Serum TSH and risk of papillary thyroid cancer in nodular thyroid disease

Relationship between serum vitamin D levels and thyroid- and parathyroid-related diseases: a Mendelian randomisation study

Previous studies have indicated an association between vitamin D and thyroid- and parathyroid-related diseases. However, it remains unclear whether it is a cause of the disease, a side effect of treatment or a consequence of the disease. The Mendelian randomisation (MR) study strengthens the causal inference by controlling for non-heritable environmental confounders and reverse causation. In this study, a two-sample bidirectional MR analysis was conducted to investigate the causal relationship between serum vitamin D levels and thyroid- and parathyroid-related diseases. Inverse variance weighted, weighted median and MR-Egger methods were performed, the Cochran Q test was used to evaluate the heterogeneity and the MR-PRESSO and MR-Egger intercepts were utilised to assess the possibility of pleiotropy. The Bonferroni-corrected significance threshold was 0·0038. At the Bonferroni-corrected significance level, we found that vitamin D levels suggestively decreased the risk of benign parathyroid adenoma (OR = 0·244; 95 % CI 0·074, 0·802; P = 0·0202) in the MR analyses. In the reverse MR study, a genetically predicted risk of thyroid cancer suggestively increased the risk of elevated vitamin D (OR = 1·007; 95 % CI 1·010, 1·013; P = 0·0284), chronic thyroiditis significantly increased the risk of elevated vitamin D (OR = 1·007; 95 % CI 1·002, 1·011; P = 0·0030) and thyroid nodules was significantly decreased the vitamin D levels (OR = 0·991; 95 % CI 0·985, 0·997; P = 0·0034). The findings might be less susceptible to horizontal pleiotropy and heterogeneity (P > 0·05). This study from a gene perspective indicated that chronic thyroiditis and thyroid nodules may impact vitamin D levels, but the underlying mechanisms require further investigation.

The Role of Body Mass Index (BMI) in Differentiated Thyroid Cancer: A Potential Prognostic Factor?

Obesity has been recognized as a potential risk factor for the carcinogenesis of differentiated thyroid cancer (DTC). The aim of this observational study was to investigate the prognostic role of BMI in influencing DTC histopathological aggressiveness and the risk of tumor relapse. We enrolled 257 patients with DTC, consecutively admitted to our Institution between January 2016 and December 2023. The following variables were collected: demographic, anthropometric and clinical parameters, risk factors for DTC, surgical and radioiodine therapy, histopathological features of DTC, and biochemical markers of disease. Tumor recurrence was assessed during short-, medium- and long-term follow-up. According to BMI tertiles (e.g; I: BMI < 23.3 kg/m2; II: 23.3 ≤ BMI < 27.1 kg/m2; III: BMI ≥ 27.1 kg/m2), the clinical and histopathological characteristics did not differ between groups. The multinomial logistic regression analysis showed that BMI was not associated with clinical and histopathological aggressiveness of DTC, independently from sex, age, and risk factors for DTC onset. Moreover, BMI did not constitute a predictor of tumor recurrence during follow-up. In conclusion, BMI does not represent a predictor of clinical and histopathological aggressiveness of DTC. Since it is not a reliable marker of adiposity, BMI cannot be considered alone in evaluating the potential association between obesity and DTC prognosis.

Clinical risk factors and cancer risk of thyroid imaging reporting and data system category 4 A thyroid nodules

PURPOSE

Beyond the Thyroid Imaging Reporting and Data System (TIRADS) classification of thyroid nodules, additional factors must be weighed in the decision to perform fine needle aspiration (FNA). In this study, we aimed to identify risk factors for malignancy in patients with ultrasound-classified Chinese-TIRADS (C-TIRADS) 4 A nodules.

METHODS

Patients who underwent thyroid FNA at our institution between May 2021 and September 2022 were enrolled. We collected demographic data, including age, sex, previous radiation exposure, and family history. An in-person questionnaire was used to collect lifestyle data, such as smoking habits and alcohol consumption. Body mass index (BMI) was calculated. The serum levels of thyroid stimulating hormone (TSH), thyroid peroxidase antibody (TPOAb), and thyroglobulin antibody (TGAb) were measured. Prior to FNA, ultrasonic inspection reports were reviewed. The cytologic diagnoses for FNA of thyroid nodules followed the Bethesda System for Reporting Thyroid Cytopathology (2017).

RESULTS

Among the 252 C-TIRADS 4 A nodules, 103 were malignant. Compared to those in the benign group, the patients in the malignant group had a younger age (42.2 ± 13.6 vs. 51.5 ± 14.0 years, P < 0.001). Logistic regression showed that advanced age was associated with a lower risk of malignancy in C-TIRADS 4 A nodules (OR = 0.95, 95% CI 0.93 ~ 0.97, P < 0.001). We demonstrated a decreased risk of malignancy in patients with 48.5 years or older.

CONCLUSION

Advanced age was associated with a decreased risk of malignancy in patients with C-TIRADS 4 A nodules. This study indicated that in addition to sonographic characteristics, patient age should be considered when assessing the risk of malignancy.

Association Between Eight Autoimmune Diseases and Thyroid Cancer: A Nationwide Cohort Study

Background: It has often been reported that thyroid-specific autoimmune diseases (ADs), such as Hashimoto's thyroiditis and Graves' disease, could increase the risk of thyroid cancer, but the association between other ADs beyond thyroid and thyroid cancer has not been well investigated. This study aimed to examine the risk of thyroid cancer in patients with eight ADs compared with those without ADs. Methods: This nationwide retrospective matched cohort study was conducted to investigate the relationship of eight ADs (Hashimoto's thyroiditis, Graves' disease, type 1 diabetes mellitus, Sjogren's disease, inflammatory bowel disease [IBD], vitiligo, systemic lupus erythematosus, and rheumatoid arthritis [RA]) with the risk of incident thyroid cancer using the National Health Insurance Service-National Sample Cohort. The Cox-proportional hazard model was used to estimate the adjusted hazard ratio (HR) and confidence intervals (CI) for thyroid cancer in relation to each of AD compared with control group without AD. Results: During the average follow-up of 9.49 years, 138 thyroid cancer cases were newly developed in control group and 268 cases were occurred in group with 8 ADs. For all of study participants, the risk of thyroid cancer was significantly increased in patients with Hashimoto's thyroiditis (HR = 2.10 [1.57-2.81]), Graves' disease (HR = 2.67 [1.99-3.62]), IBD (HR = 2.06 [1.50-2.83]), vitiligo (HR = 1.71 [1.13-2.59]), RA (HR = 1.76 [1.07-2.90]), and total of 8 ADs (HR = 1.97 [1.60-2.42]) compared with control group without ADs. When ADs were divided into three types, thyroid-specific ADs (HR = 2.37 [1.85-3.03]) showed the strongest and significant association with thyroid cancer, followed by local ADs (HR = 1.83 [1.41-2.38]), and systemic ADs (HR = 1.77 [1.14-2.74]). Conclusions: Specific ADs-especially for thyroid-specific AD, vitiligo, IBD, and RA-were associated with increased risk for thyroid cancer.

Cuproptosis-related lncRNAs predict prognosis and immune response of thyroid carcinoma

Objective: To estimate the survival and prognosis of patients with thyroid carcinoma (THCA) based on the Long non-coding RNA (lncRNA) traits linked to cuproptosis and to investigate the connection between the immunological spectrum of THCA and medication sensitivity. Methods: RNA-Seq data and clinical information for THCA were obtained from the Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases. We built a risk prognosis model by identifying and excluding lncRNAs associated with cuproptosis using Cox regression and LASSO methods. Both possible biological and immune infiltration functions were investigated using Principal Component Analysis (PCA), Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), and immunoassays. The sensitivity of the immune response to possible THCA medicines was assessed using ratings for tumor immune dysfunction and exclusion (TIDE) and tumor mutational burden (TMB). Results: Seven cuproptosis-related lncRNAs were used to construct our prognostic prediction model: AC108704.1, DIO3OS, AL157388.1, AL138767.3, STARD13-AS, AC008532.1, and PLBD1-AS1. Using data from TCGA's training, testing, and all groups, Kaplan-Meier and ROC curves demonstrated this feature's adequate predictive validity. Different clinical characteristics have varying effects on cuproptosis-related lncRNA risk models. Further analysis of immune cell infiltration and single sample Gene Set Enrichment Analysis (ssGSEA) supported the possibility that cuproptosis-associated lncRNAs and THCA tumor immunity were closely connected. Significantly, individuals with THCA showed a considerable decline in survival owing to the superposition effect of patients in the high-risk category and high TMB. Additionally, the low-risk group had a higher TIDE score compared with the high-risk group, indicating that these patients had suboptimal immune checkpoint blocking responses. To ensure the accuracy and reliability of our results, we further verified them using several GEO databases. Conclusion: The clinical and risk aspects of cuproptosis-related lncRNAs may aid in determining the prognosis of patients with THCA and improving therapeutic choices.

Diagnostic Scrutiny and Patterns of Elevated Cancer Risk: Uncovering Overdiagnosis Through Standardized Incidence Ratios

Certain medical diagnoses and environmental or occupational exposures may be associated with elevated risk of cancer diagnosis, either through causal mechanisms or via increased detection of a subclinical reservoir through increased diagnostic scrutiny (overdiagnosis). The present study aimed to investigate the distribution of elevated cancer risks associated with different diagnoses and exposures. A systematic literature search was conducted to identify studies published in the last 30 years that examined the standardized incidence ratio (SIR) associated with exposures and risk factors. Meta-SIRs for each cancer type were calculated. The distribution of elevated cancer risks was then compared between cancer types previously reported to be susceptible to overdiagnosis and those that have not been associated with overdiagnosis. The review of 108 studies identified four patterns: SIR generally elevated for 1) only overdiagnosis-susceptible cancer types, 2) both overdiagnosed and non-overdiagnosed cancer types, 3) select cancers in accordance with risk factor or exposure, and 4) SIRs that did not exhibit a distinct increase in any cancer type. The distribution of elevated cancer risks may serve as a signature of whether the underlying risk factor or exposure is a carcinogenic process or a mechanism of increased diagnostic scrutiny uncovering clinically occult diseases. The identification of increased cancer risk should be viewed with caution, and analyzing the pattern of elevated cancer risk distribution can potentially reveal conditions that appear to be cancer risk factors but are in fact the result of exposure to medical surveillance or other healthcare activities that lead to the detection of indolent tumors.

TSH level as a risk factor of thyroid malignancy for nodules in euthyroid patients

Objective

With the increased prevalence of incidental thyroid cancer, determining the predictors of thyroid malignancy has become a source of debate. This study aimed to determine the impact of thyroid stimulating hormone (TSH) levels on rates of thyroid cancer in euthyroid patients.

Methods

A retrospective study included 421 patients who underwent thyroidectomy at a tertiary hospital between 2016 and 2020. Patients' demographics, history of cancer, pre-operative workup and final histology reports were obtained. The study sample was divided into two groups based on the final histopathology (benign vs malignant). The two groups were compared using the appropriate statistical tests to determine the predictors of thyroid cancer in euthyroid patients.

Results

TSH levels were significantly higher in patients with malignant nodules compared to those with benign nodules (1.94 vs 1.62, p = 0.002). It was 1.54 times more likely for thyroid nodules to be malignant when TSH levels were higher (p = 0.038). Meanwhile, larger nodules (> 4 cm) were significantly more prevalent in benign nodules (43.1%) than in malignant nodules (21.1%). Larger nodules decreased the possibility of thyroid cancer by 24% (OR = 0.760, p-value = 0.004).

Conclusions

High TSH levels in euthyroid patients were significantly correlated with the risk of thyroid malignancy. In addition, as Bethesda category proceeded toward malignancy, TSH levels increased. High TSH levels and small nodule diameters can be used as additional parameters in predicting thyroid cancer in euthyroid patients.

Comparison of Various Ultrasound-Based Malignant Risk Stratification Systems on an Occasion for Assessing Thyroid Nodules in Hashimoto's Thyroiditis

Purpose

To compare the diagnostic performance and unnecessary ultrasound-guided fine-needle aspiration (US-FNA) biopsy rate of the 2015 American Thyroid Association (ATA), 2016 Korean Society of Thyroid Radiology (KSThR), and 2017 American College of Radiology (ACR) guidelines for patients with and without Hashimoto's thyroiditis (HT).

Patients and Methods

This retrospective study included 716 nodules from 696 consecutive patients, which were classified using the categories defined by the three guidelines: ATA, KSThR, and ACR. The malignancy risk in each category was calculated and the diagnostic performance and unnecessary fine-needle aspiration (FNA) rates of the three guidelines were compared.

Results

In total, 426 malignant and 290 benign nodules were identified. Patients with malignant nodules had lower total thyroxine levels and higher thyroid-stimulating hormone, thyroid peroxidase antibody, and thyroglobulin antibody levels than those without malignant nodules (all P<0.01). The margin difference was significant in non-HT patients (P<0.01), but comparable in HT patients (P=0.55). The calculated malignancy risks of high and intermediate suspicion nodules in the ATA and KSThR guidelines and moderately suspicious nodules in the ACR guidelines were significantly lower in non-HT patients compared with HT patients (P<0.05). The ACR guidelines showed the lowest sensitivity, highest specificity, and lowest unnecessary FNA rates in patients with and without HT. Compared to non-HT patients, HT patients had significantly lower unnecessary FNA rates (P<0.01).

Conclusion

HT was associated with a higher malignancy rate of thyroid nodules with intermediate suspicion according to the ATA, KSThR, and ACR guidelines. The three guidelines, especially ACR, were likely to be more effective and could allow a greater reduction in the percentage of benign nodules biopsied in patients with HT.

Exposure to Bisphenol A increases malignancy risk of thyroid nodules in overweight/obese patients

Bisphenol A (BPA) is a widespread thyroid disruptor, but evidence about an association with thyroid cancer is weak. Excess body weight is a risk factor for thyroid cancer and affects activity of endocrine disruptors. Aim of the study was to investigate the association between BPA exposure and thyroid cancer, verifying the effect modification related to body weight. We performed a multicentre, cross-sectional study including consecutive patients referring for nodular goiter. The quantitative determination of BPA in serum samples was performed through high performance liquid chromatography system, coupled in tandem with ultraviolet and fluorescence detection. Ninety-six patients were included: 55 benign nodules, 41 thyroid cancers, 28 normal weight, and 68 overweight/obese. BPA was detected in 79 subjects. In the overall study population and in the group with BMI<25 kg/m² BPA exposure was not significantly correlated to thyroid cancer (p = 0.08 and 0.759, respectively). In the group with BMI≥25 kg/m², BPA-exposed subjects showed significantly higher risk of malignancy (OR: 5.3, p = 0.028). At multivariate analysis, such association was independent of smoking, alcohol consumption, occupational exposure, and phthalates exposure (p = 0.021 and 0.016, respectively), but was lost after adjustment for the presence of metabolic syndrome (p = 0.089). In overweight/obese subjects, BPA exposure was significantly associated with higher thyroid stimulating hormone levels. Our study suggests that BPA exposure is a risk factor for thyroid cancer in overweight/obese subjects.

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.

Possible Association Between Thyroid Nodule Formation and Developmental Alterations in the Pituitary-Thyroid Hormone Axis in Children and Adolescents: The Fukushima Health Management Survey

Background: We previously found low thyrotropin (TSH) levels in children and adolescents with thyroid nodules, including papillary thyroid cancer, although it is generally accepted that high TSH levels are a risk factor for formation and growth of thyroid nodules in adults. To clarify the reasons for the discrepancy, we precisely analyzed the features of pituitary-thyroid hormone (TH) actions in children and adolescents with or without nodules at different ages. Methods: Among the 4955 participants who participated in a second screening by thyroid ultrasound examination in the Fukushima Health Management Survey, 721 and 2849 euthyroid participants aged 6-20 years without or with nodules, including thyroid cancer, were selected for evaluation of TH regulation. The responsivity of TSH to THs was assessed by two thyroid feedback quantile-based indices (T4FQI and T3FQI). Logistic regression analyses were conducted to calculate the odds ratios (ORs) of serum concentrations related to thyroid functions for positive thyroid nodules compared with negative nodules. Results: The feedback indices declined in a sex-specific manner with aging. In particular, T3FQI, the index for TSH response to free triiodothyronine (fT3), started to decline after ∼10 and 15 years of age in female and male participants, respectively. Compared with the absence of nodules, the age- and sex-adjusted ORs (confidence intervals) for logTSH, free thyroxine (fT4), fT3, T4FQI, T3FQI, and thyroglobulin levels were 0.586 (0.501-0.685), 1.036 (0.595-1.805), 1.059 (0.842-1.332), 0.569 (0.454-0.715), 0.564 (0.443-0.719), and 1.01 (1.005-1.014), respectively. Associations between the presence of nodules and either low logTSH or low feedback indices were observed in participants aged between 12 and 17 years among the total cohort. Conclusions: The relationships between the levels of TSH and THs changed in a sex-dependent manner in children and adolescents. The age-dependent shift in the pituitary-TH set point may be associated with age-dependent nodule formation during restricted periods of growth and maturation in both young female and male participants.

Clinical usefulness of thyroid ultrasonography in patients with primary hypothyroidism

BACKGROUND AND OBJECTIVE

Despite the value of ultrasonography in the detection of chronic thyroiditis (CT) as well as in nodular goitre, it is often only indicated in patients with hypothyroidism if a palpable goitre or a thyroid mass is identified. The objective of the study is to evaluate the clinical usefulness of thyroid ultrasonography in patients with primary hypothyroidism without clinical suspicion of nodular goitre. And more specifically, to analyse its value in the aetiological diagnosis of hypothyroidism, and to evaluate its contribution in the detection and characterisation of coexisting subclinical thyroid nodular disease.

PATIENTS AND METHOD

Prospective cross-sectional observational study of 114 patients with primary hypothyroidism of CT or idiopathic aetiology, without symptoms or cervical palpation suspected of nodular goitre, who underwent a thyroid function test, a serological study of antithyroid antibodies, a thyroid ultrasonound and, when appropriate, a cytological study of the nodules found.

RESULTS

Ultrasonound allowed CT to be recognised as the cause of hypothyroidism in 19% of patients who had a negative serological study, and detected nodules larger than 9mm in 22 patients (16 with antithyroid antibodies). A cytological study was performed in 18 of the cases. Five patients underwent surgery, with carcinoma found in two of them.

CONCLUSIONS

Thyroid ultrasound is useful in the aetiological diagnosis of primary hypothyroidism as well as in the detection of a coexisting, unsuspected, but clinically relevant nodular goitre, so this examination should be indicated in the initial study of patients with primary hypothyroidism.

Understanding the effect of obesity on papillary thyroid cancer: is there a need for tailored diagnostic and therapeutic management?

INTRODUCTION

Several studies have focused on the relationship between obesity and differentiated thyroid carcinoma (DTC), particularly papillary histotype (PTC). However, the association of obesity with both incidence and aggressiveness of PTC is still incompletely understood.

AREAS COVERED

We reviewed the mechanisms underlying the cross talk between obesity and thyroid carcinomas and described the most recent evidence evaluating the effect of obesity on the development of PTC, as well as the impact of excessive body weight on the clinicopathologic features and outcome of this type of cancer.

EXPERT OPINION

Available evidence suggests that excessive body weight is linked with a higher risk of getting PTC, while its impact on the aggressiveness of the disease, if present, is still not clear. Therefore, while attention should be paid to discover thyroid cancer in patients with obesity earlier, once diagnosed it should be managed following a conventional workup as in normal weight patients, based on the clinical presentation of the disease and including active surveillance if appropriate, as recommended by referral guidelines.

Thyroid Cancer and Pesticide Use in a Central California Agricultural Area: A Case Control Study

OBJECTIVE

To examine environmental factors that influence risk of thyroid cancer.

METHODS

We performed a case-control study utilizing thyroid cancer cases from the California Cancer Registry (1999-2012) and controls sampled in a population-based manner. Study participants were included if they were diagnosed with thyroid cancer, lived in the study area at their time of diagnosis, and were ≥35 years of age. Controls were recruited from the same area and eligible to participate if they were ≥35 years of age and had been living in California for at least 5 years prior to the interview. We examined residential exposure to 29 agricultural use pesticides, known to cause DNA damage in vitro or are known endocrine disruptors. We employed a validated geographic information system-based system to generate exposure estimates for each participant.

RESULTS

Our sample included 2067 cases and 1003 controls. In single pollutant models and within a 20-year exposure period, 10 out of 29 selected pesticides were associated with thyroid cancer, including several of the most applied pesticides in the United States such as paraquat dichloride [odds ratio (OR): 1.46 (95% CI: 1.23, 1.73)], glyphosate [OR: 1.33 (95% CI: 1.12, 1.58)], and oxyfluorfen [OR: 1.21 (95% CI: 1.02, 1.43)]. Risk of thyroid cancer increased proportionately to the total number of pesticides subjects were exposed to 20 years before diagnosis or interview. In all models, paraquat dichloride was associated with thyroid cancer.

CONCLUSIONS

Our study provides first evidence in support of the hypothesis that residential pesticide exposure from agricultural applications is associated with an increased risk of thyroid cancer.

Incidentally discovered papillary thyroid microcarcinoma in patients undergoing thyroid surgery for benign disease

INTRODUCTION

The incidence of thyroid carcinoma has grown significantly over the last few decades. A possible explanation is the increased diagnosis of small thyroid microcarcinoma (TMc). TMc reach a maximum diameter of ≤1 cm, identified during histopathology examination following a thyroidectomy performed for reasons not pertaining to malignancy. This study aims to investigate the prevalence of papillary thyroid microcarcinoma (PTMc) according to the benign pathology that refers patients to surgery and its trend evolution.

METHODS

Retrospective cohort analysis of 1815 patients who underwent total thyroidectomy for non-malignant diseases in the 2005-2020 period.

RESULTS

The mean age of the subjects was 53.5 years, with a higher proportion of women (1481, 82.1%). A total of 167 PTMc (9.3%) were incidentally discovered. A multivariate logistic regression analysis was performed, showing no differences in prevalence according to sex or age in patients with PTMc compared to final benign histology. Multinodular goiter increases the risk of PTMc with an odds ratio of 2.2 (p = 0.001) compared to Hashimoto's thyroiditis and Graves' disease (GD). There is a statistically significant increase in the incidence of PTMc in the group operated in the 2017-2020 vs. 2005-2008 period (p = 0.005).

CONCLUSION

The overall prevalence of PTMc in patients who underwent thyroid surgery for the benign disease was 9.3%. Thyroid nodular hyperplasia was the most frequent benign pathology associated with PTMc compared to Hashimoto's or GD. Gender and age were not correlated with the prevalence of TMc. Over the years, surgical findings of PTMc have grown, particularly in the 2017-2020 period.

The utility of serum anti-thyroglobulin antibody and thyroglobulin in the preoperative differential diagnosis of thyroid follicular neoplasms

PURPOSE

Distinguishing follicular thyroid carcinoma (FTC) from follicular thyroid adenoma (FTA) before surgery is inherently challenging owing to the lack of malignant features on ultrasound, poor sensitivity of fine-needle biopsy, and the absence of definitive markers. We investigated whether thyroglobulin (Tg), anti-thyroglobulin antibody (TgAb), thyroid peroxidase antibodies (TPOAb), and thyroid stimulating hormone (TSH) can help differentiate FTC from FTA.

METHODS

Data pertaining to 319 patients with follicular neoplasms were retrospectively analyzed. We compared the serum markers between patients with confirmed FTC and FTA. We also analyzed the prevalence of FTC in different subgroups of patients based on serum marker levels.

RESULTS

TgAb was a risk factor for FTC. Compared to TgAb ≤11.68 IU/mL group, the odds ratio (OR) for FTC in TgAb 11.69-30.50 IU/mL group and TgAb >30.50 IU/mL group were 2.206 (1.114-4.369, P = 0.023) and 3.247 (1.684-6.260, P < 0.001), respectively. The prevalence of malignancy in TgAb >30.50 IU/mL group was significantly higher than in the TgAb ≤11.68 IU/mL group (32.9 vs. 13.1%, P = 0.001). In patients with TgAb (-) status, Tg was another risk factor for FTC. Compared to Tg ≤38.51 ng/mL group, OR of Tg >434.60 ng/mL group was 3.836 (1.625-9.058, P = 0.002); the prevalence of malignancy in the Tg >434.60 ng/mL group was 47.2% and higher than other groups.

CONCLUSIONS

TgAb and Tg levels may be useful markers for preoperative differential diagnosis of follicular neoplasms. Higher TgAb and Tg levels were associated with greater malignant risk. Thus, we should be cautious of preoperative TgAb and Tg in follicular neoplasms.

Potential Impact of Body Mass Index on the Clinical Outcome of Papillary Thyroid Cancer After High-Dose Radioactive Iodine Therapy

CONTEXT

Obesity has been reported as a potential risk factor for the aggressiveness of papillary thyroid cancer (PTC), but the data gathered so far are conflicting.

OBJECTIVE

The aim of our study was to evaluate the relationship between body mass index (BMI) and aggressiveness of PTC at the diagnosis and clinical outcome.

METHODS

A total of 337 patients who underwent radioactive iodine (RAI) therapy between March 2017 and May 2020 were recruited. Patients were divided into four groups: underweight (BMI<18.5 kg/m²), normal weight (18.5-24.9 kg/m²), overweight (25-29.9 kg/m²), and obese (BMI≥ 30 kg/m²). Treatment and follow-up were defined according to criteria used in the 2015 ATA guidelines.

RESULTS

This study included 337 patients with PTC (71.5% women, median age 45.21 ± 13.04 years). The mean BMI was 24.2 ± 3.1 kg/m². Obese groups had a higher age than the other groups (P = 0.001). Moreover, obese patients had larger tumor sizes and higher T stage, compared to overweight, normal weight, and underweight patients (P = 0.007). After a median follow-up of 32 months, 279 patients (82.7%) had achieved an excellent response (ER) to therapy. The overall ER rates were compared between groups, and they did not differ significantly.

CONCLUSIONS

We demonstrated that BMI may have an additive effect on the aggressiveness of PTC, but did not have an effect on the response to therapy after high-dose RAI therapy.

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.

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.

Pre-existing Thyroiditis Ameliorates Papillary Thyroid Cancer: Insights From a New Mouse Model

Papillary thyroid cancer (PTC) often co-occurs with Hashimoto's thyroiditis, an association that has long been reported in clinical studies yet remains controversial. Some studies, in fact, have suggested a protective effect of thyroiditis while others have not. We generated a mouse model where PTC and thyroiditis develop in a predictable manner, combining the oncogenic drive of the BRAFv600E mutation (inducible by tamoxifen) to the thyroiditis susceptibility of the NOD.H2h4 strain (inducible by iodine). A total of 113 NOD.H2h4_TPO-CRE-ER_BRAFV600E mice (50 followed throughout lifetime and 63 sacrificed at 16 weeks post tamoxifen) were used to determine whether the PTC phenotype differs when thyroiditis precedes or coincides with the onset of PTC. Mice with pre-existing thyroiditis lived longer (median survival of 28.2 weeks post tamoxifen) than those with concomitant (25.6 weeks) or no (24.5 weeks) thyroiditis (P < 0.01 by Laplace regression). PTC developed less frequently (33%) in the pre-existing thyroiditis group than the concomitant (100%) or no (100%) thyroiditis groups (P < 0.001 by chi-squared) and showed less aggressive histopathological features. The intratumoral mononuclear cell infiltration was more prominent in mice with pre-existing thyroiditis (P = 0.002 vs the other groups) and sustained by a significant expansion of effector memory CD8 + T cells and CD19 + B cells. These findings shed light on the controversial PTC-thyroiditis association and emphasize the contribution of intratumoral T and B lymphocytes to the evolution of PTC.

A challenging TSH/GH co-secreting pituitary adenoma with concomitant thyroid cancer; a case report and literature review

BACKGROUND

Thyroid stimulating hormone (TSH) secreting pituitary adenoma (TSHoma) with coexisting thyroid cancer is extremely rare, and proper treatment of both diseases may pose a unique clinical challenge. When TSHoma has plurihormonality, particularly involving the co-secretion of growth hormone (GH), management can be more complicated. Herein, we present a difficult-to-manage case of papillary thyroid cancer with an incurable TSH/GH-secreting pituitary adenoma.

CASE PRESENTATION

A 59-year-old man was referred to our hospital due to memory impairment and inappropriate TSH level. Sella magnetic resonance imaging revealed a huge pituitary mass extending to the suprasellar area. Clinical diagnosis of TSH/GH co-secreting pituitary adenoma was made based on elevated free T4, total T3, serum α-subunit, insulin-like growth factor-1 levels and non-suppressible GH levels after oral glucose loading. Rectal cancer and multifocal papillary thyroid microcarcinoma (PTMC) were diagnosed during initial screening for internal malignancy; lower anterior resection was performed and close observation was planned for PTMC. Long-acting octreotide therapy was commenced, which resulted in a dramatic reduction in TSHoma size and facilitated control of hormonal excess. Total thyroidectomy and radioactive iodine (RAI) therapy were needed during follow up due to the growth of PTMC. After the surgery, the pituitary adenoma represented resistance to somatostatin analogue therapy and the tumor size gradually increased despite the addition of dopamine agonist therapy. Furthermore, TSH suppressive therapy with levothyroxine was impossible and an adequate TSH level for RAI therapy was unmountable. Late debulking pituitary surgery was ineffective, and the patient gradually deteriorated and lost to follow up.

CONCLUSION

We report the first aggravated case of TSH/GH co-secreting pituitary tumor after total thyroidectomy for concomitant multifocal PTMC. Deferring of thyroid surgery until the TSHoma is well controlled may be the optimal therapeutic strategy in patients with TSHoma and coexistent thyroid cancer; ablative thyroid surgery may result in catastrophic pituitary tumor growth.

The Effects of Chronic Lymphocytic Thyroiditis on Clinicopathological Factors In Papillary Thyroid Cancer

INTRODUCTION

This study evaluated the impact of chronic lymphocytic thyroiditis (CLT) on clinicopathological parameters, prognostic outcome and initial treatment responses in patients with papillary thyroid cancer (PTC).

METHODS

A retrospective review was made of 1409 patients with PTC, comprising 443 pathology proven PTC patients with CLT and 447 PTC patients without CLT.

RESULTS

The median follow-up time was 58 (8-380) months and the median age at the time of diagnosis was 43 years. The diagnosis age was significantly lower in patients with CLT (42 vs. 45 years, p:0.001). The preoperative TSH level was found to be significantly higher in CLT patients (1.71 mIU/L vs. 1.28 mIU/L, p<0.001). Multifocality, capsular, lymphovascular and perineural invasion were detected at a higher rate in the group with CLT than in the group without CLT (p:0.015, p:0.024, p:0.004, p:0.039, respectively). No difference was found between the two groups in terms of tumor size, bilaterality, extrathyroidal invasion, lymph node metastasis, disease stage and response to treatment (p>0.05).

CONCLUSION

The results of the present study demonstrated that coexistence of PTC and CLT is very frequent. It was found that patients with PTC and CLT coexistence were diagnosed at an earlier age and the TSH level was higher. Contrary to previous studies, no positive effect of CLT and PTC combination was detected on any clinicopathological factor. In addition, lymphovascular and perineural invasion, which had negative effects on prognosis, was more common in the CLT group.

Association Study of rs2987983 Polymorphism in the Promoter Region of ESR2 Gene and Susceptibility to Nodular Thyroid in Women of Markazi Province, Iran

Background: The risk of thyroid disease has been increased during recent years; more than 200 million people are suffering from various types of thyroid diseases. The rate of thyroid nodules in women is 4 times more than that of men. Epidemiological findings and experimental evidence of thyroid lesions suggest that sex hormones, especially estrogen, may affect this gland and its neoplasms. Objectives: Considering the prevalence of benign and malignant thyroid disease in women, we investigated the association between rs2987983 polymorphism in the estrogen receptor beta gene and nodular thyroid disease. Methods: In this case-control study, 146 patients with thyroid nodules from Amir- Almomenin Hospital in Arak were compared with 151 healthy individuals. The diagnosis was performed by ultrasonography and confirmed by an endocrinologist. After DNA extraction, genotyping was performed with T-ARMS PCR. Finally, statistical analysis was carried out. Results: The frequencies of AA, AG, and GG genotypes in the case group were 48 (32.9%), 83 (56.8%), and 15 (10.3%), respectively. These values in the control group were 64 (42.4%), 64 (42.4%), and 23 (15.2%), respectively. Overall, a statistically significant association (P = 0.042, χ2 = 6.3, df = 2) was observed between rs2987983 polymorphism and thyroid nodules. Conclusions: Considering the significant association between rs2987983 polymorphism and thyroid nodules, it can be suggested that the mentioned polymorphism may be used as a diagnostic biomarker. Because this polymorphism is in the promoter region of the gene, it probably alters gene expression levels.

The Effect of ThyroidߚStimulating Hormone on Stage of Differentiated Thyroid Carcinoma

Introduction

Thyroid cancer is the most common endocrine malignancy, and it has the fastest increase rate in incidence in both sexes, with a yearly increase of 3% over the last decade. Thyroid‐stimulating hormone (TSH) is the main driver for the thyroid gland to produce thyroid hormone. The main purpose of this study was to assess the relationship between serum TSH level and the stage of malignancy in patients with differentiated thyroid cancer.

Methods

This cross‐sectional study was performed on 77 patients with thyroid cancer. The demographic characteristics, TSH level and stage of malignancy were recorded for all patients in the data collection form. The data analysis was conducted by descriptive statistics using SPSS 20.0 software.

Results

The results show a significant relationship (p‐value = .025) between the malignancy stage and serum TSH level. The mean TSH level in patients of stage 3 (5.70 ± 2.03) was significantly higher than patients in stage 2 (2.58 ± 0.52) and stage 1 (2.33 ± 0.28). No significant relationship was observed between the age of patients and serum TSH level. Although the mean serum TSH level in men (3.61 ± 0.98) was higher than in women (2.52 ± 0.25), the difference was not statistically significant.

Conclusions

According to the results of this study, serum TSH level can be considered as a predictor of the stage of differentiated thyroid cancer. Therefore, it can be used to predict the likelihood of cancer and improve the outcome and extent of thyroidectomy in patients with thyroid cancer.

Thyroid‐stimulating hormone (TSH) is the main driver for the thyroid gland to produce thyroid hormone. The main purpose of this study is to assess the relationship between serum TSH level and the stage of malignancy in patients with differentiated thyroid cancer.

The Association of Histologically Proven Chronic Lymphocytic Thyroiditis with Clinicopathological Features, Lymph Node Metastasis, and Recurrence Rates of Differentiated Thyroid Cancer

The influence of chronic lymphocytic thyroiditis (CLT) on clinicopathological features and behavior of differentiated thyroid carcinoma (DTC) is still debated. In the present study, we aimed to evaluate the prognosis of DTC on the presence of CLT. A total of 649 total thyroidectomized patients (379 female, 270 male) with DTC, who had follow-up data for at least 36 months were included. Clinical, histopathological data, preoperative thyroid peroxidase antibody (TPO-ab), thyroglobulin antibody (Tg-ab), thyroid-stimulating hormone (TSH) levels, and presence of recurrent/persistent disease (R/PD) were evaluated retrospectively. Presence of CLT was defined by histopathology. Frequency of CLT was 32% (n = 208) among DTC patients. Mean tumor size (maximal diameter) was smaller in CLT group when compared to non-CLTs (p = 0.006). Capsular invasion, vascular invasion, tumor stage, risk groups, and R/PD were negatively associated with CLT (p < 0.01, p = 0.04, p = 0.03, p = 0.02, p < 0.01, respectively). Extrathyroidal extension was more frequent in non-CLT group when compared CLT (p = 0.052). Preoperative TSH level was positively associated with lymph node metastasis (LNM) and higher in patients with lateral LNM when compared to central LNM (p < 0.01). Central LNM, lateral LNM, stage 4 tumor, and intermediate- and high-risk tumor groups increased the risk of R/PH, 2.5-, 2.9-, 12.7-, 2.3-, and 4.2-fold, respectively. Presence of CLT was independently related with favorable outcomes, as the risk of R/PD was decreased by 0.49-fold. In conclusion, coexistence of CLT was negatively associated with tumor size, capsular invasion, vascular invasion, and tumor stage in DTC. Risk of R/PD was decreased by approximately half in patients with CLT.

Urinary Biomarkers of Phthalates Exposure, Blood Lead Levels, and Risks of Thyroid Nodules

Thyroid nodules (TNs) are becoming increasingly prevalent. However, few studies have reported the effects of phthalates and lead (Pb) on TNs. In this study, we aimed to explore the associations of phthalates and Pb with the risks of TN. We sex-age-matched 220 TNs patients and 220 healthy controls from Zhejiang Shangyu, China. We measured 13 phthalate metabolites in spot urine samples. Blood lead levels (BLLs) were determined by atomic absorption spectrometry. The multivariable logistic regression models were used to assess the associations between urinary phthalate metabolites and BLLs and the risks of TNs. We found BLLs were associated with increased risk of TNs in total population. Female-specific positive associations of mono-2-ethyl-5-carboxypentylphthalate (MECPP), mono-2-ethyl-5-hydroxyhexylphthalate (MEHHP), mono-2-ethyl-5-oxohexylphthalate (MEOHP), mono-2-carboxymethyl-hexyl phthalate (MCMHP), and mono-isononyl phthalate (MiNP) with increased risk of TNs were also observed. Moreover, the positive association between phthalates and TNs was modified by BLLs. At the highest tertile of BLLs, monoethylphthalate (MEP), MECPP, MEHHP, MEOHP, and MiNP were significantly associated with increased risk of TNs. Our results indicated that certain phthalate metabolites and BLLs may contribute to increased risks of TNs.

Malignancy rates in thyroid nodules classified as Bethesda categories III and IV; a subcontinent perspective

BACKGROUND

Bethesda category III and IV thyroid nodules fall in the indeterminate risk of malignancy category. These nodules have been a relatively elusive entity to manage as previous studies have shown a wide variation in malignancy rates in different regions and institutions across the world. However, data from the subcontinent with regards to this is scarce.

AIM AND OBJECTIVE

This study aimed to determine the characteristics and malignancy rates of cytology proven Bethesda Category III and IV thyroid nodules and its association with clinical, histopathological and laboratory variables, in the regional population.

METHOD

A retrospective search was performed on all patients with thyroid nodules who presented to this hospital, from January 2011 to September 2018. Patients who had cytology proven Bethesda category III and IV thyroid nodules that underwent surgery were included in the study.

RESULTS

Malignancy in Bethesda Category III and Bethesda Category IV thyroid nodules was 29.6% and 47.1%, respectively. There was no significant association determined between malignancy rate and various clinical, histopathological, and radiological characteristics.

CONCLUSION

The malignancy rates in Bethesda category III and IV thyroid nodules in this study are significantly higher than that initially suggested by the Bethesda consensus publication but is comparable to international data present.

L-T4 Therapy in Enteric Malabsorptive Disorders

Levothyroxine (L-T4) absorption can be impaired by various causes: a) L-T4 ingestion during breakfast, or with food; b) conditions of reduced gastric acidity; c) intestinal procedures and diseases such as bariatric surgery, lactose intolerance (LI), celiac disease (CD), inflammatory bowel disease; d) drugs that alter L-T4 absorption, increasing the gastric pH, or preventing the dissolution of tablets. The development of new oral formulations, i.e. the liquid preparation and the soft gel capsule, represents the most recent advance regarding L-T4 therapy. Treating hypothyroidism with L-T4 tablets can lead to an improper control of thyroid-stimulating hormone (TSH) in ~10%-15% of patients. The improperly elevated TSH is usually managed by increasing the L-T4 daily dose, and revaluating TSH upon 2-6 months. The increase of the L-T4 dosage may cause iatrogenic hyperthyroidism, especially when the underlying disorders are cured. Liquid L-T4 can be administered in patients unable to swallow capsules or tablets, and this is one of its major benefits. Liquid L-T4 can: 1- overcome food and beverages interference; 2- bypass the malabsorption associated with an increased gastric pH; 3- circumvent the issue of malabsorption in patients who underwent bariatric surgery; 4-maintain TSH values under control better than L-T4 tablets in hypothyroid patients with typical or atypical CD, or in patients with LI. Few clinical studies evaluated soft gel L-T4 with encouraging findings in patients with gastric- or coffee-related malabsorption, or hypothyroid patients without malabsorption. Additional research is necessary to investigate liquid L-T4, or soft gel capsule, in other conditions of altered L-T4 absorption.

Pesticide exposure and incident thyroid cancer among male pesticide applicators in agricultural health study

BACKGROUND

Many pesticides are known to have thyroid-disrupting properties. However, few studies have evaluated the association between specific pesticide ingredients and risk of thyroid cancer. We investigated self-reported pesticide use and incident thyroid cancer in the Agricultural Health Study (AHS), a large cohort of occupationally-exposed male pesticide applicators.

METHODS

The AHS is a prospective cohort of licensed pesticide applicators in Iowa and North Carolina. At enrollment (1993-1997) and follow-up (1999-2005), participants reported use of 50 pesticides. We characterized exposure as ever use (44 pesticides with ≥5 exposed cases) and by cumulative intensity-weighted lifetime days (22 pesticides with ≥10 exposed cases), a metric that accounts for factors that influence exposure. We estimated hazard ratios (HR) and 95% confidence intervals (CI) using Cox regression for incident thyroid (n = 85 cases) cancer among male participants using follow-up through 2014/2015.

RESULTS

Use of the fungicide metalaxyl (HR = 2.03, CI:1.16-3.52) and the organochlorine insecticide lindane (HR = 1.74, CI:1.06-2.84) was associated with increased risk of thyroid cancer. The herbicide chlorimuron-ethyl was inversely associated with risk when we restricted to papillary thyroid cancer, the most common subtype (HR = 0.52, CI:0.28-0.96). High use of the insecticide carbaryl (>median intensity-weighted days) was inversely associated with thyroid cancer (HR = 0.20, CI:0.08-0.53, p_trend = 0.001).

CONCLUSIONS

In this large cohort study, we observed increased risk of thyroid cancer associated with use of metalaxyl and lindane, and an inverse association with carbaryl. More work is needed to understand the potential role of these chemicals in thyroid carcinogenesis.

Development and Internal Validation of a Predictive Model for Individual Cancer Risk Assessment for Thyroid Nodules

OBJECTIVE

The objective of this study was to develop and validate a predictive model for the assessment of the individual risk of malignancy of thyroid nodules based on clinical, ultrasound, and analytic variables.

METHODS

A retrospective case-control study was carried out with 542 patients whose thyroid nodules were analyzed at our endocrinology department between 2013 and 2018 while undergoing treatment for thyroidectomy. Starting with a multivariate logistic regression analysis, which included clinical, analytic, and ultrasound variables, a predictive model for thyroid cancer (TC) risk was devised. This was then subjected to a cross-validation process, using resampling techniques.

RESULTS

In the final model, the independent predictors of the risk of malignancy were: being male, age of the extremes, family history of TC, thyroid-stimulating hormone level >4.7 μU/L, presence of autoimmune thyroiditis, solid consistency, hypoechogenicity, irregular or microlobed borders, nodules that are taller than they are wide, microcalcifications, and suspicious adenopathy. With a cut-off point of 50% probability of thyroid cancer, the predictive model had an area under the receiver operating characteristic curve of 0.925 (95% confidence interval 0.898 to 0.952). Finally, using the 10-fold cross-validation method, the accuracy of the model was found to be 88.46%, with a kappa correlation coefficient of 0.62.

CONCLUSION

A predictive model for the individual risk of malignancy of thyroid nodules was developed and validated using clinical, analytic, and ultrasound variables. An online calculator was developed from this model to be used by clinicians to improve decision-making in patients with thyroid nodules.

An analysis of the correlation between thyroid nodules and metabolic syndrome

OBJECTIVE

The purpose of this study was to explore the prevalence of thyroid nodules (TN) and metabolic syndrome (MS) and to analyze the correlation between TN and the components of MS.

METHODS

A total of 1526 subjects were divided into two groups: a TN group and a non-thyroid nodules (NTN) group. The height, weight, blood pressure, fasting blood glucose level, fasting plasma insulin level, serum lipid profile, uric acid level, serum thyroid-stimulating hormone (TSH) level, free triiodothyronine (FT3) level, and free thyroxine (FT4) level of each patient were measured. Insulin resistance (IR) was estimated by homeostasis model assessment of insulin resistance (HOMA-IR). Fatty liver and TN were detected by color Doppler ultrasonography.

RESULTS

(i) The overall prevalence of TN was 39.5%; it was significantly higher in women than in men (P < 0.01) and progressively increased with age in both sexes. (ii) The overall prevalence of MS was 25.6%; it was significantly higher in men than in women (P < 0.01) and progressively increased with age in both sexes. (iii) FT3 was significantly lower in the TN group than in the NTN group (P < 0.01). (iv) BMI, triglycerides, and HOMA-IR were higher in the TN group than in the NTN group (P < 0.05). (v) The existence of TN was significantly associated with overweight/obesity (OR = 1.03, 95% CI = 1.024-1.089), and with insulin resistance (IR) (OR = 1.98, 95% CI = 1.645-2.368), after adjusting for age and sex.

CONCLUSIONS

The prevalence of thyroid nodules and metabolic syndrome in the Nanchang area increases with age, and overweight/obesity and IR in patients are associated with thyroid nodules.

Causal associations of thyroid function and dysfunction with overall, breast and thyroid cancer: A two-sample Mendelian randomization study

Whether thyroid dysfunction plays a causal role in the development of cancer remains inconclusive. We conducted a two-sample Mendelian randomization study to investigate the associations between genetic predisposition to thyroid dysfunction and 22 site-specific cancers. Single-nucleotide polymorphisms associated with four traits of thyroid function were selected from a genome-wide association meta-analysis with up to 72,167 European-descent individuals. Summary-level data for breast cancer and 21 other cancers were extracted from the Breast Cancer Association Consortium (122,977 breast cancer cases and 105,974 controls) and UK Biobank (367,643 individuals). For breast cancer, a meta-analysis was performed using data from both sources. Genetically predicted thyroid dysfunction was associated with breast cancer, with similar patterns of associations in the Breast Cancer Association Consortium and UK Biobank. The combined odds ratios of breast cancer were 0.94 (0.91-0.98; p = 0.007) per genetically predicted one standard deviation increase in TSH levels, 0.96 (0.91-1.00; p = 0.053) for genetic predisposition to hypothyroidism, 1.04 (1.01-1.07; p = 0.005) for genetic predisposition to hyperthyroidism and 1.07 (1.02-1.12; p = 0.003) per genetically predicted one standard deviation increase in free thyroxine levels. Genetically predicted TSH levels and hypothyroidism were inversely with thyroid cancer; the odds ratios were 0.47 (0.30-0.73; p = 0.001) and 0.70 (0.51-0.98; p = 0.038), respectively. Our study provides evidence of a causal association between thyroid dysfunction and breast cancer (mainly ER-positive tumors) risk. The role of TSH and hypothyroidism for thyroid cancer and the associations between thyroid dysfunction and other cancers need further exploration.

Obesity as a risk factor for thyroid cancer

PURPOSE OF REVIEW

In this review, we evaluate recent findings related to the association between obesity and thyroid cancer.

RECENT FINDINGS

During the last several decades, the prevalence of obesity and thyroid cancer have been increasing in parallel on a global scale. Current evidence suggests that the growing incidence of differentiated thyroid cancer (DTC) is pathogenically linked to the spread of obesity, but the biological mechanisms that may explain this connection have been only partially described. Furthermore, unlike other tumors, data on the impacts of obesity on the aggressiveness of DTC and response to treatment of DTC remain conflicting.

SUMMARY

Emergent knowledge regarding the links between obesity and thyroid cancer suggests a relevant role for obesity as a risk factor for DTC, with no apparent impact on its aggressiveness.

Correlation between thyroid autoantibodies and the risk of thyroid papillary carcinoma

BACKGROUND

To investigate the correlation of thyroglobulin antibody (TgAb) and thyroid peroxidase antibody (TPOAb) with the risk of papillary thyroid carcinoma (PTC).

METHODS

The clinical data of 322 patients with pathologically confirmed thyroid nodules who underwent surgical treatment in Lishui Hospital of Zhejiang University from January 2018 to December 2019 were enrolled in this study. The enrolled patients were divided into a benign nodule group and a PTC group according their pathological results. Comparison was drawn based around the difference of thyroid autoantibody distribution between groups and its correlation with the risk of PTC.

RESULTS

The positive rate of TgAb in the PTC group was significantly higher than that in the benign nodule group (P<0.05). The incidence of PTC was significantly higher in TgAb positive patients in the presence of negative TPOAb (P<0.05). Further regression analysis revealed positive TgAb to be a risk factor of PTC (OR =3.097, P<0.05), while age ≥55 years old (OR =0.188, P<0.05) and nodule diameter ≥10 mm (OR =0.064, P<0.05) reduced the risk of PTC. Simultaneously, positive TgAb was also a risk factor for PTC in females (OR =3.532, P<0.05), but not in males (P>0.05). The risk of PTC in females was not associated with further increase in the titer of TgAb.

CONCLUSIONS

TgAb may be associated with an increased risk of PTC in females, but there is no clear correlation between the risk of PTC and higher antibody titer in these patients.

Effect of thyrotropin suppressive therapy on heart rate variability and QT dispersion in patients with differentiated thyroid cancer

The effects of thyrotropin (TSH) suppressive therapy on autonomic regulation and ventricular repolarization in patients with differentiated thyroid cancer (DTC) have not been elucidated. The aim of present study was to evaluate variation in heart rate variability (HRV) and QT dispersion after TSH suppressive therapy in patients with DTC.Cases, defined as 271 patients with DTC within 1 year of exogenous levothyroxine, and all patients underwent a full history, physical examination, including standard 12 lead electrocardiogram (ECG), and 24 h ambulatory ECG monitoring (Holter) with normal free thyroxine (FT4) and free triiodothyronine (FT3) with levothyroxine. To evaluate effects of TSH suppressive therapy on HRV and QT dispersion, patients were divided into three groups according to different levels of TSH: TSH < 0.1 mIU/L group and 0.1 ≤ TSH < 0.5 mIU/L group were as TSH suppression groups, and 0.5 ≤ TSH < 2.0 mIU/L group was as TSH replacement group.Comparing with 0.5 ≤ TSH < 2.0 mIU/L group, significant changes in both time and frequency domain of HRV and QT dispersion were observed in TSH < 0.1 mIU/L group (P < .001: SDNN, SDANN, HF, LF/HF, QTd, and QTcd; P < .05: rMSSD) and 0.1 ≤ TSH < 0.5 mIU/L group (P < .001: SDNN, HF, LF/HF, QTd, and QTcd), and especially were more pronounced in TSH < 0.1 mIU/L group. Moreover, we found that TSH level was proportional to SDNN (β = 15.829, P < .001), but inversely proportional to LF/HF (β = -0.671, P < .001), QTd (β = -16.674, P < .001) and QTcd (β = -18.314, P < .001) in DTC patients with exogenous levothyroxine.Compared with euthyroid state, patients with suppressed serum TSH have increased sympathetic activity in the presence of diminished vagal tone, ultimately showed sympathovagal imbalance and with an increased inhomogeneity of ventricular recovery times. These findings revealed that TSH suppression therapy had a significant impact on cardiovascular system and had certain guiding role in the treatment and management of patients with DTC.

Higher TSH Is Not Associated With Thyroid Cancer Risk in the Presence of Thyroid Autoimmunity

BACKGROUND

Higher-but-within-normal thyrotropin (thyroid-stimulating hormone, TSH) is associated with higher risk for differentiated thyroid cancer (DTC) in surgical series. Our recent clinical observations suggest that this is not the case in the presence of autoimmune thyroid disease (AITD). We designed the present study to clarify this controversy.

METHODS

We analyzed our prospectively collected database of patients referred for thyroid surgery at 2 tertiary care referral centers in Greece and the United States. We collected data for preoperative TSH, postoperative pathology, and thyroid peroxidase (TPO) antibodies titers. Subjects were subdivided into 2 groups, those with AITD (i.e., lymphocytic thyroiditis) and non-AITD. We excluded subjects with Graves disease, abnormal TSH (< 0.40 or > 4.50 mIU/mL), or recent use of levothyroxine. We compared the serum TSH among different groups using the Mann-Whitney test.

RESULTS

A total of 3973 subjects were screened; 1357 met exclusion criteria. After all exclusions, data from 1731 non-AITD subjects and 329 AITD subjects were included in the analysis. AITD subjects had higher TSH than non-AITD subjects (2.09 vs 1.48; P < 0.0001). TSH values were higher in DTC compared with benign histology only in non-AITD subjects (1.65 vs 1.40; P < 0.0001). Progressively higher TSH was associated with higher incidence of DTC only in non-AITD subjects (P < 0.0001). In AITD subjects, TSH was similar between groups with or without DTC (2.02 vs 2.14; P = 0.21).

CONCLUSIONS

TSH concentrations are not associated with the risk of developing DTC in the presence of thyroid autoimmunity, even though this seems to be the case for all other patients.

The role of metabolic setting in predicting the risk of early tumour relapse of differentiated thyroid cancer (DTC)

BACKGROUND

The role of insulin resistance and adipocytokines in determining the phenotype and recurrence of differentiated thyroid cancer (DTC) is still unknown. In a previous study, we observed an association between metabolic setting, circulating adipocytokines and thyroid cancer phenotype. The aim of this study was to evaluate the clinical follow-up of patients with DTC and the predictive role of metabolic setting on the risk of tumour relapse.

METHODS

Between September 2016 and January 2017, 57 patients were admitted to our institution to undergo total thyroidectomy because of suspected DTC. Thirty patients with post-surgical histological diagnosis of DTC were included in the study. Each subject underwent pre-surgical analysis of anthropometric parameters, thyroid function and autoimmunity, glucose metabolism, insulin resistance (HOMA-IR) and levels of unacylated and acylated ghrelin, obestatin, leptin and adiponectin. Tumour recurrence at 1 and 3 years from diagnosis was assessed.

RESULTS

Most patients were females (21F, 9M) with a median age at diagnosis of 50.0 (41.0-58.8). At baseline, overweight was found in 7 patients and obesity in 6 cases. Insulin resistance was detected in 14 patients. Overall, 17 patients (56.7%) underwent radioiodine treatment after surgery. During the follow-up, we observed a persistent biochemical disease in one patient whereas tumour relapse was found in six patients at 1 year from diagnosis (lymph node metastases) and in one patient at 3 years from diagnosis (lung metastases). Independently from age, sex, stage of disease and the presence of lymph node metastasis at diagnosis, higher BMI, leptin and insulin levels as well as HOMA-IR were associated with a higher risk of tumour relapse (p < 0.05 for all).

CONCLUSIONS

Our results highlight a possible role for BMI, leptin and insulin resistance as predictors of early DTC relapse.

Is Less More? A Microsimulation Model Comparing Cost-effectiveness of the Revised American Thyroid Association's 2015 to 2009 Guidelines for the Management of Patients With Thyroid Nodules and Differentiated Thyroid Cancer

OBJECTIVE

To assess relative clinical and economic performance of the revised American Thyroid Association (ATA) thyroid cancer guidelines compared to current standard of care.

BACKGROUND

Diagnosis of thyroid cancer in the United States has tripled whereas mortality has only marginally increased. Most patients present with small papillary carcinomas and have historically received at least a total thyroidectomy as a treatment. In 2015, the ATA released the revised guidelines recommending an option for active surveillance (AS) of small papillary thyroid carcinoma and thyroid lobectomy for larger unifocal tumors.

METHODS

We created a Markov microsimulation model to evaluate the performance of the ATA's 2015 guidelines compared to the ATA's 2009 guidelines. We modeled a cohort of simulated patients with demographic and thyroid nodule characteristics representative of those presenting clinically in the United States. Outcome measures include life expectancy, quality-adjusted life years, costs, and frequency of surgical adverse events.

RESULTS

In our base case analysis, the ATA 2015 strategy dominates the ATA 2009 strategy. The ATA 2015 strategy delivers greater discounted average quality-adjusted life years (13.09 vs 12.43) at a lower discounted average cost ($14,752 vs $20,126). Deaths due to thyroid cancer under the 2015 strategy are higher than the 2009 strategy but this is offset by a reduction in surgical deaths, leading to greater average life expectancy under the ATA 2015 strategy. The optimal strategy is sensitive to patients who experience a greater decrement in quality of life while undergoing AS.

CONCLUSIONS

The ATA 2015 Guidelines represent a cost-effective strategy regarding AS and extent of surgery.

Identification and validation of m6A RNA methylation regulators with clinical prognostic value in Papillary thyroid cancer

Background

Papillary thyroid cancer (PTC) is a type of malignant tumor with excellent prognosis, accounting for more than 80% of thyroid cancer. Recently, numerous studies illustrated the importance of N⁶-methyladenosine (m⁶A) RNA modification to tumorigenesis, but it has never been reported in PTC.

Methods

We downloaded data from The Cancer Genome Atlas (TCGA) and analyzed RNA expression, single nucleotide polymorphisms (SNPs) and copy number variations (CNVs) of 19 m⁶A RNA methylation regulators in PTC. Then we used nonnegative matrix factorization (NMF) to cluster patients into two m⁶A subtypes and compared them in overall survival (OS) and disease-free survival (DFS). The Weighted correlation network analysis (WGCNA) and univariate Cox proportional hazard model (CoxPH) were used to select genes for the construction of a m⁶A-related signature. The accuracy and prognostic value of this signature were validated by using receiver operating characteristic (ROC) curves, K-M (Kaplan–Meier) survival analysis, univariant and multivariant analyses.

Results

CNVs and differential expression of m⁶A regulators were observed in PTC patients. Especially IGF2BP2 (Insulin-like growth factor 2 mRNA binding protein 2), which was most significantly overexpressed in tumor tissue. We chose 4 genes in the m⁶A-related module from WGCNA: IGF2BP2, STT3A, MTHFD1 and GSTM4, and used them to construct a m⁶A-related signature. The prognostic value of this signature was validated, and risk scores provided by the signature was the independent prognostic factor for PTC. A nomogram was also provided for clinical usage.

Conclusions

We performed a comprehensive evaluation of the m⁶A RNA modification landscape of PTC and explored its underlying mechanisms. Our m⁶A-related signature was of great significance in predicting the DFS of patients with PTC. And IGF2BP2 was a gene worthy for further analysis as its strong correlation with DFS and clinical phenotypes of PTC.

Cold-hearted: A case for cold stress in cancer risk

A negative correlation exists between environmental temperature and cancer risk based on both epidemiological and statistical analyses. Previously, cold stress was reported to be an effective cause of tumorigenesis. Several studies have demonstrated that cold temperature serves as a potential risk factor in cancer development. Most recently, a link was demonstrated between the effects of extreme cold climate on cancer incidence, pinpointing its impact on tumour suppressor genes by causing mutation. The underlying mechanism behind cold stress and its association with tumorigenesis is not well understood. Hence, this review intends to shed light on the role of associated factors, genetic and/or non-genetic, which are modulated by cold temperature, and eventually influence tumorigenic potential. While scrutinizing the effect of cold exposure on the body, the expression of certain genes, e.g. uncoupled proteins and heat-shock proteins, were elevated. Biological chemicals such as norepinephrine, thyroxine, and cholesterol were also elevated. Brown adipose tissue, which plays an essential role in thermogenesis, displayed enhanced activity upon cold exposure. Adaptive measures are utilized by the body to tolerate the cold, and in doing so, invites both epigenetic and genetic changes. Unknowingly, these adaptive strategies give rise to a lethal outcome i.e., genesis of cancer. Concisely, this review attempts to draw a link between cold stress, genetic and epigenetic changes, and tumorigenesis and aspires to ascertain the mechanism behind cold temperature-mediated cancer risk.

Regression of Papillary Thyroid Cancer during Nivolumab for Renal Cell Cancer

Immune checkpoint inhibitors have been recently approved for cancer treatment. Nivolumab is a monoclonal antibody specific for programmed cell death-1 (PD-1) that modulates T-cell response. It was initially used for the treatment of malignant melanoma and then approved in other cancers, such as non-small cell lung cancer and clear cell renal cell carcinoma (ccRCC). So far, the activity of nivolumab in patients with thyroid malignancies has been reported in a single case of anaplastic thyroid cancer. Here, we report the case of a patient with ccRCC who developed a papillary thyroid carcinoma (PTC) under first-line sunitinib treatment. During nivolumab, the second-line treatment for ccRCC, we unexpectedly observed a complete regression of PTC.

Potential Impact of BMI on the Aggressiveness of Presentation and Clinical Outcome of Differentiated Thyroid Cancer

BACKGROUND

Obesity is a risk factor for several cancers, including differentiated thyroid cancer (DTC). Moreover, it has also been investigated as a potential risk factor for aggressiveness of DTC, but the data gathered so far are conflicting. The aim of our study was to evaluate the relationship between body mass index (BMI), aggressiveness of DTC at diagnosis, and clinical outcome.

METHODS

We evaluated 1058 consecutive DTC patients treated with total thyroidectomy and enrolled at the time of first radioactive iodine (131I) treatment. Patients were divided into 4 groups based on their BMI: underweight (< 18.5 kg/m2), normal weight (18.5-24.9 kg/m2), overweight (25-29.9 kg/m2), and obese (≥ 30 kg/m2). Histological aggressiveness of DTC at the time of diagnosis and clinical outcome according to 2015 American Thyroid Association (ATA) guidelines were evaluated.

RESULTS

No differences in histological features, ATA risk of recurrence, activity of 131I administered and prevalence of 131I avid metastatic disease after first131I treatment, have been demonstrated among the groups. Furthermore, at the end of follow up (median = 5.7 years), no differences were evident in the number of further treatments performed as well as in the clinical response.

CONCLUSIONS

In our study group of Caucasian subjects, we could not demonstrate any association between BMI and aggressiveness of DTC, neither at the time of diagnosis nor during follow-up. These data indicate that postsurgical assessment and therapeutic attitude for treatment and follow-up of DTC should be based on the class of risk applied to the general population, with no concern for BMI.

Thyroid nodules: diagnostic evaluation based on thyroid cancer risk assessment

Thyroid nodules are extremely common and can be detected by sensitive imaging in more than 60% of the general population. They are often identified in patients without symptoms who are undergoing evaluation for other medical complaints. Indiscriminate evaluation of thyroid nodules with thyroid biopsy could cause a harmful epidemic of diagnoses of thyroid cancer, but inadequate selection of thyroid nodules for biopsy can lead to missed diagnoses of clinically relevant thyroid cancer. Recent clinical guidelines advocate a more conservative approach in the evaluation of thyroid nodules based on risk assessment for thyroid cancer, as determined by clinical and ultrasound features to guide the need for biopsy. Moreover, newer evidence suggests that for patients with indeterminate thyroid biopsy results, a combined assessment including the initial ultrasound risk stratification or other ancillary testing (molecular markers, second opinion on thyroid cytology) can further clarify the risk of thyroid cancer and the management strategies. This review summarizes the clinical importance of adequate evaluation of thyroid nodules, focuses on the clinical evidence for diagnostic tests that can clarify the risk of thyroid cancer, and highlights the importance of considering the patient's values and preferences when deciding on management strategies in the setting of uncertainty about the risk of thyroid cancer.

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.

Attributable risk fraction of four lifestyle risk factors of thyroid cancer: a meta-analysis

Background

Lifestyle risk factors such as obesity, overweight, smoking and radiation exposure related to thyroid cancer. This study estimated the amount of excess risk that attributed to risk factors.

Methods

Major electronic databases were searched until February 2016. Epidemiological studies addressing the association between lifestyle risk factors and thyroid cancer were enrolled. The results were expressed as ARF with 95% confidence intervals (CIs) using a random-effects-model.

Results

We identified a total of 13 321 references and included 17 studies. The excess risk of thyroid cancer attributable to radiation exposure was 14% (95% CI: 5%, 23%; eight studies, I2 = 88.7%), to obesity was 13% (95% CI: 5%, 21%; four studies, I2 = 68.7%), to overweight was 10% (95% CI: 2%, 17%; four studies, I2 = 4.1%) and to smoking was -13% (95% CI: -33%, 6%; five studies, I2 = 30.6%). So obesity, overweight and radiation exposure are significantly associated with increased thyroid cancer risk and smoking has a protective effect on thyroid cancer but not significant.

Conclusion

A significant amount of the incidence of thyroid cancer is attributable to lifestyle risk factors. Since these factors are entirely preventable, so it is necessary to reduce factors that are associated with increased thyroid cancer risk and proper education to the community. Thus weight loss and protection against radiation can effectively reduce the incidence rate of thyroid cancer but smoking can have a protective effect.

Thyroid Cancer Incidence Rates in North Dakota are Associated with Land and Water Use

Objective: The increasing rate of thyroid cancer diagnoses in the U.S. reflects the increasing use of ultrasonography and of specialist medical care. North Dakota is a rural state with limited access to specialist care, yet its incidence of thyroid cancer is significantly greater than that of the U.S. overall. We sought to identify factors responsible for the high incidence of thyroid cancer in North Dakota. Methods: We examined county-specific incidence rates for thyroid cancer in North Dakota in relation to demographic and geographic factors, including median household income, percent of land fertilized, cattle density per capita, and source of drinking water (city or well water), using structural equation modeling. We included county level data on residential radon levels and estimates of radioactive iodine in milk following nuclear weapons testing in the 1950s. Results: Thyroid cancer incidence rates were significantly associated with median income (p < 0.05); percent of land fertilized (p < 0.05); the use of city water (p < 0.01), and cattle density per capita (p < 0.001). Conclusions: The risk of thyroid cancer in North Dakota is positively associated with income and with factors related to land and water use. Our finding that thyroid cancer incidence rates are associated with the use of city water was unexpected and merits examination in other locations with a mix of city and well water use.

Mouse Model of Thyroid Cancer Progression and Dedifferentiation Driven by STRN-ALK Expression and Loss of p53: Evidence for the Existence of Two Types of Poorly Differentiated Carcinoma

Background: Thyroid tumor progression from well-differentiated cancer to poorly differentiated thyroid carcinoma (PDTC) and anaplastic thyroid carcinoma (ATC) involves step-wise dedifferentiation associated with loss of iodine avidity and poor outcomes. ALK fusions, typically STRN-ALK, are found with higher incidence in human PDTC compared with well-differentiated cancer and, as previously shown, can drive the development of murine PDTC. The aim of this study was to evaluate thyroid cancer initiation and progression in mice with concomitant expression of STRN-ALK and inactivation of the tumor suppressor p53 (Trp53) in thyroid follicular cells. Methods: Transgenic mice with thyroid-specific expression of STRN-ALK and biallelic p53 loss were generated and aged on a regular diet or with methimazole and sodium perchlorate goitrogen treatment. Development and progression of thyroid tumors were monitored by using ultrasound imaging, followed by detailed histological and immunohistochemical evaluation. Gene expression analysis was performed on selected tumor samples by using RNA-Seq and quantitative RT-PCR. Results: In mice treated with goitrogen, the first thyroid cancers appeared at 6 months of age, reaching 86% penetrance by the age of 12 months, while a similar rate (71%) of tumor occurrence in mice on regular diet was observed by 18 months of age. Histological examination revealed well-differentiated papillary thyroid carcinomas (PTC) (n = 26), PDTC (n = 21), and ATC (n = 8) that frequently coexisted in the same thyroid gland. The tumors were frequently lethal and associated with the development of lung metastasis in 24% of cases. Histological and immunohistochemical characteristics of these cancers recapitulated tumors seen in humans. Detailed analysis of PDTC revealed two tumor types with distinct cell morphology and immunohistochemical characteristics, designated as PDTC type 1 (PDTC1) and type 2 (PDTC2). Gene expression analysis showed that PDTC1 tumors retained higher expression of thyroid differentiation genes including Tg and Slc5a5 (Nis) as compared with PDTC2 tumors. Conclusions: In this study, we generated a new mouse model of multistep thyroid cancer dedifferentiation with evidence of progression from PTC to PDTC and ATC. Further, PDTC in these mice showed two distinct histologic appearances correlated with levels of expression of thyroid differentiation and iodine metabolism genes, suggesting a possibility of existence of two PDTC types with different functional characteristics and potential implication for therapeutic approaches to these tumors.