Serum thyrotropin concentration as a biochemical predictor of thyroid malignancy in patients presenting with thyroid nodules

Rotating Night Shift Work, Sleep, and Thyroid Cancer Risk in the Nurses' Health Study 2

Night shift work has been associated with breast, prostate, and colorectal cancer, but evidence on other types of cancer is limited. We prospectively evaluated the association of rotating night shift work, sleep duration, and sleep difficulty with thyroid cancer risk in the Nurses' Health Study 2 (NHS2). We assessed rotating night shift work duration (years) at baseline and throughout follow-up (1989-2015) and sleep characteristics in 2001. Cox proportional hazard models, adjusted for potential confounders, were used to calculate hazard ratios (HR) and 95% confidence intervals (CI) for (a) shift work duration, (b) sleep duration, and (c) difficulty falling or staying asleep. We stratified the analyses of night shift work by sleep duration and sleep difficulty. Over 26 years of follow-up, 588 incident cases were identified among 114,534 women in the NHS2 cohort. We observed no association between night shift work and the risk of thyroid cancer. Difficulty falling or staying asleep was suggestively associated with a higher incidence of thyroid cancer when reported sometimes (HR 1.26, 95% CI 0.95, 1.66) and all or most of the time (HR 1.35, 95% CI 1.00, 1.81). Night shift workers (10+ years) with sleep difficulty all or most of the time (HR 1.47; 0.58-3.73) or with >7 h of sleep duration (HR 2.17; 95% CI, 1.21-3.92) had a higher risk of thyroid cancer. We found modest evidence for an increased risk of thyroid cancer in relation to sleep difficulty, which was more pronounced among night shift workers.

The association between thyroid-stimulating hormone and thyroid nodules, goiter and thyroid antibody positivity

Background

The relationship between normal thyroid-stimulating hormone (TSH) levels and thyroid disease in adults remains controversial. This study aimed to investigate the correlation between serum TSH levels, particularly those falling within the normal range, and thyroid diseases in Chinese adults, including thyroid nodules (TN), goiter (GR), and thyroid antibody positivity.

Materials and methods

This research was a cross-sectional study conducted in an adult population in Tianjin, China. Thyroid volume (Tvol) and TN were assessed using thyroid ultrasonography. Fasting venous blood and spot urine samples were collected to evaluate thyroid function and iodine status.

Results

A total of 2460 subjects participated in the survey. The prevalence of thyroid dysfunction was 9.76%, and abnormal TSH levels were found to potentially increase the risk of GR and thyroid antibody positivity in adults. A total of 2220 subjects with TSH within the normal reference range were included in the further study. In these patients, Tvol decreased as TSH levels increased, in both men and women (P < 0.0001). Low TSH levels (0.27-1.41 IU/mL) were identified as a risk factor for TN (odds ratio [OR], 1.46; 95% CI: 1.14-1.87) and GR (OR 5.90, 95% CI 2.27-15.3). Upon stratification by sex and age, the risk of TN was found to be higher in women and elderly individuals (≥60 years old), while the risk of GR was found to be higher in men and younger individuals (<60 years old). High TSH levels (2.55-4.2 IU/mL) were identified as a risk factor for thyroid antibody positivity (OR, 1.53; 95% CI: 1.11-2.10). Men and younger individuals with high TSH levels exhibited a higher risk of thyroid antibody positivity.

Conclusion

In adults with normal TSH levels, low TSH levels were associated with an increased risk of TN and GR, whereas high TSH levels were associated with thyroid antibody positivity. The research also suggests that adults whose TSH levels at upper or lower limits of the normal range should be reviewed regularly.

The associations between thyroid-related hormones and the risk of thyroid cancer: An overall and dose-response meta-analysis

Objective

Thyroid cancer (TC) is one of the most common malignant tumours of the endocrine system. Thyroid-stimulating hormone (TSH) is known as being a risk factor for TC, but other thyroid-related hormones are inconsistently associated with TC. The purpose of this study was to comprehensively evaluate the relationships between thyroid-related hormones and the risk of TC.

Methods

This study utilized searches of PubMed, Embase, Web of Science and Cochrane library up to the date of March 31st, 2022. Additionally, we performed a systematic review of related original studies combining overall and dose-response meta-analyses.

Results

A total of 30, 5 and 7 articles were included in the meta-analyses of TSH, Free triiodothyronine (FT3), free thyroxine (FT4) and TC risk with 58437, 6813 and 7118 participants respectively. An increased risk of TC was associated with high TSH exposure (OR=1.28, 95% CI: 1.19-1.37, P < 0.001) in the overall meta-analysis. For every 1 mU/L increase in TSH, the risk of TC increased by 16%. However, in those studies that used healthy subjects as controls, the association was not statistically significant(P=0.62). Additionally, high serum FT3 demonstrated a reduced risk of TC, with a combined OR of 0.86 in the fixed-effect model (95% CI: 0.81-0.90, P < 0.001). In addition, a statistically significant increase in TC risk was found when FT4 concentrations reached a certain threshold (approximately 2.2 ng/dL) in the dose-response meta-analysis.

Conclusions

Significant associations between thyroid-related hormones and the risk of TC were found in this study. Further research is needed to understand the underlying mechanisms.

Can Thyrotropin, Tri-Iodothyronine, and Thyroxine Hormones be Predictors of Cancer in Thyroid Lesions?

Background Thyroid nodules are a common medical problem worldwide. This study aims to investigate and elucidate the relationship between thyroid-stimulating hormone (TSH), thyroxine (T4), and triiodothyronine (T3), and malignant thyroid nodules. Methods This prospective cross-sectional study was conducted at a public specialist hospital in Saudi Arabia from February 2020 to February 2021. All thyroid nodules were scanned using ultrasound imaging, and the largest diameter was measured for each and classified according to the American College of Radiology (ACR) Thyroid Imaging Reporting and Data System (TIRADS) classification system. Thyroid function tests TSH, T3, and T4 were measured. Definitive diagnoses of thyroid nodules were given based on cytology. A one-way analysis of variance (ANOVA) test was used to compare means, and cross-tabulation was used to correlate the variables in the study. Results A total of 222 patients participated in this study; 23.42% were male and 76.57% were females. The mean age was 44.73 ± 13.31 years (range: 18 to 85 years). The percentage of malignancy was 20.6%, 36.3%, and 91.2% in TIRADS 3, TIRADS 4, and TIRADS 5, respectively. A weak positive linear relationship was noted between nodule size and TSH (R²= 0.012). The study demonstrates that TSH increases in malignant nodules more than in benign nodules, while T4 and T3 are decreased in malignant nodules. Conclusion The level of TSH increases in patients with malignant thyroid nodules more than in benign nodules, which can be used as a predictor of malignancy, while T4 and T3 reduced in malignant nodules with an ambiguous relationship.

The association between serum concentration of thyroid hormones and thyroid cancer: a cohort study

The impact of serum thyroid hormone levels on thyroid cancer risk is unclear. Some studies reported that elevated thyroid-stimulating hormone (TSH) is associated with higher risk for incidence of thyroid cancer, but other studies reported no relationship. We conducted a large cohort study in 164,596 South Korean men and women who were free of thyroid cancer at baseline and underwent health examination with hormone levels of thyroid function. A parametric proportional hazard model was used to evaluate the adjusted hazard ratio (HR) and 95% CI. During 2,277,749.78 person-years of follow-up, 1280 incident thyroid cancers were identified (men = 593, women = 687). Among men, the multivariable-adjusted HR (95% CI) for thyroid cancer comparing low levels of TSH with normal levels of TSH was 2.95 (1.67-5.23), whereas the corresponding HR (95% CI) in women was 1.5 (0.88-2.55). High levels of free T4 and free T3 were also associated with incident thyroid cancer in both men and women. In clinical implication, overt hyperthyroidism is associated with thyroid cancer in both men and women. Within the euthyroid range, the highest tertile of TSH was associated with a lower risk of thyroid cancer than the lowest TSH tertile and the highest FT4 tertile was associated with a higher risk of thyroid cancer than the lowest FT4 tertile in both men and women. Our finding indicates that low levels of TSH and high levels of FT4, even within the normal range, were associated with an increased risk of incident thyroid cancer.

Sleep quality of patients with papillary thyroid carcinoma: a prospective longitudinal study with 5-year follow-up

We evaluated the pre- and postoperative sleep quality of patients with newly diagnosed papillary thyroid carcinoma (PTC) who underwent thyroid surgery, and investigated the factors associated with persistent poor sleep quality. The Pittsburgh sleep quality index (PSQI), Epworth sleepiness scale, and Stanford sleepiness scale were used to estimate sleep quality and daytime sleepiness. Face-to-face surveys were conducted preoperatively, and 1, 4, and 10 months after thyroid surgery. The PSQI was administered during a telephone interview about after 5 years after surgery. Forty-six patients (mean age 47.3 ± 10.1 years) with PTC (11 males, 35 females) were included in this study. Twenty-one participants underwent lobectomy and 25 underwent total thyroidectomy. Preoperatively, 35 (76.1%) patients showed poor sleep quality. PSQI scores at postoperative 1, 4, and 10 months were significantly lower than preoperative scores (p < 0.001). Postoperative 5-year PSQI scores decreased significantly compared to the preoperative scores (p < 0.001). Patients newly diagnosed with PTC suffered from sleep disturbance before and after surgery for at least 10 months, recovering to a comparable rate of sleep disturbance with the general population by 5 years after surgery. Higher preoperative PSQI score was at risk for prolonged poor sleep quality in patients with PTC.

Prospects of Testing Diurnal Profiles of Expressions of TSH-R and Circadian Clock Genes in Thyrocytes for Identification of Preoperative Biomarkers for Thyroid Carcinoma

Thyroid Nodules (TN) are frequent but mostly benign, and postoperative rate of benign TN attains the values from 70% to 90%. Therefore, there is an urgent need for identification of reliable preoperative diagnosis markers for patients with indeterminate thyroid cytology. In this study, an earlier unexplored design of research on preoperative biomarkers for thyroid malignancies was proposed. Evaluation of reported results of studies addressing the links of thyroid cancer to the circadian clockwork dysfunctions and abnormal activities of Thyroid-Stimulating Hormone (TSH) and its receptor (TSH-R) suggested diagnostic significance of such links. However, there is still a gap in studies of interrelationships between diurnal profiles of expression of circadian clock genes and TSH-R in indeterminate thyroid tissue exposed to different concentrations of TSH. These interrelationships might be investigated in future in vitro experiments on benign and malignant thyrocytes cultivated under normal and challenged TSH levels. Their design requires simultaneous measurement of diurnal profiles of expression of both circadian clock genes and TSH-R. Experimental results might help to bridge previous studies of preoperative biomarkers for thyroid carcinoma exploring diagnostic value of diurnal profiles of serum TSH levels, expression of TSH-R, and expression of circadian clock genes.

Serum TSH Level as a Simple Efficient Tool to Assess the Risk of Thyroid Malignancy in Euthyroid Patients with Indeterminate Cytology - A Cohort Study

Context

A significant number of fine-needle aspiration cytology (FNAC) for thyroid nodules is reported as indeterminate. Expensive molecular testing can give a clue to the possibility of malignancy in this group. The effectiveness of serum thyroid-stimulating hormone (TSH) levels as a diagnostic tool in euthyroid patients with indeterminate cytology has not been previously studied, especially in the Indian population.

Aims

This study was conducted to evaluate the predictive efficacy of serum TSH in the early diagnosis and treatment of malignancy.

Settings and Design

This is a retrospective cross-sectional study on a cohort of patients who presented to our department with complaints of thyroid swelling and underwent thyroidectomy.

Methods and Material

Euthyroid patients who underwent thyroid surgery for newly diagnosed thyroid nodules with FNAC reported as indeterminate cytology were included in our study. Based on the histopathological report, the patients were divided into two groups and into quartiles based on TSH values.

Statistical Analysis Used

The mean difference in the numerical variables between groups was compared using the independent two-sample 't' test for parametric data and Mann-Whitney 'u' test for non-parametric data. A logistic regression analysis was done with age, sex, TSH level and nodule size as dependant variables and malignancy as the independent variable.

Results

There were 211 patients in group A and 93 in group B. Patients with malignancy confirmed on final histopathology showed higher serum TSH levels compared to benign nodules (2.93 ± 1.067 vs 1.73 ± 1.051, P = <0.001). The mean TSH levels of all types of malignant nodules correlated with our test model (>2.185 mIU/L).

Conclusions

Serum TSH above 2.185 mIU/mL is a good predictor of malignancy in indeterminate nodules. It is an inexpensive, safe and reliable diagnostic screening test for the risk of malignancy in an indeterminate nodule.

OPG is associated with thyroid nodule development in type 2 diabetes

Background

Thyroid nodule prevalence is increasing lately, especially in diabetes, but the mechanism of which is not clear. In this study, we investigated if osteoprotegerin (OPG) is involved in the pathogenesis of thyroid nodules in diabetes.

Methods

A total of 7568 individuals with detailed information and ultrasound examination results were studied for the prevalence of thyroid nodules. Among them, 1883 were with type 2 diabetes and 5685 were non‐diabetic. Then, 1120 individuals were randomly selected for the measurement of OPG. Diabetic rats were made by feeding a high‐fat‐high‐fructose diet for 28 weeks. Rats fed with a normal diet were as controls. Fresh thyroid tissues were obtained and fixed, dehydrated, and embedded in paraffin for hematoxylin‐eosin staining and observing pathological changes. qPCR and western blot were used to detect OPG expression in rat thyroid tissues.

Results

We found that HbA1c is an independent risk factor for thyroid nodules (Exp [β] = 1.158, p < 0.001). The prevalence of thyroid nodules in type 2 diabetes was higher than that in non‐diabetes (53.9% vs. 46.7%, p < 0.001). Serum OPG levels were significantly elevated in the diabetes group than in the non‐diabetes group (3160.17 pg/ml vs. 2819.39 pg/ml, p < 0.01). The expression of OPG increased significantly in the thyroid tissues of diabetic rats.

Conclusion

Osteoprotegerin may be associated with thyroid nodule development in diabetes.

Serum TSH as a predictor of malignancy in indeterminate thyroid nodules

INTRODUCTION

Thyroid nodules are lesions that are radiologically distinct from the thyroid parenchyma. Cervical ultrasound diagnoses 19-67% of nodules and is crucial in identifying those that lack cytological characterisation. Approximately 25% of biopsies reveal an indeterminate cytological result (Bethesda III), in which the risk of malignancy is variable (5-15%). The clinical importance of the diagnostic strategy used for thyroid nodules results from the need to exclude malignancy. The aim of this study was to evaluate the usefulness of serum thyroid-stimulating hormone (TSH) levels as a predictor of malignancy in cytologically indeterminate thyroid nodules.

METHODS

Our retrospective study included 40 patients with cytologically indeterminate thyroid nodules seen in our hospital between January 2013 and December 2017. Clinical parameters were reviewed, including age, gender, serum TSH levels, family history of thyroid carcinoma, radiation exposure and some sonographic features of the nodules. Statistical analysis was performed using SPSS. Statistical significance was defined as p<0.05.

RESULTS

Female gender was predominant (85%) and the mean (SD) age was 53.3 (15) years. Thyroid carcinoma was confirmed in 28% of patients. Median TSH levels were higher in patients with malignant (2.73µIU/ml) compared with benign (1.56µIU/ml) nodules (p<0.05). We demonstrated an increased risk of malignancy in patients with TSH levels of 2.68µIU/ml or above (p<0.05).

CONCLUSION

Higher serum TSH levels are associated with an increased risk of thyroid carcinoma in cytologically indeterminate nodules. TSH can become a fundamental diagnostic tool in stratifying the risk of malignancy and assist in diagnostic and therapeutic approaches to these nodules.

Pattern analysis for prognosis of differentiated thyroid cancer according to preoperative serum thyrotropin levels

Serum thyrotropin (TSH) level after thyroid surgery affects the prognosis of differentiated thyroid cancer (DTC). However, the effects of preoperative serum TSH levels on the prognosis of DTC remain contradictory. In this study, to better understand the relationship between preoperative TSH levels and the prognosis of DTC, we performed pattern analysis of prognostic factors of DTC according to preoperative serum TSH levels. We retrospectively reviewed the clinical records of patients who were diagnosed and treated for DTC at the Samsung Medical Center, between 1994 and 2016. We reviewed preoperative serum TSH levels and performed a pattern analysis with prognostic risk factors for DTC. For pattern analysis, TSH was divided into 10 groups of equal fractions (TSH decile). We found a linear association between preoperative TSH levels and extra-thyroidal extension and lymph node metastasis. However, primary tumor size and initial distant metastasis showed a bimodal peak, which was similar to the pattern of overall and disease-specific death. We found that preoperative TSH range which showed the lowest mortality rate was about 0.8 to 1.59 mIU/L, which are slightly lower normal TSH levels. Although there was no linear trend, the primary tumor size, initial distant metastasis, and mortality of DTC were closely related with preoperative TSH decile and they showed a bimodal pattern. The results obtained in this study provide additional information for understanding the association between preoperative TSH levels and DTC prognosis.

Prognosis of papillary thyroid carcinoma in relation to preoperative subclinical hypothyroidism

INTRODUCTION

It has been established that thyroid-stimulating hormone (TSH) stimulates the growth and development of thyroid malignancy, and a higher serum TSH level is associated with the incidence of thyroid cancer and an advanced tumour stage. This study aimed to evaluate the association of preoperative subclinical hypothyroidism with the prognosis of papillary thyroid cancer (PTC).

METHODS

A total of 466 patients who underwent surgery for PTC between December 2006 and June 2009 were enrolled. Among them, 44 patients had subclinical hypothyroidism, while 422 did not have subclinical hypothyroidism, as diagnosed using the preoperative thyroid function test. We compared the recurrence rate and association with clinicopathological features in the two groups.

RESULTS

The median patient age was 46.9 years (17-74 years). There were 420 female and 46 male patients. The median follow-up duration was 81.4 months. There were no statistical differences between the two groups with respect to age, sex, tumour size, extrathyroidal extension, multifocality, lymph node metastasis, TNM stages, recurrence and disease-free survival, despite a significant difference in the average TSH concentrations of the two groups.

CONCLUSIONS

Our results suggest that preoperative subclinical hypothyroidism was not associated with tumour aggressiveness and recurrence in PTC.

The Cancer Risk among Physicians in Taiwan, a Population-Based Propensity Score Matched Cohort Study

Background

The field of physician health is gaining increasing attention; however, most research and interventions have concentrated on factors such as job stress, mental health, and substance abuse. The risks of major cancers in physicians remain unclear. We used a propensity score-matched analysis to investigate the risk of cancer in physicians relative to the general population who had no healthcare-related professional background.

Methods

Data were obtained from the National Health Insurance system in Taiwan. The physician cohort contained 29,713 physicians, and each physician was propensity score-matched with a person from the general population.

Results

The physicians demonstrated a 0.90-fold lower risk of all-cancers (95% confidence interval [CI] = 0.83 - 0.96) when compared with the general population. Female physicians had a higher risk of cancer than male physicians (adjusted hazard ratio [HR] = 1.59; 95% CI = 1.28 - 1.96). Physicians had higher risks of prostate (HR = 1.26; 95% CI = 1.00 - 1.59) and thyroid cancers (HR = 3.16; 95% CI = 1.69 - 5.90) when compared with the general population.

Conclusion

Physicians have lower rates of overall cancer risk than the general population. Female physicians have higher cancer risks than male physicians. Male physicians have higher risks of thyroid and prostate cancer relative to the general population.

Thyroid Cancer and Circadian Clock Disruption

Thyroid cancer (TC) represents the most common malignancy of the endocrine system, with an increased incidence across continents attributable to both improvement of diagnostic procedures and environmental factors. Among the modifiable risk factors, insulin resistance might influence the development of TC. A relationship between circadian clock machinery disfunction and TC has recently been proposed. The circadian clock machinery comprises a set of rhythmically expressed genes responsible for circadian rhythms. Perturbation of this system contributes to the development of pathological states such as cancer. Several clock genes have been found deregulated upon thyroid nodule malignant transformation. The molecular mechanisms linking circadian clock disruption and TC are still unknown but could include insulin resistance. Circadian misalignment occurring during shift work, jet lag, high fat food intake, is associated with increased insulin resistance. This metabolic alteration, in turn, is associated with a well-known risk factor for TC i.e., hyperthyrotropinemia, which could also be induced by sleep disturbances. In this review, we describe the mechanisms controlling the circadian clock function and its involvement in the cell cycle, stemness and cancer. Moreover, we discuss the evidence supporting the link between circadian clockwork disruption and TC development/progression, highlighting its potential implications for TC prevention, diagnosis and therapy.

GWAS of thyroid stimulating hormone highlights pleiotropic effects and inverse association with thyroid cancer

Thyroid stimulating hormone (TSH) is critical for normal development and metabolism. To better understand the genetic contribution to TSH levels, we conduct a GWAS meta-analysis at 22.4 million genetic markers in up to 119,715 individuals and identify 74 genome-wide significant loci for TSH, of which 28 are previously unreported. Functional experiments show that the thyroglobulin protein-altering variants P118L and G67S impact thyroglobulin secretion. Phenome-wide association analysis in the UK Biobank demonstrates the pleiotropic effects of TSH-associated variants and a polygenic score for higher TSH levels is associated with a reduced risk of thyroid cancer in the UK Biobank and three other independent studies. Two-sample Mendelian randomization using TSH index variants as instrumental variables suggests a protective effect of higher TSH levels (indicating lower thyroid function) on risk of thyroid cancer and goiter. Our findings highlight the pleiotropic effects of TSH-associated variants on thyroid function and growth of malignant and benign thyroid tumors.

Could Serum TSH Levels Predict Malignancy in Euthyroid Patients Affected by Thyroid Nodules with Indeterminate Cytology?

BACKGROUND

Serum TSH levels in the upper-normal range were reported to be associated with increased risk of thyroid malignancy. However, measurement of TSH levels is currently not recommended for assessing the risk of malignancy in patients with newly diagnosed thyroid nodules.

OBJECTIVE

To evaluate a possible relationship between the serum levels of TSH and the histological outcome of patients undergoing thyroidectomy for thyroid nodules with indeterminate cytology.

MATERIALS AND METHODS

We collected the clinical data of all patients who had performed ultrasound-guided FNA of thyroid nodules with cytological diagnosis of indeterminate lesions (TIR3A and TIR3B) and serum TSH levels within the normal range. All patients had been submitted to thyroid surgery (hemi or thyroidectomy, as appropriate), and histological diagnosis had been performed.

RESULTS

A histological diagnosis of thyroid malignancy was rendered in 74/378 (19.6%) nodules. Patients with histologically proven thyroid malignancy were characterized by higher serum levels of TSH as compared to patients with histologically proven benign nodules (3.03 ± 1.16 vs. 2.37 ± 1.19 mIU/L, p < 0.001). To further analyze the role of serum TSH in predicting thyroid cancer, patients were stratified in 4 groups according to quartiles of TSH concentrations. The prevalence of malignancy was 12.2% for the first quartile and 50.0% for the last quartile. ROC curve analysis identified that a serum TSH level of ≥2.7 mIU/L predicted thyroid malignancy with a sensitivity of 61% and a specificity of 65%.

CONCLUSIONS

TSH levels in the upper-normal range are associated with an increased risk of thyroid malignancy in patients affected by thyroid nodules with indeterminate cytology at FNA. The measurement of serum TSH levels represents an easily performed additional tool for decision-making in patients with indeterminate cytological findings.

The Difference in Thyroid Stimulating Hormone Levels between Differentiated Carcinoma and Benign Enlargement

Introduction  Papillary and follicular thyroid carcinoma are common head and neck cancers. This cancer expresses a thyroid stimulating hormone (TSH) receptor that plays a role as a cancer stimulant substance. This hormone has a diagnostic value in the management of thyroid carcinoma. Objective  The present study aimed to determine the difference in TSH levels between differentiated thyroid carcinoma and benign thyroid enlargement. Methods  The present research design was a case-control study. The subjects were patients with thyroid enlargement who underwent thyroidectomies at the Dr. Sardjito General Hospital, Yogyakarta, Indonesia. Thyroid stimulating hormone levels were measured before the thyroidectomies. The inclusion criteria for the case group were: 1) differentiated thyroid carcinoma, and 2) complete data; while the inclusion criteria for the control group were: 1) benign thyroid enlargement, and 2) complete data. The exclusion criteria for both groups were: 1) patients suffering from thyroid hormone disorders requiring therapy before thyroidectomy surgery, 2) patients receiving thyroid suppression therapy before the thyroidectomy was performed, and 3) patients suffering from severe chronic diseases such as renal insufficiency, and severe liver disease. Results  There were 40 post-thyroidectomy case group patients and 40 post-thyroidectomy control group patients. There were statistically significant differences in TSH levels between the groups with differentiated thyroid carcinoma and benign thyroid enlargement ( p  = 0.001; odds ratio [OR] = 8.42; 95% confidence interval [CI]: 3.19-36.50). Conclusion  Based on these results, it can be concluded that there were significant differences in TSH levels between the groups with differentiated thyroid carcinoma and benign thyroid enlargement.

Interconnection between circadian clocks and thyroid function

Circadian rhythmicity is an approximately 24-h cell-autonomous period driven by transcription-translation feedback loops of specific genes, which are referred to as 'circadian clock genes'. In mammals, the central circadian pacemaker, which is located in the hypothalamic suprachiasmatic nucleus, controls peripheral circadian clocks. The circadian system regulates virtually all physiological processes, which are further modulated by changes in the external environment, such as light exposure and the timing of food intake. Chronic circadian disruption caused by shift work, travel across time zones or irregular sleep-wake cycles has long-term consequences for our health and is an important lifestyle factor that contributes to the risk of obesity, type 2 diabetes mellitus and cancer. Although the hypothalamic-pituitary-thyroid axis is under the control of the circadian clock via the suprachiasmatic nucleus pacemaker, daily TSH secretion profiles are disrupted in some patients with hypothyroidism and hyperthyroidism. Disruption of circadian rhythms has been recognized as a perturbation of the endocrine system and of cell cycle progression. Expression profiles of circadian clock genes are abnormal in well-differentiated thyroid cancer but not in the benign nodules or a healthy thyroid. Therefore, the characterization of the thyroid clock machinery might improve the preoperative diagnosis of thyroid cancer.

The Relationship of Clinicopathological Factors of the Tumor with Preoperative TSH Level in Papillary Thyroid Cancers

Objective

Thyroid-stimulating hormone/thyrotropin (TSH) is known to induce malignancies and tissue growth of the thyroid gland. While the relationship of higher levels of TSH with advanced stages of cancer had been published in previous studies, the relationship of the tumor with the clinicopathological factors had not been completely evaluated. The aim of the present study was to evaluate the relationship between highly risky clinicopathological factors with preoperative high levels of TSH.

Materials and Methods

The records of 89 patients (67 females and 22 males) who underwent surgery for differentiated thyroid cancer between 2011 and 2013 were reviewed. The relationship of preoperative TSH between tumor size, multicentricity, lymphovascular invasion, extrathyroidal extension, central neck metastasis, and lateral neck metastasis was evaluated.

Results

The preoperative TSH levels were high in patients with multicentricity (p=0.022), lymphovascular invasion (p=0.018), and central neck metastasis (p=0.002). The prevalence of extrathyroidal extension (p=0.41), lymphovascular invasion (p=0.020), and central metastasis (p=0.009) was significantly high in patients with a TSH level ≥2.5 mIU/L. The preoperative TSH levels were determined as an independent predictive risk factor for central neck metastases (p=0.012) and extrathyroidal extension (p=0.041) in multinomial logistical regression analysis.

Conclusion

The power of radiological imaging for the identification of central neck metastases in preoperative evaluation is limited. The preoperative high level of TSH is an independent predictive factor for central metastases and extrathyroidal extension. It can help to predict tumor staging. Furthermore, related with multicentricity and lymphovascular invasion, it can affect the high risk characteristics of the tumor except the stage. The preoperative TSH level can be considered for the probability of preoperative metastases and can contribute to plan the extent of surgery.

Human relevance of follicular thyroid tumors in rodents caused by non-genotoxic substances

Chronic stimulation of the thyroid gland of rodents by TSH leads to thyroid follicular hyperplasia and subsequently to thyroid follicular adenomas and carcinomas. However, the interpretations of rodent thyroid tumors are contradictory. The U.S. Food and Drug Administration (FDA) concluded that findings with drugs that lead to increased levels of thyroid-stimulating hormone (TSH) in rats are not relevant to humans, whereas the U.S. Environmental Protection Agency (US EPA) concluded that chemicals that produce rodent thyroid tumors may pose a carcinogenic hazard for humans although the thyroid of rodents appears to be more sensitive to a carcinogenic stimulus than that of humans. Meanwhile, based on the CLP Criteria of the European Chemicals Agency (ECHA), rodent thyroid tumors caused by the induction of uridine-diphosphate-glucuronosyl transferases (UDGT) were assessed as not relevant to humans. To clarify these discrepant positions, the function and regulation of the thyroid gland are described and the types of thyroid tumors and the causes of their development in humans and animals are examined. Based on these data and the evidence that so far, except radiation, no chemical is known to increase the incidence of thyroid tumors in humans, it is concluded that rodent thyroid tumors resulting from continuous stimulation of the thyroid gland by increased TSH levels are not relevant to humans. Consequently, compounds that induce such tumors do not warrant classification as carcinogenic.

A predictive model of thyroid malignancy using clinical, biochemical and sonographic parameters for patients in a multi-center setting

BACKGROUND

Thyroid nodules are highly prevalent, but a robust, feasible method for malignancy differentiation has not yet been well documented. This study aimed to establish a practical model for thyroid nodule discrimination.

METHODS

Records for 2984 patients who underwent thyroidectomy were analyzed. Clinical, laboratory, and US variables were assessed retrospectively. Multivariate logistic regression analysis was performed and a mathematical model was established for malignancy prediction.

RESULTS

The results showed that the malignant group was younger and had smaller nodules than the benign group (43.5 ± 11.6 vs. 48.5 ± 11.5 y, p < 0.001; 1.96 ± 1.16 vs. 2.75 ± 1.70 cm, p < 0.001, respectively). The serum thyrotropin (TSH) level (median = 1.63 mIU/L, IQR (0.89-2.66) vs. 1.19 (0.59-2.10), p < 0.001) was higher in the malignant group than in the benign group. Patients with malignancies tested positive for anti-thyroglobulin antibody (TGAb) and anti-thyroid peroxidase antibody (TPOAb) more frequently than those with benign nodules (TGAb, 30.3% vs. 15.0%, p < 0.001; TPOAb, 25.6% vs. 18.0%, p = 0.028). The prevalence of ultrasound (US) features (irregular shape, ill-defined margin, solid structure, hypoechogenicity, microcalcifications, macrocalcifications and central intranodular flow) was significantly higher in the malignant group. Multivariate logistic regression analysis confirmed that age (OR = 0.963, 95% CI = 0.934-0.993, p = 0.017), TGAb (OR = 4.435, 95% CI = 1.902-10.345, p = 0.001), hypoechogenicity (OR = 2.830, 95% CI = 1.113-7.195, p = 0.029), microcalcifications (OR = 4.624, 95% CI = 2.008-10.646, p < 0.001), and central intranodular flow (OR = 2.155, 95% CI = 1.011-4.594, p < 0.05) were independent predictors of thyroid malignancy. A predictive model including four variables (age, TGAb, hypoechogenicity and microcalcification) showed an optimal discriminatory accuracy (area under the curve, AUC) of 0.808 (95% CI = 0.761-0.855). The best cut-off value for prediction was 0.52, achieving sensitivity and specificity of 84.6% and 76.3%, respectively.

CONCLUSION

A predictive model of malignancy that combines clinical, laboratory and sonographic characteristics would aid clinicians in avoiding unnecessary procedures and making better clinical decisions.

High Serum Thyrotropin Concentrations within the Reference Range: A Predictor of Malignancy in Nodular Thyroid Disease

OBJECTIVE

This study assessed whether or not a simple biochemical parameter, serum thyrotropin (TSH), within the reference range can predict the likelihood of thyroid malignancy in subjects undergoing fine-needle aspiration biopsy (FNAB) for thyroid nodules.

SUBJECTS AND METHODS

This cross-sectional study evaluated 236 patients without overt thyroid dysfunction who were not on levothyroxine therapy. They underwent FNAB of the thyroid nodules at the Clementino Fraga Filho University Hospital between 2011 and 2012. The reference range and serum TSH quartiles were determined according to age-specific values for serum TSH and then compared between the cases with benign thyroid nodular disease and differentiated thyroid carcinoma (DTC) based on surgical pathology reports.

RESULTS

Of the 236 patients, 201 (85.1%) underwent a surgical procedure (thyroidectomy) and 89/236 (44.3%) had DTC. The mean TSH concentrations were 2.09 ± 1.15 mU/L in benign patients versus 2.73 ± 1.33 mU/L in cases of DTC (p < 0.01). As TSH increased from quartiles 1 to 4, the frequency of a malignant diagnosis also increased progressively from 22% in quartile 1 to 65% in the last quartile (p ≤ 0.001).

CONCLUSION

Thyrotropin levels were positively associated with the diagnosis of DTC in thyroid nodules.

An overall and dose-response meta-analysis for thyrotropin and thyroid cancer risk by histological type

Thyrotropin (TSH) is thought as a risk factor for thyroid cancer. However, the effect of serum TSH might depend on histological types of thyroid cancer. We searched for related studies including serum TSH as an exposure and thyroid cancer as a result in PUBMED, EMBASE and Chinese National Knowledge Infrastructure up to April 21, 2016. This meta-analysis included 22 articles with 53,538 participants. When comparing all histological thyroid cancer, the pooled odds ratios of thyroid cancer in patients with nodules was found to increase significantly with higher serum TSH concentrations for differentiated thyroid carcinoma (1.88 vs .1.48, P = 0.0000) and papillary thyroid carcinoma (2.08 vs. 1.48, P = 0.0006). Each 1 mU/L increase of serum TSH was associated with 14% greater risk of thyroid cancer for all histological thyroid cancer, 16% for differentiated thyroid carcinoma and 22% for papillary thyroid carcinoma. In addition, high serum TSH was associated with a reduced risk for follicular thyroid carcinoma (OR = 0.73, 95% CI: 0.52, 1.02). This meta-analysis suggested high serum TSH concentration is risky for papillary thyroid carcinoma but not for follicular thyroid carcinoma.

BRAF-Oncogene-Induced Senescence and the Role of Thyroid-Stimulating Hormone Signaling in the Progression of Papillary Thyroid Carcinoma

Oncogene-induced senescence (OIS) explains the phenomenon of cellular senescence triggered by the action of oncogenes. It is a mechanism adopted by a cell to inhibit progression of benign tumors into malignancy, occurs in premalignant lesions, and is almost never present in malignant lesions. BRAF mutations occur in about 40-45% of all papillary thyroid carcinomas (PTCs) and of which 99.7% is the BRAFV600E mutation. A unique phenotype of the BRAFV600E mutation is the upregulation of the thyroid-stimulating hormone receptor (TSHR) on thyrocyte membranes. Despite the overexpression of the receptor, BRAFV600E cells undergo cell cycle arrest leading to OIS via a negative feedback signaling mechanism. A simultaneous increase in serum thyroid-stimulating hormone (TSH) in response to hypothyroidism (common in autoimmune diseases such as Hashimoto's thyroiditis) would cause senescent tumor cells to overcome OIS and proceed towards malignancy, hence showing the importance of TSH/TSHR signaling in the development of PTCs. Increase in TSH/TSHR signaling triggers an increase in levels of downstream enzymes such as manganese superoxide dismutase (MnSOD) and dual-specific phosphatase 6 (DUSP6) which eventually results in the production of oncogenic proteins such as c-Myc. Therefore, the detection of these genetic alterations as effective biomarkers for premalignant lesions of PTC is important in clinical settings and techniques such as polymerase chain reaction-mediated restriction fragment length polymorphism (PCR-RFLP) and real-time PCR can be used to detect the BRAFV600E point mutation and overexpression of TSHR, MnSOD, and DUSP6, respectively.

Role of thyroid hormones in the neoplastic process: an overview

Thyroid hormones (TH) are critical regulators of several physiological processes, which include development, differentiation and growth in virtually all tissues. In past decades, several studies have shown that changes in TH levels caused by thyroid dysfunction, disruption of deiodinases and/or thyroid hormone receptor (TR) expression in tumor cells, influence cell proliferation, differentiation, survival and invasion in a variety of neoplasms in a cell type-specific manner. The function of THs and TRs in neoplastic cell proliferation involves complex mechanisms that seem to be cell specific, exerting effects via genomic and nongenomic pathways, repressing or stimulating transcription factors, influencing angiogenesis and promoting invasiveness. Taken together, these observations indicate an important role of TH status in the pathogenesis and/or development of human neoplasia. Here, we aim to present an updated and comprehensive picture of the accumulated knowledge and the current understanding of the potential role of TH status on the different hallmarks of the neoplastic process.

Circulating thyroid cancer biomarkers: Current limitations and future prospects

Differentiated thyroid cancer (DTC) is the most common malignancy of the endocrine system. There has been a significant increase in its incidence over the past two decades attributable mainly to the use of more sensitive diagnostic modalities. Ultrasound-guided fine needle aspiration cytology is the mainstay of diagnosis of benign disorders and malignancy. However, approximately 20% of lesions cannot be adequately categorized as benign or malignant. In the postoperative setting, monitoring of thyroglobulin (Tg) levels has been employed for the detection of disease recurrence. Unfortunately, Tg antibodies are common and interfere with Tg measurement in this subset of patients. Despite this limitation, Tg remains the sole widely used thyroid cancer biomarker in the clinical setting. In an attempt to bypass antibody interference, research has focused mainly on mRNA targets thought to be exclusively expressed in thyroid cells. Tg and thyroid stimulating hormone receptor (TSHR) mRNA have been extensively studied both for discerning between benign disease and malignancy and in postoperative disease surveillance. However, results among reports have been inconsistent probably reflecting considerable differences in methodology. Recently, microRNA (miRNA) targets are being investigated as potential biomarkers in DTC. MiRNAs are more stable molecules and theoretically are not as vulnerable as mRNA during manipulation. Initial results have been encouraging but large-scale studies are warranted to verify and elucidate their potential application in diagnosis and postoperative surveillance of thyroid cancer. Several other novel targets, primarily mutations and circulating cells, are currently emerging as promising thyroid cancer circulating biomarkers. Although interesting and intriguing, data are limited and derive from small-scale studies in specific patient cohorts. Further research findings demonstrating their value are awaited with anticipation.

Association between Hashimoto's Thyroiditis and Thyroid Cancer in 64,628 Patients

Background

The incidence of thyroid cancer (TC) is increasing although explanatory causes are lacking. A link between cancer and inflammation is well documented but unclear for autoimmune thyroid diseases and TC. We aimed to systematically review the association between Hashimoto’s thyroiditis (HT) and papillary, follicular, medullary, anaplastic thyroid carcinoma, and thyroid lymphoma (TL).

Methods

PubMed, OVID Medline, Google Scholar, and the Cochrane Library were searched from 1955 to 2016. The inclusion criteria were age >18 years, ≥20 cases of HT or TC. We collectively examined the incidence of HT in TC and of TC in HT.

Results

We identified 36 studies (64,628 subjects) published between 1955 and 2016 from 13 countries. We found a relative risk (RR) of HT among papillary thyroid cancer (PTC) of 2.36 [95% confidence intervals (CIs) 1.55–3.29, p < 0.001], an RR of PTC among HT of 1.40 (95% CI 1.07–1.85, p = 0.016), and an RR of TL among HT of 9.74 (95% CI 3.93–24.13, p < 0.001).

Conclusion

We report an association between HT and PTC and between HT and TL. No association was found between HT and follicular, medullary, or anaplastic thyroid cancer.

The T4/T3 quotient as a risk factor for differentiated thyroid cancer: a case control study

Background

The incidence of thyroid nodules is increasing among patients in North America. Few of these nodules harbour malignancy, thus further research is required to identify predictive markers of malignant thyroid disease. This study set out to understand the relationship between the levels of fT4 and fT3 and differentiated thyroid cancer.

Methods

A case-control study was conducted with 142 cases and 86 controls from the McGill University Teaching Hospitals. All patients underwent thyroid surgery. Cases were defined as patients with malignant nodules confirmed on final pathology and controls were defined as patients with benign nodules. The serological levels of TSH, fT4 and fT3 were measured preoperatively. Odds ratios were determined for each parameter and logistic regressions were calculated between markers and probability of malignancy. Additionally, fT4 values were divided by fT3 values (fT4/fT3 quotient) for each patient and an odds ratio was calculated.

Results

Amongst cases, the mean TSH was 2.25 ± 0.360U/mL, fT4 was 14.8 ± 0.689pmol/L, and fT3 was 4.65 ± 0.463pmol/L. Amongst controls, the mean TSH was 2.36 ± 1.68U/mL, fT4 was 14.3 ± 1.71pmol/L, and fT3 was 5.27 ± 0.957pmol/L. Patients in the control group were more likely to have low TSH, while patients in the case group would have high fT4 and patients in the control group were more likely to have a low fT4. The OR for patients with TSH >4.4U/mL was 2.13 (0.97, 4.65), and for patients with TSH <0.4U/mL was 0.46 (0.22, 0.95). The OR for patients with fT4 > 16pmol/L was 2.10 (1.09, 4.06), and for patients with fT4 < 10pmol/L was 0.45 (0.20, 0.98). The OR for patients with fT3 > 5.5pmol/L was 0.39 (0.14, 1.28). The OR for patients with fT3 < 3pmol/L was 1.83 (0.25, 13.69). The average fT4/fT3 was 3.39 ± 0.206 for cases and 2.93 ± 0.467 for controls. The fT4/fT3 quotient was considered high if it was >3.3 (OR =6.00 (2.94, 12.25)).

Conclusion

In this study, a direct relationship between high levels of fT4 and malignancy was uncovered. Furthermore, low levels of TSH and fT4 increased the likelihood that a nodule was benign. In this study a fT4/fT3 ratio >3.3 increased the risk of malignancy by 3.6 times (p-value =0.0013).

Thyroid-Stimulating Hormone, Thyroid Hormones, and Risk of Papillary Thyroid Cancer: A Nested Case-Control Study

Background: The effects of thyroid-stimulating hormone (TSH) and thyroid hormones on the development of human papillary thyroid cancer (PTC) remain poorly understood.Methods: The study population consisted of 741 (341 women, 400 men) histologically confirmed PTC cases and 741 matched controls with prediagnostic serum samples stored in the Department of Defense Serum Repository. Concentrations of TSH, total T3, total T4, and free T4 were measured in serum samples. Conditional logistic regression models were used to calculate ORs and 95% confidence intervals (CI).Results: The median time between blood draw and PTC diagnosis was 1,454 days. Compared with the middle tertile of TSH levels within the normal range, serum TSH levels below the normal range were associated with an elevated risk of PTC among women (OR, 3.74; 95% CI, 1.53-9.19) but not men. TSH levels above the normal range were associated with an increased risk of PTC among men (OR, 1.96; 95% CI, 1.04-3.66) but not women. The risk of PTC decreased with increasing TSH levels within the normal range among both men and women (P_trend = 0.0005 and 0.041, respectively).Conclusions: We found a significantly increased risk of PTC associated with TSH levels below the normal range among women and with TSH levels above the normal range among men. An inverse association between PTC and TSH levels within the normal range was observed among both men and women.Impact: These results could have significant clinical implications for physicians who are managing patients with abnormal thyroid functions and those with thyroidectomy. Cancer Epidemiol Biomarkers Prev; 26(8); 1209-18. ©2017 AACR.

Higher risk for thyroid diseases in physicians than in the general population: a Taiwan nationwide population-based secondary analysis study

BACKGROUND

Physicians have high work stress, responsibility for night shifts and chances of exposure to medical radiation, which may increase the risk for thyroid diseases.

AIM

We conducted this study to assess the risk for thyroid diseases in physicians, which remain unclear.

DESIGN

We used a secondary analysis of the Taiwan National Health Insurance Research Database for this study.

METHODS

After excluding thyroid diseases occurring before 2006 and residents, physicians and general population were identified by matching with age and sex in 2009 in a 1:2 ratio. The risk for thyroid diseases was compared between the physicians and general population and among physicians by tracing their medical histories between 2006 and 2012.

RESULTS

In total, 28,649 physicians and 57,298 general population were identified. Physicians had a higher risk for overall thyroid diseases than the general population [odds ratio (OR): 1.27; 95% confidence interval (CI): 1.10-1.47], including individual thyroid disease: thyroid cancer (OR: 1.89; 95% CI: 1.22-2.95), hypothyroidism (OR: 1.64; 95% CI: 1.23-2.18) and thyroiditis (OR: 1.48; 95% CI: 1.00-2.19).

CONCLUSIONS

We showed that physicians had a significantly higher risk for thyroid diseases than the general population. This reminds us to pay more attention to thyroid diseases in physicians. Further studies about the underlying mechanisms are warranted.

A comprehensive review of regulatory test methods for endocrine adverse health effects

Development of new endocrine disruption-relevant test methods has been the subject of intensive research efforts for the past several decades, prompted in part by mandates in the 1996 Food Quality Protection Act (FQPA). While scientific understanding and test methods have advanced, questions remain on whether current scientific methods are capable of adequately addressing the complexities of the endocrine system for regulatory health and ecological risk assessments. The specific objective of this article is to perform a comprehensive, detailed evaluation of the adequacy of current test methods to inform regulatory risk assessments of whether a substance has the potential to perturb endocrine-related pathways resulting in human adverse effects. To that end,  approximately 42 existing test guidelines (TGs) were considered in the evaluation of coverage for endocrine-related adverse effects. In addition to evaluations of whether test methods are adequate to capture endocrine-related effects, considerations of further enhancements to current test methods, along with the need to develop novel test methods to address existing test method gaps are described. From this specific evaluation, up to 35 test methods are capable of informing whether a chemical substance perturbs known endocrine related biological pathways. Based on these findings, it can be concluded that current validated test methods are adequate to discern substances that may perturb the endocrine system, resulting in an adverse health effect. Together, these test methods predominantly form the core data requirements of a typical food-use pesticide registration submission. It is recognized, however, that the current state of science is rapidly advancing and there is a need to update current test methods to include added enhancements to ensure continued coverage and public health and environmental protection.

Insulin Resistance: Any Role in the Changing Epidemiology of Thyroid Cancer?

In the past few decades, the incidence of thyroid cancer (TC), namely of its papillary hystotype (PTC), has shown a steady increase worldwide, which has been attributed at least in part to the increasing diagnosis of early stage tumors. However, some evidence suggests that environmental and lifestyle factors can also play a role. Among the potential risk factors involved in the changing epidemiology of TC, particular attention has been drawn to insulin-resistance and related metabolic disorders, such as obesity, type 2 diabetes, and metabolic syndrome, which have been also rapidly increasing worldwide due to widespread dietary and lifestyle changes. In accordance with this possibility, various epidemiological studies have indeed gathered substantial evidence that insulin resistance-related metabolic disorders might be associated with an increased TC risk either through hyperinsulinemia or by affecting other TC risk factors including iodine deficiency, elevated thyroid stimulating hormone, estrogen-dependent signaling, chronic autoimmune thyroiditis, and others. This review summarizes the current literature evaluating the relationship between metabolic disorders characterized by insulin resistance and the risk for TC as well as the possible underlying mechanisms. The potential implications of such association in TC prevention and therapy are discussed.

Co-Existence of Thyroid Nodule and Thyroid Cancer in Children and Adolescents with Hashimoto Thyroiditis: A Single-Center Study

BACKGROUND

Currently, there is an inadequate number of studies on nodule and malignancy development in children and adolescents with Hashimoto thyroiditis (HT).

MATERIAL AND METHODS

Patients who were diagnosed with HT between 2004 and 2013 were included in the study. The HT diagnosis was made with a heterogeneous appearance on thyroid ultrasonography and the elevation of antithyroid peroxidase and/or anti-thyroglobulin antibodies. Fine-needle aspiration biopsy (FNAB) was performed in cases with a nodule size >1 cm or who had ultrasonography findings indicating malignancy.

RESULTS

A total of 39 (13%) thyroid nodules were detected in 300 patients with a diagnosis of HT. Papillary thyroid carcinoma (PTC) was diagnosed in 2 of the 12 cases in whom FNAB was performed. The thyroid nodule was detected at the same time as HT in the 2 cases with malignancy. The PTC diagnosis was made 2 years after the HT diagnosis in the first case and 3 years later in the second case. The largest diameter of the thyroid nodule was 5 mm in both cases.

CONCLUSION

The thyroid nodule rate on an HT background was found to be 13%, and the thyroid malignancy rate was 0.67% in our study.

WOMEN IN CANCER THEMATIC REVIEW: Thyroid-stimulating hormone in thyroid cancer: does it matter?

Differentiated thyroid cancer is the most common endocrine malignancy and the incidence is increasing rapidly worldwide. Appropriate diagnosis and post-treatment monitoring of patients with thyroid tumours are critical. Fine needle aspiration cytology remains the gold standard for diagnosing thyroid cancer, and although there have been significant refinements to this technique, diagnostic surgery is often required for patients suspected to have malignancy. Serum thyroid-stimulating hormone (TSH) is higher in patients with malignant thyroid nodules than in those with benign disease, and TSH is proportionally increased in more aggressive tumours. Importantly, we have shown that the pre-operative serum TSH concentration independently predicts the presence of malignancy in subjects presenting with thyroid nodules. Establishing the use of TSH measurements in algorithms identifying high-risk thyroid nodules in routine clinical practice represents an exciting, cost-efficient and non-invasive approach to optimise thyroid cancer diagnosis. Binding of TSH to receptors on thyrocytes stimulates a number of growth promoting pathways both in normal and malignant thyroid cells, and TSH suppression with high doses of levothyroxine is routinely used after thyroidectomy to prevent cancer recurrence, especially in high-risk tumours. This review examines the relationship between serum TSH and thyroid cancer and reflects on the clinical potential of TSH measurements in diagnosis and disease monitoring.

Papillary thyroid carcinoma risk factors in the Yunnan plateau of southwestern China

Objective

This study investigated clinical and pathological characteristics and risk factors in papillary thyroid carcinoma (PTC) patients’ native to Yunnan plateau in southwestern China.

Methods

Clinical data from 1,198 patients diagnosed with PTC (n=578) and control subjects (n=620) with benign thyroid disease (ie, thyroid nodule disease, benign thyroid diseases [BTD]) in Yunnan province were analyzed retrospectively.

Results

The mean patient age was lower for PTC than for BTD. Positive ratios of thyroid peroxidase antibody, thyroglobulin antibody (TGAb), and thyrotrophin receptor antibody (TRAb) were higher in PTC than in BTD patients. The ratio of PTC coexisting with Hashimoto’s thyroiditis (HT) or with lymphocytic thyroiditis was higher than that of BTD. The number of patients whose age at menarche was ≤13 years, who had given birth to less than or equal to two children, or who were in premenopause were higher in the PTC than in the BTD group. Multivariate conditional logistic regression analyses revealed that age >45 years, nodal size >1 cm, and elevated TG levels were protective factors against PTC. Abnormally elevated TGAb and TRAb levels were independent risk factors for PTC in females.

Conclusion

HT was not an independent risk factor for but was associated with PTC. TRAb is a risk factor for PTC in individuals living in the Yunnan plateau, but not for those in the plains region.

MAPK and SHH pathways modulate type 3 deiodinase expression in papillary thyroid carcinoma

Type 3 deiodinase (DIO3, D3) is reactivated in human neoplasias. Increased D3 levels in papillary thyroid carcinoma (PTC) have been associated with tumor size and metastatic disease. The objective of this study is to investigate the signaling pathways involved in DIO3 upregulation in PTC. Experiments were performed in human PTC cell lines (K1 and TPC-1 cells) or tumor samples. DIO3 mRNA and activity were evaluated by real-time PCR and ion-exchange column chromatography respectively. Western blot analysis was used to determine the levels of D3 protein. DIO3 gene silencing was performed via siRNA transfection. DIO3 mRNA levels and activity were readily detected in K1 (BRAF(V6) (0) (0E)) and, at lower levels, in TPC-1 (RET/PTC1) cells (P<0.007 and P=0.02 respectively). Similarly, DIO3 mRNA levels were higher in PTC samples harboring the BRAF(V600E) mutation as compared with those with RET/PTC1 rearrangement or negative for these mutations (P<0.001). Specific inhibition of BRAF oncogene (PLX4032, 3 μM), MEK (U0126, 10-20 μM) or p38 (SB203580, 10-20 μM) signaling was associated with decreases in DIO3 expression in K1 and TPC-1 cells. Additionally, the blockage of the sonic hedgehog (SHH) pathway by cyclopamine (10  μM) resulted in markedly decreases in DIO3 mRNA levels. Interestingly, siRNA-mediated DIO3 silencing induced decreases on cyclin D1 expression and partial G1 phase cell cycle arrest, thereby downregulating cell proliferation. In conclusion, sustained activation of the MAPK and SHH pathways modulate the levels of DIO3 expression in PTC. Importantly, DIO3 silencing was associated with decreases in cell proliferation, thus suggesting a D3 role in tumor growth and aggressiveness.

Diabetes, Diabetes Treatment, and Risk of Thyroid Cancer

OBJECTIVE

The objective of this study was to assess the relationships among diabetes, diabetes treatment and thyroid cancer risk using a large prospective cohort, the Women's Health Initiative.

METHODS

A total of 147 934 women who were free of known cancer at baseline were followed prospectively. Diabetes status and diabetes treatment at baseline and during follow-up were ascertained. Incident cases of thyroid cancers were confirmed by physician review of central medical records and pathology reports. Time-dependent Cox proportional hazards regressions were used to estimate hazard ratios and 95% confidence intervals for thyroid cancer risk associated with diabetes status, diabetes treatment, and duration of diabetes.

RESULTS

With a median follow-up time of 15.9 years, 391 incident thyroid cancers were identified. We found no significant associations between thyroid cancer and diabetes (hazard ratio = 1.09; 95% confidence interval, 0.79-1.52), diabetes treatment, or duration of diabetes.

CONCLUSION

Our findings do not support the hypothesis that diabetes, or treatment of diabetes is associated with risk of thyroid cancer among postmenopausal women. Studies to investigate the specific effects of hyperinsulinemia and insulin resistance on thyroid cancer risk may provide additional information.

Thyroid Hormones, Autoantibodies, Ultrasonography, and Clinical Parameters for Predicting Thyroid Cancer

Our objective was to evaluate thyroid nodule malignancy prediction using thyroid function tests, autoantibodies, ultrasonographic imaging, and clinical data. We conducted a retrospective cohort study in 1400 patients with nodular thyroid disease (NTD). The thyroid stimulating hormone (TSH) concentration was significantly higher in patients with differentiated thyroid cancer (DTC) versus benign thyroid nodular disease (BTND) (p = 0.004). The receiver operating characteristic curve of TSH showed an AUC of 0.58 (95% CI 0.53-0.62, p = 0.001), sensitivity of 74%, and specificity of 57% at a cut-off of 1.59 mIU/L. There was an incremental increase in TSH concentration along with the increasing tumor size (p < 0.001). Thyroglobulin antibody (TgAb) concentration was associated with an increased risk of malignancy (p = 0.029), but this association was lost when the effect of TSH was taken into account (p = 0.11). Thyroid ultrasonographic characteristics, including fewer than three nodules, hypoechoic appearance, solid component, poorly defined margin, intranodular or peripheral-intranodular flow, and punctate calcification, can be used to predict the risk of thyroid cancer. In conclusion, our study suggests that preoperative serum TSH concentration, age, and ultrasonographic features can be used to predict the risk of malignancy in patients with NTD.

Iodine, thyroid autoimmunity and cancer

This review focuses on two different topics: (a) iodine and autoimmune thyroid disease (AITD) and (b) AITD and papillary thyroid carcinoma (PTC). Iodine intake modifies the expression of thyroid diseases and has been associated with induction of AITD. Thyroglobulin (Tg) is an important target in iodine-induced autoimmune response due to post-translational modifications of iodinated Tg, as suggested in animal models. We have shown that the unmasking of a cryptic epitope on Tg contributes to iodine-induced thyroid autoimmunity in humans. The relationship between AITD and PTC has been suggested in many studies. The presence of two different mechanisms has been hypothesized, one typical of AITD and the other of an immune reaction to PTC. We have shown that in AITD, the pattern of Tg recognition by anti-Tg antibodies (TgAb) is 'restricted' to the immunodominant regions of Tg, while in patients with non-AITD, such as nodular goiter and PTC devoid of thyroid lymphocytic infiltration at histology, TgAb show a less restricted epitopic pattern and bind also to other regions of Tg. Thyroid function may also affect the frequency of PTC, the risk of cancer increasing with serum TSH levels. We have shown that this mechanism, rather than thyroiditis per se, plays a major role in the association of PTC with Hashimoto's thyroiditis, as a consequence of the autoimmune process leading to a progressive increase of serum TSH in these patients.

Occupation and thyroid cancer

Numerous occupational and environmental exposures have been shown to disrupt thyroid hormones, but much less is known about their relationships with thyroid cancer. Here we review the epidemiology studies of occupations and occupational exposures and thyroid cancer incidence to provide insight into preventable risk factors for thyroid cancer. The published literature was searched using the Web of Knowledge database for all articles through August 2013 that had in their text 'occupation' 'job' 'employment' or 'work' and 'thyroid cancer'. After excluding 10 mortality studies and 4 studies with less than 5 exposed incident cases, we summarised the findings of 30 articles that examined thyroid cancer incidence in relation to occupations or occupational exposure. The studies were grouped by exposure/occupation category, study design and exposure assessment approach. Where available, gender-stratified results are reported. The most studied (19 of 30 studies) and the most consistent associations were observed for radiation-exposed workers and healthcare occupations. Suggestive, but inconsistent, associations were observed in studies of pesticide-exposed workers and agricultural occupations. Findings for other exposures and occupation groups were largely null. The majority of studies had few exposed cases and assessed exposure based on occupation or industry category, self-report, or generic (population-based) job exposure matrices. The suggestive, but inconsistent findings for many of the occupational exposures reviewed here indicate that more studies with larger numbers of cases and better exposure assessment are necessary, particularly for exposures known to disrupt thyroid homeostasis.

Evaluation of serum thyroid-stimulating hormone as indicator for fine-needle aspiration in patients with thyroid nodules

BACKGROUND

Recently, it has been reported that the risk of thyroid malignancy increases with increasing concentrations of serum thyroid-stimulating hormone (TSH). The purpose of this study was to determine whether or not serum TSH can be a predictor for thyroid malignancy when considering the relevant ultrasound features and clinical risk factors.

METHODS

This retrospective study included 1200 euthyroid patients with 1269 thyroid nodules who underwent ultrasound-guided fine-needle aspiration (FNA) biopsy between January and June 2009. Serum TSH, ultrasound feature, and clinical parameters were compared according to final diagnosis. Subgroup analyses were performed according to nodule size.

RESULTS

Serum TSH did not show a positive association with malignancy for all nodules and the micronodule subgroup in multivariate analysis, although they showed significant association with thyroid malignancy for the macronodule subgroup. For all nodules and the 2 subgroups, suspicious ultrasound features and younger age were significantly associated with malignancy in univariate and multivariate analyses.

CONCLUSION

Our study suggests that TSH alone is not as useful as ultrasound features in deciding whether or not to perform FNA in patients with micronodules.

Thyrotropin values in patients with micropapillary thyroid cancer versus benign nodular disease

OBJECTIVE

Studies published in the last few years suggest that increased thyroid-stimulating hormone (TSH) values are associated with increased risk of thyroid cancer and/or a more advanced stage of malignancy. The aim of this study was to explore the hypothesis that TSH may be a risk factor for thyroid cancer initiation, which was tested by comparing TSH concentrations in patients with incidental micro papillary cancer (mPTC) and controls with a negative histologic exam.

METHODS

Patients were retrospectively selected from medical records from 3 district hospitals. Patients with biochemical/histologic evidence of autoimmunity, thyroid function-interfering drugs, and autonomously functioning areas, were excluded. TSH values of 41 patients with an incidental mPTC were then compared with a sex- and age-matched group of patients who had a negative histologic exam at a 4:1 ratio (164 patients).

RESULTS

TSH was not significantly different in the mPTC group compared to the controls (1.1 ± 0.7 vs. 1.3 ± 1.0 mIU/L). After adjustment for age and gender, TSH levels were still not found to be significantly different between groups. In the mPTC group, TSH levels were not found to be a significant predictor of tumor size after adjusting for age and gender (β = 0.035, SE = 0.73, P = .844).

CONCLUSIONS

On the basis of these results, the hypothesis that TSH is involved in de novo oncogenesis of PTC is not supported.

Obesity and thyroid cancer: epidemiologic associations and underlying mechanisms

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.

Clinical implications of preoperative thyrotropin serum concentrations in patients who underwent thyroidectomy for nonfunctioning nodule(s)

Purpose

Thyroid stimulating hormone (TSH) measurement is the most sensitive screening test for thyroid dysfunction. TSH is a well-known thyroid growth factor but its pathogenic role in thyroid oncogenesis remains to be clarified. The purpose of the present study was to evaluate the relationship between clinicopathologic characteristics of nonfunctioning thyroid nodules and preoperative TSH serum concentrations.

Methods

Serum TSH concentrations can be affected by many factors. After exclusion of these confounding factors, a total of 126 patients who underwent thyroidectomy from Januray 2009 to December 2010 were included in this study. Average age was 45.4 ± 10.6 years and male:female ratio was 1:2.9. There were 11 patients with benign nodules, 34 patients with papillary thyroid microcarcinoma (PTMC) of less than 5 mm in maximal diameter, 66 patients with PTMCs of more than 5 mm but not more than 10 mm in maximal diameter, and 15 patients with papillary thyroid carcinoma (PTC) of more than 10 mm in maximal diameter.

Results

TNM stages of PTCs correlated with higher preoperative TSH serum concentrations. There were trends of higher preoperative TSH serum concentrations in patients who had extrathyroidal extension (P = 0.059) and advanced N stages (P = 0.120) but did not reach statistical significance. Patients' age, sex, and tumor volume did not seem to affect preoperative TSH serum concentrations significantly.

Conclusion

In patients who have PTCs without clinical, immunological, or ultrasonographic evidence of thyroiditis, higher preoperative TSH serum concentrations within the normal range might suggest advanced TNM stages.

Lack of association between high serum thyroid-stimulating hormone level and risk of papillary thyroid microcarcinomas

BACKGROUND

High serum thyroid-stimulating hormone (TSH) is associated with thyroid carcinoma in patients with thyroid nodules. However, previous studies suggests that TSH is not involved in the pathogenesis of small thyroid carcinomas. We performed this study to evaluate serum TSH as a malignancy predictor in the assessment of small thyroid nodules.

METHODS

We retrospectively analyzed 3791 patients who underwent thyroidectomy. We classified all patients into 3 to 5 groups by serum TSH or nodule size and analyzed the association of serum TSH and risk of papillary thyroid carcinoma (PTC).

RESULTS

The frequency of PTC increased as serum TSH increased. Serum TSH and older age were associated with the risk of PTC in multivariate analysis (p < .0001). In subgroup analysis, the risk of PTC increased as serum TSH increased with thyroid nodules > 1 cm (p < .05).

CONCLUSIONS

Serum TSH may not be useful for clinical risk assessment of small thyroid nodules.

Hashimoto's thyroiditis, microcalcification and raised thyrotropin levels within normal range are associated with thyroid cancer

BACKGROUND

To confirm whether clinical and biochemical parameters or Hashimoto's thyroiditis (HT) could predict the risks of malignancy among subjects who underwent thyroidectomy, as well as to determine the influence of HT on the biological behavior of papillary thyroid cancer (PTC).

METHODS

A total of 2,052 patients who underwent initial thyroidectomy were enrolled between June 2006 and August 2008. Serum free T4, free T3, thyrotropin (TSH), thyroglobulin, thyroglobulin antibody, antimicrosomal antibody, tumor-associated status, and thyroid disorders were documented.

RESULTS

Binary logistic regression analysis was performed to define the risk predictors for thyroid cancer. Finally, calcification, HT, TSH, and age, were entered into the multivariate model. Multivariate logistic regression analysis revealed the risk of thyroid cancer increases in parallel with TSH concentration within normal range, and the risk for malignancy significantly increased with serum TSH 1.97-4.94 mIU/L, compared with TSH less than 0.35 mIU/L (OR = 1.951, 95% CI = 1.201-3.171, P = 0.007). Increased risks of thyroid cancer were also detected among the patients with HT (OR = 3.732, 95% CI = 2.563-5.435), and microcalcification (OR = 14.486, 95% CI = 11.374-18.449). The effects of HT on the aggressiveness of PTC were not observed in extrathyroidal invasion (P = 0.347), capsular infiltration (P = 0.345), angioinvasion (P = 0.512), and lymph node metastases (P = 0.634).

CONCLUSIONS

The risk of malignancy increases in patients with higher level TSH within normal range, as well as the presence of HT and microcalcification. No evidence suggests that coexistent HT alleviates the aggressiveness of PTC.

Sleep disturbance and incidence of thyroid cancer in postmenopausal women the Women's Health Initiative

Sleep disturbance has been found to be associated with numerous adverse health outcomes, including cancers. However, no epidemiologic study has examined the relation between sleep disturbance and thyroid cancer risk. A total of 142,933 postmenopausal women who were 50-79 years of age and enrolled in the Women's Health Initiative between September 1, 1993, and December 31, 1998, were followed up for a mean of 11 years. Cox proportional-hazard regression models were used to estimate hazard ratios and 95% confidence intervals for sleep disturbance (insomnia and sleep duration) and risk of thyroid cancer. Insomnia score was measured using a validated 5-item Women's Health Initiative Insomnia Rating Scale. Overall, a total of 295 thyroid cancer cases were identified. After adjustment for potential confounders, women with greater insomnia scores had a significantly higher risk of thyroid cancer than did women with low scores (hazard ratio = 1.44, 95% confidence interval: 1.01, 2.05). The significant association between insomnia score and thyroid cancer was confined to nonobese women (hazard ratio = 1.71, 95% confidence interval: 1.12, 2.62) and was not seen in obese women (hazard ratio = 0.94 95% confidence interval: 0.48, 1.84) (P for interaction = 0.07). In conclusion, postmenopausal women with greater insomnia scores, especially nonobese women, had a significantly increased risk of thyroid cancer. More studies are needed to confirm these findings.

The clinical features of papillary thyroid cancer in Hashimoto's thyroiditis patients from an area with a high prevalence of Hashimoto's disease

Background

The goal of this study was to identify the clinicopathological factors of co-existing papillary thyroid cancer (PTC) in patients with Hashimoto’s thyroiditis (HT) and provide information to aid in the diagnosis of such patients.

Methods

This study included 6109 patients treated in a university-based tertiary care cancer hospital over a 3-year period. All of the patients were categorised based on their final diagnosis. Several clinicopathological factors, such as age, gender, nodular size, invasive status, central compartment lymph node metastasis (CLNM) and serum thyroid-stimulating hormone (TSH) level, were compared between the various groups of patients.

Results

There were 653 patients with a final diagnosis of HT. More PTC was found in those with HT (58.3%; 381 of 653) than those without HT (2416 of 5456; 44.3%; p < 0.05). The HT patients with co-occurring PTC were more likely to be younger, be female, have smaller nodules and have higher TSH levels than those without PTC. A multivariate analysis indicated that the presence of HT and higher TSH levels were risk factors for a diagnosis of PTC. In the PTC patients, the presence of HT or another benign nodule was a protective factor for CLNM, whereas no significant association was found for TSH levels.

Conclusion

PTC and HT have a close relationship in this region of highly prevalent HT disease. Based on the results of our study, we hypothesise that long-term HT leads to elevated serum TSH, which is the real risk factor for thyroid cancer.

Diabetes and thyroid cancer risk: literature review

Diabetic patients have a higher risk of various types of cancer. However, whether diabetes may increase the risk of thyroid cancer has not been extensively studied. This paper reviews and summarizes the current literature studying the relationship between diabetes mellitus and thyroid cancer, and the possible mechanisms linking such an association. Epidemiologic studies showed significant or nonsignificant increases in thyroid cancer risk in diabetic women and nonsignificant increase or no change in thyroid cancer risk in diabetic men. A recent pooled analysis, including 5 prospective studies from the USA, showed that the summary hazard ratio (95% confidence interval) for women was 1.19 (0.84-1.69) and was 0.96 (0.65-1.42) for men. Therefore, the results are controversial and the association between diabetes and thyroid cancer is probably weak. Further studies are necessary to confirm their relationship. Proposed mechanisms for such a possible link between diabetes and thyroid cancer include elevated levels of thyroid-stimulating hormone, insulin, glucose and triglycerides, insulin resistance, obesity, vitamin D deficiency, and antidiabetic medications such as insulin or sulfonylureas.