PPV of 60% and NPV of 59% (p<0.0001). IL-8 values also distinguished patients with active disease from the disease-free ones with sensitivity of 50%, specificity of 76%, PPV of 68% and NPV of 60% (p=0.0025); using IL-12, we obtained a sensitivity value of 73%, specificity of 66%, PPV of 68% and NPV of 71% (p<0.0001). Furthermore, interleukin levels showed association with some tumor characteristics of aggressiveness.

CONCLUSION

We suggest that the serum concentration of ILs may assist in the diagnosis and characterization of tumor malignancy helping identify patients with active disease who deserve closer medical attention.

Oncogenesis of Thyroid Cancer

Thyroid neoplasms encompass a variety of lesions that range from benign adenomas to malignancies. These latter can be well-differentiated, poorly differentiated or undifferentiated (anaplastic) carcinomas. More than 95% of thyroid cancers are derived from thyroid follicular cells, while 2-3% (medullary thyroid cancers, MTC) originate from calcitonin producing C-cells. Over the last decade, investigators have developed a clearer understanding of genetic alterations underlying thyroid carcinogenesis. A number of point mutations and translocations are involved, not only in its tumorigenesis, but also as have potential use as diagnostic and prognostic indicators and therapeutic targets. Many occur in genes for several important signaling pathways, in particular the mitogen-activated protein kinase (MAPK) pathway. Sporadic (isolated) lesions account for 75% of MTC cases, while inherited MTC, often in association with multiple endocrine neoplasia (MEN) type 2A and 2B syndromes, constitute the remainder. However, non-MEN familial MTC may also occur. Advances in genetic testing have revolutionized the management of MTC, with prospects of genetic screening, testing and early prophylactic thyroidectomy. Ethical concerns of these advances are addressed.

Obesity Does Not Modify the Risk of Differentiated Thyroid Cancer in a Cytological Series of Thyroid Nodules

BACKGROUND

A possible impact of obesity on the risk of thyroid cancer has been postulated in some studies, but it remains controversial.

OBJECTIVE

To investigate the association between obesity and differentiated thyroid carcinoma in a population of unselected patients subjected to fine-needle aspiration cytology (FNAC) for thyroid nodules.

METHODS

We retrospectively evaluated the results of FNAC of thyroid nodules in 4,849 patients (3,809 females and 1,040 males; mean age 55.9 ± 14.1 years). Patients were stratified according to their body mass index (BMI). There were 1,876 (38.7%) normal-weight patients (BMI 18-24.9), 1,758 (36.2%) overweight (BMI 25-29.9), 662 (13.7%) grade 1 obese (BMI 30-34.9), 310 (6.4%) grade 2 obese (BMI 35-39.9) and 243 (5.0%) grade 3 obese (BMI >40).

RESULTS

The prevalence of suspicious or malignant nodules (Thy4/Thy5) did not differ across the 5 BMI groups, i.e. it was 6.8% in normal-weight patients, 6.3% in overweight patients, 6.3% in grade 1 obese patients, 4.0% in grade 2 obese patients and 4.2% in grade 3 obese patients (p = 0.29). The prevalence of Thy4/Thy5 nodules did not differ when males and females were evaluated separately (p = 0.22 and p = 0.12, respectively). A significant, lower rate of Thy4/5 cytology was observed in female patients with grade 2-3 obesity (odds ratio 0.51; 95% confidence interval 0.284-0.920; p = 0.009).

CONCLUSIONS

The results of this study, in a retrospective series of patients with thyroid nodules, do not confirm previous findings reporting an association between obesity and differentiated thyroid carcinoma. Thus, obese patients with nodular thyroid disease should be managed the same as normal-weight patients.

Energy and macronutrient intake and risk of differentiated thyroid carcinoma in the European Prospective Investigation into Cancer and Nutrition study

Incidence rates of differentiated thyroid carcinoma (TC) have increased in many countries. Adiposity and dietary risk factors may play a role, but little is known on the influence of energy intake and macronutrient composition. The aim of this study was to investigate the associations between TC and the intake of energy, macronutrients, glycemic index (GI) and glycemic load in the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort. The study included 477,274 middle-age participants (70.2% women) from ten European countries. Dietary data were collected using country-specific validated dietary questionnaires. Total carbohydrates, proteins, fats, saturated, monounsaturated and polyunsaturated fats (PUFA), starch, sugar, and fiber were computed as g/1,000 kcal. Multivariable Cox regression was used to calculate multivariable adjusted hazard ratios (HR) and 95% confidence interval (CI) by intake quartile (Q). After a mean follow-up time of 11 years, differentiated TC was diagnosed in 556 participants (90% women). Overall, we found significant associations only with total energy (HRQ4 vs .Q1 , 1.29; 95% CI, 1.00-1.68) and PUFA intakes (HRQ4 vs .Q1 , 0.74; 95% CI, 0.57-0.95). However, the associations with starch and sugar intake and GI were significantly heterogeneous across body mass index (BMI) groups, i.e., positive associations with starch and GI were found in participants with a BMI ≥ 25 and with sugar intake in those with BMI < 25. Moreover, inverse associations with starch and GI were observed in subjects with BMI < 25. In conclusion, our results suggest that high total energy and low PUFA intakes may increase the risk of differentiated TC. Positive associations with starch intake and GI in participants with BMI ≥ 25 suggest that those persons may have a greater insulin response to high starch intake and GI than lean people.

Adiposity and risk of thyroid cancer: a systematic review and meta-analysis

Thyroid cancer incidence has increased rapidly over time, as has obesity prevalence. A link between the two appears plausible, but the relation of adiposity to thyroid cancer remains incompletely understood. We performed a meta-analysis of adiposity measures and thyroid cancer using studies identified through October 2014. Twenty-one articles yielded data on 12,199 thyroid cancer cases. We found a statistically significant 25% greater risk of thyroid cancer in overweight individuals and a 55% greater thyroid cancer risk in obese individuals as compared with their normal-weight peers. Each 5-unit increase in body mass index (BMI), 5 kg increase in weight, 5 cm increase in waist or hip circumference and 0.1-unit increase in waist-to-hip ratio were associated with 30%, 5%, 5% and 14% greater risks of thyroid cancer, respectively. When evaluated by histologic type, obesity was significantly positively related to papillary, follicular and anaplastic thyroid cancers, whereas it revealed an inverse association with medullary thyroid cancer. Both general and abdominal adiposity are positively associated with thyroid cancer. However, relations with BMI vary importantly by tumour histologic type.

Higher body mass index and larger waist circumference may be predictors of thyroid carcinoma in patients with Hürthle-cell lesion/neoplasm fine-needle aspiration diagnosis

OBJECTIVE

High body mass index (BMI) has been found to be associated with raised thyroid cancer risk, particularly in women. We examined the associations for BMI and waist circumference (WC) with thyroid cancer risk among women with Hürthle-cell lesion/neoplasm (HLN) on fine-needle aspiration biopsy (FNAB) with the hypothesis that BMI and WC could guide the management of these challenging indeterminate lesions.

METHODS

This cross-sectional study included 224 women with HLN who underwent thyroidectomy. In all patients, TSH and thyroid auto-antibodies were evaluated, and thyroid nodule features were recorded. Patients were grouped according to BMI (<30 or ≥30 kg/m(2)) and WC (<88 or ≥88 cm). Relationships of thyroid cancer with BMI and WC were assessed using logistic regression analysis.

RESULTS

Mean weight, BMI (31·26 ± 5·1 vs 26·47 ± 5·9, P < 0·001), WC (98·23 ± 7·6 vs 86·18 ± 11, P = 0·001), and proportion of patients with high BMI (≥30 kg/m(2)) (65·9 vs 33·8%, P < 0·001) or large WC (≥88 cm) (84·1 vs 47·9%, P < 0·001) were significantly higher in malignant group compared to benign group. In regression analysis, BMI and WC significantly associated with existence of malignancy. Malignancy risk was 3·819-fold higher (95% CI: 2·068-7·054) in BMI≥30 kg/m(2) group compared to BMI<30 kg/m(2), which was independent of TSH and age. Large WC was also associated with increased risk (OR = 5·593, 95% CI: 2·736-11·434). Baseline tumour characteristics were similar according to BMI and WC groups.

CONCLUSIONS

A great BMI and large WC were associated with higher thyroid cancer risk in patients with FNAB diagnosis of HLN. Further studies are needed to use BMI or WC in the management of patients with HLN.

Lack of Associations between Body Mass Index and Clinical Outcomes in Patients with Papillary Thyroid Carcinoma

BACKGROUND

Obesity is associated with aggressive pathological features and poor clinical outcomes in breast and prostate cancers. In papillary thyroid carcinoma (PTC), these relationships remain still controversial. This study aimed to evaluate the associations between body mass index (BMI) and the clinical outcomes of patients with PTC.

METHODS

This retrospective study included 1,189 patients who underwent total thyroidectomy for PTCs equal to or larger than 1 cm in size. Clinical outcomes were evaluated and compared based on the BMI quartiles.

RESULTS

There were no significant associations between BMI quartiles and primary tumor size, extrathyroidal invasion, cervical lymph node metastasis, or distant metastasis. However, an increase in mean age was associated with an increased BMI (P for trend <0.001). Multifocality and advanced tumor-node-metastasis (TNM) stage (stage III or IV) were significantly associated with increases of BMI (P for trend 0.02 and <0.001, respectively). However, these associations of multifocality and advanced TNM stage with BMI were not significant in multivariate analyses adjusted for age and gender. Moreover, there were no differences in recurrence-free survivals according to BMI quartiles (P=0.26).

CONCLUSION

In the present study, BMI was not associated with the aggressive clinicopathological features or recurrence-free survivals in patients with PTC.

Relationship between obesity, diabetes and the risk of thyroid cancer

PURPOSE

Analyze the relationship between obesity and type-2 diabetes mellitus (DM) and the development of differentiated thyroid cancer (DTC).

MATERIALS AND METHODS

A randomized case-controlled retrospective chart review of outpatient clinic patients at an academic medical center between January 2005 and December 2012. DTC patients were compared to two control groups: primary hyperparathyroidism (PHPTH) patients with euthyroid state and Internal Medicine (IM) patients. Exposure variables included historical body-mass-index (BMI), most recent BMI within 6 months and DM. Multivariate logistic regressions adjusting for gender, age, and year of BMI assessed the adjusted Odds Ratio (OR) of DTC with both BMI and DM.

RESULTS

Comparison of means showed a statistically significant higher BMI in DTC (BMI=37.83) than PHPTH, IM, and pooled controls, BMI=30.36 p=<0.0001, BMI=28.96 p=<0.0001, BMI=29.53 p=<0.0001, respectively. When compared to PHPTH, DM was more frequent in DTC (29% vs. 16%) and prevalence trended towards significance (p=0.0829, 95% CI =0.902-5.407). BMI adjusted OR was significant when compared to PHPTH, IM and pooled controls: 1.125 (p=0.0001), 1.154 (p=<0.0001), and 1.113 (p=<0.0001), respectively. DM adjusted OR was significant when compared to PHPTH and pooled controls at 3.178 (95% 1.202,8.404, p=0.0198) and 2.237 (95% 1.033,4.844, p=0.0410), respectively.

CONCLUSION

Our results show that obesity and, to a lesser degree, DM are significantly associated with DTC. BMI in particular was a strong predictive variable for DTC (C=0.82 bivariate, C=0.84 multivariate).

Increasing incidence of thyroid cancer in the Commonwealth of Pennsylvania

IMPORTANCE

The incidence of thyroid cancer in the United States has increased rapidly and Pennsylvania is the state with the highest rate of thyroid cancer in the country, although the factors driving this increase are unknown. Moreover, it remains unclear whether the increase in thyroid cancer represents a true increase in disease or is the result of overdiagnosis.

OBJECTIVE

To compare the increase in thyroid cancer incidence and tumor characteristics in Pennsylvania with the rest of the United States and gain insight into the factors influencing the increased incidence of thyroid cancer.

DESIGN, SETTING, AND PARTICIPANTS

In a population-based study, data on thyroid cancer from the Surveillance Epidemiology and End Results 9 (SEER-9) registry and the Pennsylvania Cancer Registry (PCR) from 1985 through 2009 were collected and reviewed for information regarding sex, race, histologic type of thyroid cancer, staging, and tumor size at diagnosis. International Classification of Diseases for Oncology, Third Edition code C739 (thyroid carcinoma) was used to identify 110,615 records in the SEER-9 registry and 29,030 records in the PCR.

MAIN OUTCOMES AND MEASURES

Average annual percent change (AAPC) in thyroid cancer incidence across various demographic groups in Pennsylvania.

RESULTS

The AAPC for thyroid cancer in Pennsylvania was 7.1% per year (95% CI, 6.3%-7.9%) vs 4.2% (95% CI, 3.7%-4.7%) per year in the remainder of the United States, and trends in incidence were significantly different (P < .001). Females experienced a higher AAPC (7.6% per year; 95% CI, 6.9%-8.3%) compared with males (6.1% per year; 95% CI, 4.9%-7.2%) (P < .01), and trend analysis revealed that thyroid cancer may be increasing more rapidly among black females (8.6% per year; 95% CI, 5.4%-11.9%) than among white females (7.6% per year; 95% CI, 6.8%-8.4) (P = .60; but despite the similarity in AAPC between the 2 groups, the joinpoint models fit to the data were not parallel [P < .005]). The rate of tumors with regional (7.0% per year; 95% CI, 5.8%-8.1%) or distant (1.1% per year; 95% CI, 0.3%-1.8%) spread (P < .05) and tumors that were 2 to 4 cm (7.1% per year; 95% CI, 5.2%-9.0%) (P < .05) or larger than 4 cm (6.4% per year; 95% CI, 4.5%-8.2%) (P < .05) at diagnosis also increased.

CONCLUSIONS AND RELEVANCE

The incidence of thyroid cancer is rising at a faster rate in Pennsylvania than in the rest of the nation, as is the rate of tumors that are larger and higher stage at diagnosis. These findings suggest that rising disease burden has contributed to the increased incidence of thyroid cancer. Etiologic factors promoting the rise in thyroid cancer in Pennsylvania must be investigated and may provide insight into the drivers of the national increase in thyroid cancer.

Obesity and risk of thyroid cancer: evidence from a meta-analysis of 21 observational studies

BACKGROUND

Several studies have evaluated the association between obesity and thyroid cancer risk. However, the results remain uncertain. In this study, we conducted a meta-analysis to assess the association between obesity and thyroid cancer risk.

MATERIAL/METHODS

Published literature from PubMed, EMBASE, Springer Link, Ovid, Chinese Wanfang Data Knowledge Service Platform, Chinese National Knowledge Infrastructure (CNKI), and Chinese Biology Medicine (CBM) were retrieved before 10 August 2014. We included all studies that reported adjusted risk ratios (RRs), hazard ratios (HRs) or odds ratios (ORs), and 95% confidence intervals (CIs) of thyroid cancer risk.

RESULTS

Thirty-two studies (n=12 620 676) were included in this meta-analysis. Obesity was associated with a significantly increased risk of thyroid cancer (adjusted RR=1.33; 95% CI, 1.24-1.42; I2=25%). In the subgroup analysis by study type, increased risk of thyroid cancer was found in cohort studies and case-control studies. In subgroup analysis by sex, both obese men and women were at significantly greater risk of thyroid cancer than non-obese subjects. When stratified by ethnicity, significantly elevated risk was observed in Caucasians and in Asians. In the age subgroup analysis, both young and old populations showed increased thyroid cancer risk. Subgroup analysis on smoking status showed that increased thyroid cancer risks were found in smokers and in non-smokers. In the histology subgroup analyses, increased risks of papillary thyroid cancer, follicular thyroid cancer, and anaplastic thyroid cancer were observed. However, obesity was associated with decreased risk of medullary thyroid cancer.

CONCLUSIONS

Our results indicate that obesity is associated with an increased thyroid cancer risk, except medullary thyroid cancer.

Polymorphism in LEP and LEPR May Modify Leptin Levels and Represent Risk Factors for Thyroid Cancer

Purpose. To understand the role of polymorphisms in the LEP (rs7799039 and rs2167270) and LEPR (rs1137101 and rs1137100) genes in DTC susceptibility and their effect on leptin levels. Methods. We studied 153 patients with DTC and 234 controls through TaqMan SNP Genotyping and ELISA, comparing these data to the clinicopathological data of patients with DTC. Results. Patients with AA genotype of rs7799039 had higher levels of serum leptin (9.22 ± 0.98 ng/mL) than those with AG genotype (10.07 ± 0.60 ng/mL; P = 0.005). Individuals with AG genotype of rs2167270 also produced higher serum leptin levels (10.05 ± 0.59 ng/mL) than the subjects with GG genotype (9.52 ± 0.79 ng/mL; P < 0.05). A multivariate logistic regression adjusted for gender, age, and BMI showed that the AG genotype of rs7799039 was an independent risk for DTC (OR, 11.689; P = 0.0183; 95% CI, 1.516-90.119). Similarly, AG and GG genotypes of rs1137101 increased the susceptibility to DTC (OR, 3.747; P = 0.027; 95% CI, 1.161-12.092 and OR, 5.437; P = 0.013; 95% CI, 1.426-20.729). Conclusions. We demonstrated that rs7799039 and rs2167270 polymorphisms modify the serum leptin concentrations in patients with DTC. Furthermore, polymorphisms rs7799039 and rs1137101 increase the risk of DTC development, although they do not correlate with tumor aggressiveness.

The influence of the environment on the development of thyroid tumors: a new appraisal

Most epidemiological studies concerning differentiated thyroid cancers (DTC) indicate an increasing incidence over the last two decades. This increase might be partially explained by the better access to health services worldwide, but clinicopathological analyses do not fully support this hypothesis, indicating that there are carcinogenetic factors behind this noticeable increasing incidence. Although we have undoubtedly understood the biology and molecular pathways underlying thyroid carcinogenesis in a better way, we have made very little progresses in identifying a risk profile for DTC, and our knowledge of risk factors is very similar to what we knew 30-40 years ago. In addition to ionizing radiation exposure, the most documented and established risk factor for DTC, we also investigated the role of other factors, including eating habits, tobacco smoking, living in a volcanic area, xenobiotics, and viruses, which could be involved in thyroid carcinogenesis, thus, contributing to the increase in DTC incidence rates observed.

Obesity and thyroid cancer

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.

Thyroid cancer risk and smoking status: a meta-analysis

PURPOSE

Previous researchers have reported an inverse association between cigarette smoking and thyroid cancer risk. To summarize the role of smoking in relation to thyroid cancer occurrence, we conducted a meta-analysis.

METHODS

We performed a meta-analysis of 31 eligible studies to summarize the data describing the association between thyroid cancer occurrence and smoking. The case-control studies consisted of 6,260 thyroid cancer cases and 32,935 controls. Cohort studies contained 2,715 thyroid cancer patients that participated from recruitment to follow-up. Q-statistic and I (2) statistic were calculated to examine heterogeneity. Summary relative risks (RRs) and 95 % confidence intervals (95 % CIs) were calculated using a random effects model. Potential sources of heterogeneity were investigated via subgroup and sensitivity analyses, and publication biases were estimated.

RESULTS

Thyroid cancer risk was reduced in persons who had ever-smoked (RR = 0.79; 95 % CI 0.70-0.88) compared with never-smokers. However, strong evidence of heterogeneity was found among the investigated studies; therefore, subgroup analyses were conducted according to study type, smoking status, study location, source of controls, sex, and histological type of thyroid cancer. When the data were stratified by smoking status, an inverse association was observed only among current smokers (RR = 0.74; 95 % CI 0.64-0.86), not former smokers (RR = 1.01; 95 % CI 0.92-1.10). An inverse association was observed only in case-control studies (RR = 0.75; 95 % CI 0.66-0.85).

CONCLUSIONS

This meta-analysis of geographically diverse epidemiological data suggests that smoking, particularly current smoking, may influence susceptibility to thyroid cancer. Further well-designed studies with larger sample sizes should be conducted.

Obesity and the risk of papillary thyroid cancer: a pooled analysis of three case-control studies

BACKGROUND

There is a correlation between temporal trends of obesity prevalence and papillary thyroid cancer (PTC) incidence in the United States. Obesity is a well-recognized risk factor for many cancers, but there are few studies on the association between obesity and PTC risk. We investigated the association between anthropometric measurements and PTC risk using pooled individual data from three case-control populations.

METHODS

Height and weight information were obtained from three independent case-control studies, including 1917 patients with PTC (1360 women and 557 men) and 2127 cancer-free controls from the United States, Italy, and Germany. Body mass index (BMI), body fat percentage, and body surface area (BSA) were calculated. An unconditional logistic regression model was used to calculate odds ratios (ORs) and confidence intervals (CIs) with respect to risk of PTC, adjusted by age, sex, race/ethnicity, and study site.

RESULTS

In the pooled population, for both men and women, an increased risk of PTC was found to be associated with greater weight, BMI, body fat percentage, and BSA, whereas a reduced risk of PTC was associated with greater height, in the pooled population for both men and women. Compared with normal-weight subjects (BMI 18.5-24.9 kg/m2), the ORs for overweight (BMI 25-29.9 kg/m2) and obese (BMI≥30 kg/m2) subjects were 1.72 [CI 1.48-2.00] and 4.17 [CI 3.41-5.10] respectively. Compared with the lowest quartile of body fat percentage, the ORs for the highest quartile were 3.83 [CI 2.85-5.15] in women and 4.05 [CI 2.67-6.15] in men.

CONCLUSION

Anthropometric factors, especially BMI and body fat percentage, were significantly associated with increased risk of PTC. Future studies of anthropometric factors and PTC that incorporate intermediate factors, including adiposity and hormone biomarkers, are essential to help clarify potential mechanisms of the relationship.

The role of the inflammatory microenvironment in thyroid carcinogenesis

Immune responses against thyroid carcinomas have long been demonstrated and associations between inflammatory microenvironment and thyroid carcinomas repeatedly reported. This scenario has prompted scientists throughout the world to unveil how the inflammatory microenvironment is established in thyroid tumors and what is its influence on the outcome of patients with thyroid carcinoma. Many studies have reported the role of evasion from the immune system in tumor progression and reinforced the weakness of the innate immune response toward thyroid cancer spread in advanced stages. Translational studies have provided evidence that an increased density of tumor-associated macrophages in poorly differentiated thyroid carcinoma (DTC) is associated with an aggressive phenotype at diagnosis and decreased cancer-related survival, whereas well-DTC microenvironment enriched with macrophages is correlated with improved disease-free survival. It is possible that these different results are related to different microenvironments. Several studies have provided evidence that patients whose tumors are not infiltrated by lymphocytes present a high recurrence rate, suggesting that the presence of lymphocytes in the tumor microenvironment may favor the prognosis of patients with thyroid carcinoma. However, the effect of lymphocytes and other immune cells on patient outcome seems to result from complex interactions between the tumor and immune system, and the molecular pattern of cytokines and chemokines helps to explain the involvement of the immune system in thyroid tumor progression. The inflammatory microenvironment may help to characterize aggressive tumors and to identify patients who would benefit from a more invasive approach, probably sparing the vast majority of patients with an indolent disease from unnecessary procedures.

Is lower socioeconomic status associated with more advanced thyroid cancer stage at presentation? A study in two Canadian centers

BACKGROUND

Some studies have shown a higher incidence of thyroid cancer in patients with insurance coverage and higher socioeconomic status (SES), and a higher thyroid cancer stage in patients with lower SES, suggesting SES-related health disparity in thyroid cancer. However, it is not known if the same is evident under a universal healthcare system such as that in Canada.

METHODS

We used data from the Canadian Thyroid Cancer Consortium, a large thyroid cancer registry that collects data from two major thyroid cancer referral centers (London, Ontario, and Halifax, Nova Scotia). We included patients who presented with thyroid cancer between 1998 and 2011. We determined age at presentation, sex, and thyroid cancer status using the American Joint Committee on Cancer (AJCC) staging criteria. Individuals' postal codes were used to retrieve data from the Canadian census for the years 1996, 2001, and 2006 to approximate household income. Ordered logistic regression was used to determine odds ratios of presenting with more advanced stage thyroid cancer as they relate to income, age, and sex.

RESULTS

We included 1701 patients: 1334 cases from London and 367 from Halifax. Thyroid cancer was diagnosed more frequently in the higher SES groups (p<0.001). Compared to patients in the top income quintile, patients in the lowest and second-lowest income quintiles had significantly higher odds of having more advanced stage thyroid cancer at presentation (OR 1.58, p=0.002; 1.37, p=0.024 respectively).

CONCLUSIONS

Our study suggests that, similar to countries that lack a universal healthcare system, health disparity in thyroid cancer also exists in Canada. It appears that while thyroid cancers were diagnosed more frequently in Canadian patients of higher SES, Canadian patients in the lower SES groups had more advanced stage thyroid cancer at presentation.

Obesity and thyroid cancer: a clinical update

BACKGROUND

In the last decade, significant contributions have been made to our knowledge on the connection between the thyroid and adipose tissue. Modern society is faced with climbing rates of obesity and metabolic syndrome, and there is accumulating evidence of an association between obesity and increased cancer risk. The aim of this review is to summarize clinical data on the association between thyroid cancer (TC) and obesity and briefly to present plausible hypotheses explaining this interplay.

SUMMARY

We performed a search on the PubMed database for studies published in English from 1980 to March 2013 using the terms "thyroid cancer," "obesity," and "body mass index." Although there is inconsistency among the clinical studies, it seems that overweight and obesity are related to a modestly increased TC risk. Various factors, such as sex, ethnicity, and body changes during certain life periods, for example adolescence, may influence the association between obesity and TC risk. There are preliminary data linking obesity with a less favorable clinicopathologic profile of TC. However, validation with larger multicenter studies is needed. The precise underlying mechanisms have not yet been elucidated, but the insulin-IGF axis and adipokines, such as leptin and adiponectin, might be implicated in the link between excess weight and TC.

CONCLUSIONS

Given the rising prevalence of TC and the development of obesity as an epidemic, it is important to clarify its connection with TC as well as the mediating pathways. However, unless this association is confirmed and causation proven, screening for TC in overweight and obese subjects-a rapidly increasing body of the general population-does not seem justified.

Physical activity, diabetes, and risk of thyroid cancer: a systematic review and meta-analysis

Thyroid cancer incidence has been increasing more rapidly over time than the occurrence of cancers of other sites, and interest in potential adverse relations of diabetes and lack of physical activity to thyroid cancer risk is accumulating. We conducted a systematic review and meta-analysis of published epidemiologic studies on the relations of physical activity and diabetes to thyroid cancer according to the Meta-analysis of Observational Studies in Epidemiology guidelines. Published studies were identified through a search in MEDLINE and EMBASE. Random-effects models were used to summarize thyroid cancer risk estimates comparing high versus low levels of physical activity, and separately, comparing individuals with diabetes versus those without diabetes. Meta-regression analyses were performed to evaluate potential effect modification by study design and thyroid cancer risk factors. Information was extracted from seven studies of physical activity and thyroid cancer and from six studies of diabetes and thyroid cancer. The number of individuals from studies on physical activity was 939,305 (yielding 2,250 incident thyroid cancer cases) and from studies on diabetes it was 960,840 (yielding 1,230 cases). The summary relative risk (RR) estimate from cohort and case-control studies combined indicated no association between physical activity and thyroid cancer (summary RR 1.06, 95 % confidence interval (CI) 0.79-1.42). Subgroup-analyses revealed a significant positive association between physical activity and thyroid cancer in cohort studies (summary RR 1.28; 95 % CI 1.01-1.63), whereas the relation was suggestively inverse in case-control studies (summary RR 0.70; 95 % CI 0.48-1.03; p for heterogeneity = 0.005). Individuals with diabetes showed a borderline statistically significant increased risk of thyroid cancer compared with those without diabetes (summary RR 1.17; 95 % CI 0.99-1.39). The relations of physical activity and diabetes to thyroid cancer were not modified by sex, number of adjustment factors, and adjustments for adiposity, smoking, and study quality. In this comprehensive systematic review and meta-analysis, no significant association between physical activity and thyroid cancer was found. Diabetes showed a suggestive positive relation with risk of thyroid cancer.