Signal Pathway of Estrogen and Estrogen Receptor in the Development of Thyroid Cancer

The challenge of survivors of gynecological carcinomas: a retrospective study on occurrence of second tumors

OBJECTIVE

To clarify the epidemiologic characteristics and risk of other tumors in survivors of gynecological tumors.

MATERIALS AND METHODS

This is a retrospective study based on the Surveillance, Epidemiology, and End Results database (SEER).

RESULTS

The morbidity of other malignant tumors in patients with gynecological cancer was 8.07%. The most common subsequent tumors are breast, lung, colorectal, thyroid, and bladder cancers. Taking the incidence rate of the general population as reference, the second tumor with the highest relative risk in patients with cervical cancer is vulvar cancer. Bladder cancer is the second tumor with the highest relative risk value both in patients with corpus and ovarian cancer. The median period from the diagnosis of the initial tumor to the diagnosis of the second tumor was 5 years. Most patients with other tumors following gynecological cancer showed worse prognosis than patients with gynecological tumors only. However, thyroid cancer following ovarian cancer is a protective factor in survival.

CONCLUSION

Patients with gynecological tumors have a significantly higher risk of malignant tumors in other systems compared to ordinary population. It is necessary to be vigilant against subsequent high-risk tumors and tumors with poor prognosis within 5 years of initial diagnosis.

Thyroid cancer trends in China and its comparative analysis with G20 countries: Projections for 2020-2040

Background

Thyroid cancer, a leading type of endocrine cancer, accounts for 3-4% of all cancer diagnoses. This study aims to analyse and compare thyroid cancer patterns in China and the Group twenty (G20) countries, and predict these trend for the upcoming two decades.

Methods

This observational longitudinal study utilised data from the Global Burden of Disease (GBD) study 2019. We used metrics including incidence, mortality, mortality-incidence ratio (MIR), age-standardised rate (ASR) and average annual percent change (AAPC) to examine thyroid cancer trends. Joinpoint regression analysis was used to identify periods manifesting notable changes. The association between sociodemographic index (SDI) and AAPC were investigated. The autoregressive integrated moving average (ARIMA) model was used to predict thyroid cancer trends from 2020 to 2040.

Results

From 1990 to 2019, thyroid cancer incidence cases in China increased by 289.6%, with a higher AAPC of age-standardised incidence rate (ASIR) in men. Contrastingly, the G20 demonstrated a smaller increase, particularly among women over 50. Despite the overall age-standardised mortality rate (ASMR) was higher in the G20, the increase in mortality was less pronounced than in China. Age-standardised incidence rate increased across all age groups and genders, with a notable rise among men aged 15-49. ASMR decreased in specific age groups and genders, especially among women. Conversely, the ASMR significantly increased in group aged over 70. The MIR exhibited a declining trend, but this decrease was less noticeable in men and the group aged over 70. Joinpoint analysis pinpointed significant shifts in overall ASIR and ASMR, with the most pronounced increase in ASIR during 2003-2011 in China and 2003-2010 in the G20. Predictions suggested a continual ASIR uptrend, especially in the 50-69 age group, coupled with a predicted ASMR downturn among the elderly by 2040. Moreover, the proportion of thyroid cancer deaths attributable to high body mass index (BMI) escalated, with significant increase in Saudi Arabia and a rise to 7.4% in China in 2019.

Conclusions

Thyroid cancer cases in incidence and mortality are escalating in both China and the G20. The increasing trend may be attributed to factors beyond overdiagnosis, including environmental and genetic factors. These findings emphasise the necessity for augmenting prevention, control, and treatment strategies. They also highlight the significance of international collaboration in addressing the global challenge posed by thyroid cancer.

Serum sex hormones correlate with pathological features of papillary thyroid cancer

PURPOSE

Sex hormones are thought to be responsible for the unique gender differences in papillary thyroid cancer(PTC). Most previous studies on these have focused on the expression of estrogen receptors, or have been limited to animal studies. The aim of our study was to explore the relationship between serum sex hormones and the pathological features of PTC in the clinical setting, as further evidence of the role of sex hormones in PTC.

METHODS

Retrospective data analysis of patients who underwent thyroid surgery at the Department of Thyroid Surgery, Nanjing Drum Tower Hospital from January 2022 to September 2022 Correlation between serum sex hormone and pathological features was analyzed in male patients and in menopausal female patients. Serum sex hormones include luteinizing hormone(LH), follicle stimulating hormone(FSH), estradiol(E2), total testosterone(TT), progesterone(P), and prolactin(PRL). Tumor pathological characteristics include the number and size of tumor, presence of extrathyroidal extension(ETE), presence of lymph node metastasis(LNM).

RESULTS

Preoperative serum E2 in male patients was positively correlated with tumor size in PTC, LH was negatively correlated with LNM, while TT and P were negatively correlated with ETE. Similar findings were not observed in menopausal female patients.

CONCLUSION

We observed that serum sex hormones correlate with the pathological features of PTC in male patients, for the first time in a clinical study. High serum estrogens may be a risk factor for PTC, while androgens are the opposite. This somewhat corroborates previous research and provides new variables for future PTC prediction models.

MIWE: detecting the critical states of complex biological systems by the mutual information weighted entropy

Complex biological systems often undergo sudden qualitative changes during their dynamic evolution. These critical transitions are typically characterized by a catastrophic progression of the system. Identifying the critical point is critical to uncovering the underlying mechanisms of complex biological systems. However, the system may exhibit minimal changes in its state until the critical point is reached, and in the face of high throughput and strong noise data, traditional biomarkers may not be effective in distinguishing the critical state. In this study, we propose a novel approach, mutual information weighted entropy (MIWE), which uses mutual information between genes to build networks and identifies critical states by quantifying molecular dynamic differences at each stage through weighted differential entropy. The method is applied to one numerical simulation dataset and four real datasets, including bulk and single-cell expression datasets. The critical states of the system can be recognized and the robustness of MIWE method is verified by numerical simulation under the influence of different noises. Moreover, we identify two key transcription factors (TFs), CREB1 and CREB3, that regulate downstream signaling genes to coordinate cell fate commitment. The dark genes in the single-cell expression datasets are mined to reveal the potential pathway regulation mechanism.

Coexistence of Hashimoto's Thyroiditis in Differentiated Thyroid Cancer: Post-Operative Monitoring of Anti-Thyroglobulin Antibodies and Assessment of Treatment Response

INTRODUCTION

Differentiated thyroid carcinoma (DTC) is frequently found in conjunction with autoimmune thyroid disorders, particularly Hashimoto's thyroiditis (HT). This study investigates the impact of coexisting HT on the persistence of an indeterminate response to therapy due to positive anti-thyroglobulin antibodies (AbTg), measured via competitive immunoassay, in a consecutive patient series from Calabria, Southern Italy.

METHODS

This retrospective longitudinal study analyzed 259 consecutive DTC patients managed at the Endocrinology Unit of Renato Dulbecco Hospital (Catanzaro, Italy) up to 2023. Patients with medullary and undifferentiated thyroid carcinoma, partial thyroidectomy, less than six months of post-operative monitoring, or missing clinical data were excluded. Demographic information, histological findings, initial tumor stage, and ATA risk category were collected. The response to therapy was assessed based on ATA guidelines.

RESULTS

Among the 259 patients, 29% had coexisting HT. Patients with HT exhibited distinct characteristics: a higher proportion of females (87.0% vs. 74.7%), a shorter post-operative monitoring duration (median 3 vs. 5 years), and a higher prevalence of papillary thyroid carcinoma (PTC) (97.4% vs. 86.3%). The tumor size, lymph node involvement, and distant metastasis were similar between the groups, with patients without HT having a higher incidence of extrathyroidal tumor extension. However, the initial TNM stage and ATA risk category did not differ significantly. At the six-month follow-up, HT patients showed a higher rate of indeterminate responses, primarily due to positive AbTg. After 12 months, the response categories aligned, with decreasing AbTg levels in the HT group. After 24 months, most patients with long-term follow-up demonstrated an excellent response to DTC therapy, irrespective of HT coexistence.

CONCLUSIONS

While HT does not worsen DTC prognosis, it may result in indeterminate responses. AbTg measurements in the peri-operative period should be encouraged to facilitate post-operative monitoring, emphasizing the importance of using standardized assays. Further research in larger populations with extended follow-up is needed to comprehensively understand the HT-DTC relationship.

Unbalanced bidirectional causal association between thyroid cancer and ER-positive breast cancer: should we recommend screening for thyroid cancer in breast cancer patients?

BACKGROUND

The association between breast cancer (BC) and thyroid cancer (TC) has been studied in several epidemiological studies. However, the underlying causal relationship between them is not yet clear.

METHODS

The data from the latest large-sample genome-wide association studies (GWAS) of BC and TC were searched in the public GWAS database. The BC GWAS data included estrogen receptor (ER)-positive and negative subgroups. Two-way two-sample Mendelian Randomization (MR) was used to explore the potential causal relationship between BC and TC. Inverse variance weighting (IVW) and the MR-Egger method were used to combine the estimation of each single nucleotide variation (previous single nucleotide polymorphism). BC was taken as the result, and the effect of TC exposure was analyzed. Then, the effect of BC exposure on the result of TC was analyzed.

RESULTS

Both IVW and MR-Egger results indicated that gene-driven thyroid cancer does not cause estrogen receptor-positive breast cancer and is a protective factor (β = -1.203, SE = 4.663*10-4, P = 0.010). However, gene-driven estrogen receptor-positive breast cancer can lead to the development of thyroid cancer (β = 0.516, SE = 0.220, P = 0.019).

CONCLUSION

From the perspective of gene drive, people with TC are less likely to have ER-positive BC. In contrast, people with ER-positive BC are more likely to have TC. Therefore, it is recommended that patients with BC be screened regularly for TC.

DNA Methylation Status of HYAL1 in Malignant and Benign Thyroid Nodules

Differentiation between benign and malignant thyroid nodules has been a challenge in clinical practice. Exploring a novel biomarker to determine the malignancy of thyroid nodules has important implications. We semi-quantitatively determined the DNA methylation levels of four CpG sites located at the gene body of HYAL1 in formalin-fixed paraffin-embedded (FFPE) tissue samples from 190 early-stage papillary thyroid cancer (PTC) cases and 190 age- and gender-matched subjects with benign thyroid nodule (BTN). HYAL1 expression was evaluated by immunohistochemical (IHC) staining in another cohort of 55 PTC and 55 matched BTN cases. Covariates-adjusted odds ratios (ORs) for 10% increased methylation were calculated by binary logistic regression. A 165 bp amplicon covering four CpG sites at the second exon of HYAL1 gene was designed. After adjusted for all covariates, higher methylation level of HYAL1_CpG_3,4 in the FFPE tissue was associated with PTC (OR per 10% increased methylation=1.53, p=0.025), even with stage І PTC (OR per 10% increased methylation=1.58, p=0.021). Hypermethylation of HYAL1_CpG_3,4 had a significant association with early-stage PTC in the females (OR per 10% increased methylation=1.60, p=0.028) rather than in the males. Besides, we found the higher expression of HYAL1 protein in PTC than that in BTN patients (IHC score: 2.3 vs. 0.5, p=1.00E-06). Our study suggested altered methylation and expression of HYAL1 could be a novel and potential biomarker in distinguishing malignant and benign thyroid nodules.

Geographic variation in the association between Hashimoto's thyroiditis and Papillary thyroid carcinoma, a meta-analysis

PURPOSE

The association between papillary thyroid cancer (PTC) and Hashimoto's thyroiditis (HT) remains a matter of debate. Several genetic and environmental factors have been found to influence this association. Because of the variation in these factors among different populations, we conducted a country- and region-based meta-analysis to examine whether the geographic area influences this association.

METHODS

We searched PubMed and Web of Science databases for original articles that investigated the association between HT and PTC from February 1955 to February 28, 2023. The included studies were stratified according to their country and region of origin. Various subgroup analyses were conducted. The primary outcome was the pooled relative risk (RR) and its 95% confidence interval (CI) for each region and country.

RESULTS

Forty-six studies including a total of 93,970 participants met our inclusion criteria. They originated from 16 countries distributed in five regions. Significant variation was found among countries but not among regions. Upon analysis of all 46 included studies, countries were classified based on their RR and its 95% CI. Excluding countries with pooled sample sizes <500, Sri Lanka (RR 4.23, 95% CI 2.91-6.14), Poland (RR 3.16, 95% CI 2.79-3.57) and Japan (2.68, 2.14-3.36) showed the strongest association between HT and PTC while Greece (RR 1.06, 95% CI 1.00-1.13), Spain (RR 0.70, 95% CI 0.23-2.11), and Jordan (0.62, 0.32-1.32) showed no significant association.

CONCLUSION

Our findings revealed a variation in the association between HT and PTC among countries but not among regions. The country-to-country variation could be due to certain genetic and/or environmental factors subject to geographic variation that influence this association. These findings may help guide health policies aiming to mitigate the risk of PTC in the HT population by helping identify high-risk and low-risk countries.

Advances in the molecular mechanism and targeted therapy of radioactive-iodine refractory differentiated thyroid cancer

Most patients with differentiated thyroid cancer have a good prognosis after radioactive iodine-131 treatment, but there are still a small number of patients who are not sensitive to radioiodine treatment and may subsequently show disease progression. Therefore, radioactive-iodine refractory differentiated thyroid cancer treated with radioiodine usually shows reduced radioiodine uptake. Thus, when sodium iodine symporter expression, basolateral membrane localization and recycling degradation are abnormal, radioactive-iodine refractory differentiated thyroid cancer may occur. In recent years, with the deepening of research into the pathogenesis of this disease, an increasing number of molecules have become or are expected to become therapeutic targets. The application of corresponding inhibitors or combined treatment regimens for different molecular targets may be effective for patients with advanced radioactive-iodine refractory differentiated thyroid cancer. Currently, some targeted drugs that can improve the progression-free survival of patients with radioactive-iodine refractory differentiated thyroid cancer, such as sorafenib and lenvatinib, have been approved by the FDA for the treatment of radioactive-iodine refractory differentiated thyroid cancer. However, due to the adverse reactions and drug resistance caused by some targeted drugs, their application is limited. In response to targeted drug resistance and high rates of adverse reactions, research into new treatment combinations is being carried out; in addition to kinase inhibitor therapy, gene therapy and rutin-assisted iodine-131 therapy for radioactive-iodine refractory thyroid cancer have also made some progress. Thus, this article mainly focuses on sodium iodide symporter changes leading to the main molecular mechanisms in radioactive-iodine refractory differentiated thyroid cancer, some targeted drug resistance mechanisms and promising new treatments.

Women consuming oral contraceptives containing cyproterone acetate and ethinylestradiol show a higher risk of thyroid cancer than nonusers

This study explored whether the risk of thyroid cancer in Asian women is associated with consumption of oral contraceptives (Diane-35). We conducted a population-based, retrospective cohort study using the Taiwan National Health Insurance Research Database. From the database, 9865 women aged 18 to 65 years who were prescribed Diane-35 between 2000 and 2012 were included in the Diane-35 group, and 39,460 women who were not prescribed Diane-35 were included in the comparison group and were frequency-matched by age and index year. Both groups were followed until 2013 to calculate the incidence of thyroid cancer. Hazard ratios (HR) and 95% confidence intervals (CI) were estimated using Cox proportional hazard model. The median (standard deviation) follow-up duration was 7.08 (3.63) and 7.04 (3.64) years in the Diane-35 and the comparison group, respectively. The incidence of thyroid cancer was 1.80-fold higher in the Diane-35 group than in the comparison group (2.72 vs 1.51 per 10,000 person-years). The cumulative incidence of thyroid cancer was significantly higher in the Diane-35 group than in the comparison group (log-rank test, P = .03). An elevated hazard ratio of thyroid cancer was observed in the Diane-35 group than in the comparison group (HR: 1.91, 95% CI: 1.10-3.30). In subgroup analysis, patients aged 30 to 39 years showed a higher hazard ratio of developing thyroid cancer after consuming Diane-35 than those in the comparison group (HR: 5.58, 95% CI: 1.84-16.91). The study provides evidence that women aged 30 to 39 years consuming Diane-35 are at increased risk of thyroid cancer. Nevertheless, a larger population with a longer follow-up may be necessary to confirm causality.

Health-Related Quality of Life After Thyroid Cancer Surgery: A Single-Center, Cross-Sectional Study in Southern Vietnam

Background Thyroid cancer is the most common malignant disease in the endocrine glands. Symptoms of the disease affect the functions of organs in the body. Although thyroid cancer is often considered a "good cancer" because it progresses slowly, the likelihood of successful treatment is quite high; what is special is that the effect on the quality of life (QoL) is on par with more severe types of cancer. Currently, studies on QoL assessment in thyroid cancer patients are quite limited in southern Vietnam. The present study investigated the potential risk factors of deterioration in QoL scores in thyroid cancer patients after thyroidectomy. Methodology A descriptive, cross-sectional study was performed on a total of 162 patients who were diagnosed with thyroid cancer and underwent thyroidectomy at the University Medical Center Ho Chi Minh City, Vietnam, from February to May 2023. Data were collected through face-to-face interviews with patients and from medical records. The European Organization for Research and Treatment of Cancer Quality of Life Questionnaire Core 30 was used to assess the QoL one month after thyroidectomy. Multivariable logistic regression was used to identify factors related to QoL with statistical significance set at p-value <0.05. Results The mean overall QoL in thyroid cancer survivors was 84.4 ± 10.00 (on a scale of 0-100, where 100 was the best). The results of multivariate logistic regression analysis showed that the factors related to QoL after thyroidectomy were surgery type (p < 0.001), having a comorbidity (p = 0.029), economic status (p = 0.026), and hormone disorder (p = 0.009). Conclusions Our study indicated that surgery type, having a comorbidity, economic status, and hormone disorders were independent risk factors for decreased QoL one month after thyroidectomy. It is necessary to thoroughly assess the QoL before and after surgery in thyroid cancer patients. Longer follow-up QoL studies should be performed with larger sample sizes for more accurate results.

The Tumor Microenvironment and the Estrogen Loop in Thyroid Cancer

Thyroid cancer (TC) cells employ multiple signaling pathways, such as PI3K/AKT/mTOR and RAS/Raf/MAPK, fostering cell proliferation, survival and metastasis. Through a complex interplay with immune cells, inflammatory mediators and stroma, TC cells support an immunosuppressive, inflamed, pro-carcinogenic TME. Moreover, the participation of estrogens in TC pathogenesis has previously been hypothesized, in view of the higher TC incidence observed among females. In this respect, the interactions between estrogens and the TME in TC could represent a relevant, unexplored area of research. We thereby collectively reviewed the available evidence concerning the potential carcinogenic role of estrogens in TC, specifically focusing on their crosstalk with the TME.

Peripubertal soy isoflavone consumption leads to subclinical hypothyroidism in male Wistar rats

Exposure to endocrine-disrupting chemicals during critical windows of development may lead to functional abnormalities in adulthood. Isoflavones are a flavonoid group of phytoestrogens that are recognized by their estrogenic activity and are highly abundant in soybean. Since the thyroid gland presents estrogen receptors and infants, toddlers and teenagers may consume isoflavones from soy-based infant formula and beverages as alternatives to animal milk, we propose to investigate the potential effects of relevant concentrations of soy isoflavones in the regulation of the hypothalamic-pituitary (HP) thyroid axis using peripubertal male rats as an experimental model. Thirty-two 23-day-old male rats were exposed to 0.5, 5, or 50 mg of soy isoflavones/kg from weaning to 60 days of age, when they were euthanized, and the tissues were collected to evaluate the mRNA expression of genes involved in the regulation of the HP thyroid axis and dosages of thyroid hormones (THs). Serum TSH concentrations were increased, while alterations were not observed in serum concentrations of triiodothyronine and thyroxine. Regarding mRNA gene expression, Mct-8 was increased in the hypothalamus, Mct-8, Thra1, and Thrb2 were decreased in the pituitary, and Nis and Pds were reduced in the thyroid. In the heart, Mct8 and Thrb2 were increased, and Thra1 was decreased. In the liver, Mct8, Thra1, and Thrb2 were decreased. These results suggest that the consumption of relevant doses of soy isoflavones during the peripubertal period in males may induce subclinical hypothyroidism, with alterations in the regulation of the HP thyroid axis, modulation of TH synthesis, and peripheral alterations in TH target organs.

Age-dependent changes in the prognostic advantage of papillary thyroid cancer in women: A SEER-based study

BACKGROUND

Papillary thyroid cancer (PTC) is more prevalent in women, and women show a better prognosis than men; however, the factors contributing to this prognostic difference are confounding. Therefore, we aimed to investigate the effect of the interaction between sex and age on the prognosis of PTC.

METHODS

A total of 108,459 patients with PTC were retrospectively analysed, and Cox-regression models were used to assess differences in disease specific survival (DSS) by sex, with inverse probability of treatment weighting (IPTW) to control for between-group differences in prognosis by sex due to age change. Restricted cubic splines were used to analyse prognostic differences between sexes for papillary thyroid microcarcinoma (PTMC) and PTC. Multiple mediation analyses were used to assess the direct or indirect effect of sex on DSS.

RESULTS

The DSS was higher for women than men (98.6% vs. 95.4%, χ²  = 458.57, p < .001). After IPTW adjustment, the DSS of women was better than that of men (HR = 0.67, 0.60-0.76). In the subgroup analysis, women had an advantage in DSS across most age intervals (crude HR = 0.166 [0.082-0.337], p < .001, IPTW-adjusted HR = 0.331 [0.161-0.681], p < .001). The difference between the two gradually narrowed with increasing age, and the prognosis of women was better than that of men in PTMC, while this advantage was not obvious in PTC.

CONCLUSIONS

The overall PTC prognosis of women is better than that of men, but the prognostic advantage of women diminishes with age and tumour growth. These differences in prognosis may be due to some indirect factors caused by different sexes.

Hormonal Crosstalk Between Thyroid and Breast Cancer

Differentiated thyroid cancer and breast cancer account for a significant portion of endocrine-related malignancies and predominately affect women. As hormonally responsive tissues, the breast and thyroid share endocrine signaling. Breast cells are responsive to thyroid hormone signaling and are affected by altered thyroid hormone levels. Thyroid cells are responsive to sex hormones, particularly estrogen, and undergo protumorigenic processes upon estrogen stimulation. Thyroid and sex hormones also display significant transcriptional crosstalk that influences oncogenesis and treatment sensitivity. Obesity-related adipocyte alterations-adipocyte estrogen production, inflammation, feeding hormone dysregulation, and metabolic syndromes-promote hormonal alterations in breast and thyroid tissues. Environmental toxicants disrupt endocrine systems, including breast and thyroid homeostasis, and influence pathologic processes in both organs through hormone mimetic action. In this brief review, we discuss the hormonal connections between the breast and thyroid and perspectives on hormonal therapies for breast and thyroid cancer. Future research efforts should acknowledge and further explore the hormonal crosstalk of these tissues in an effort to further understand the prevalence of thyroid and breast cancer in women and to identify potential therapeutic options.

The Isoforms of Estrogen Receptor Alpha and Beta in Thyroid Cancer

The incidence of thyroid cancer was predominant in women, indicating that the sex hormone may have a role in thyroid cancer development. Generally, the sex hormone exerts its function by binding to the correspondent nuclear receptors. Therefore, aberrant of these receptors may be involved in the development of thyroid cancer. Estrogen receptor alpha (ERα) and beta (ERβ), two main estrogen receptors, have been reported to have an important role in the pathogenesis of thyroid cancer. When the ERα and ERβ genes undergo the alternative RNA splicing, some ERα and ERβ isoforms with incomplete functional domains may be formed. To date, several isoforms of ERα and ERβ have been identified. However, their expression and roles in thyroid cancer are far from clear. In this review, we summarized the expressions and roles of ERα and ERβ isoforms in thyroid cancer, aiming to provide the perspective of modulating the alternative RNA splicing of ERα and ERβ against thyroid cancer.

[Detection of DNA methylation of HYAL2 gene for differentiating malignant from benign thyroid tumors]

OBJECTIVE

To assess the value of DNA methylation level of HYAL2 gene as a molecular marker for differential diagnosis of malignant and benign thyroid tumors.

METHODS

DNA methylation of HYAL2 gene in tissue specimens of 190 patients with papillary thyroid cancer (PTC) and 190 age- and gender-matched patients with benign thyroid tumors was examined by mass spectrometry, and the protein expression of HYAL2 was detected immunohistochemically for another 55 pairs of patients. Logistic regression analysis was performed to calculate the odds ratio (OR) and evaluate the correlation of per 10% reduction in DNA methylation with PTC. Receiver operating characteristic (ROC) curve analysis was performed and the area under curve (AUC) was calculated to assess the predictive value of alterations in HYAL2 methylation.

RESULTS

Hypomethylation of HYAL2_CpG_3 was significantly correlated with early-stage PTC (OR=1.51, P=0.001), even in stage I cancer (OR=1.42, P=0.007). Age-stratified analysis revealed a significantly stronger correlation between increased HYAL2_CpG_ 3 methylation and early-stage PTC in patients below 50 years than in those older than 50 years (OR: 1.89 vs 1.37, P < 0.05); ROC analysis also showed a larger AUC of 0.787 in younger patients. The results of immunohistochemistry showed that patients with PTC had significantly higher protein expressions of HYAL2 than patients with benign tumors.

CONCLUSION

The alterations of DNA methylation level of HYAL2 gene is significantly correlated with early-stage PTC, suggesting the value of DNA methylation level as a potential biomarker for differentiation of malignant from benign thyroid tumors.

Obesity and Thyroid Cancer Risk: An Update

Thyroid cancer (TC) is the most common endocrine malignancy worldwide and its incidence has increased dramatically in recent years. In parallel, the prevalence of overweight and obesity has also increased, suggesting a possible link between these two diseases. Indeed, low-grade chronic inflammation, altered cytokine levels, insulin resistance, oxidative stress, and hormonal changes that occur in obese patients are all factors that contribute to the occurrence and growth of TC. In this review, the most recent evidence supporting the potential role of the mechanisms linking obesity to TC will be discussed.

Hormonal Replacement Therapy and Risk of Thyroid Cancer in Women: A Meta-Epidemiological Analysis of Prospective Cohort Studies

Objectives

Many experimental studies have reported that female sex hormones involve thyroid cancer development because the incidence rate of thyroid cancer in women (TCW) is 3 times higher than in men. Three previous systematic reviews reporting no association between hormone replacement therapy (HRT) and TCW risk had the same search year of 2014. The aim was to reevaluate the association between HRT use and TCW risk using a meta-epidemiological study of prospective cohort studies.

Methods

The study preferentially used all studies selected by the existing systematic reviews and then secured an additional cohort from the list citing the studies. The selection criterion was defined as the prospective cohort study assessing the association between HRT and TCW risk by adjusted relative risk and its 95% confidence intervals (CI) from multivariate analysis. A random-effects model meta-analysis was applied to estimate summary relative risk (sRR) and its 95% CI. A publication bias was evaluated by Egger’s test; moreover, the statistical significance level was set at 5%.

Results

Nine cohort studies were finally selected. The random-effect model was applied because of heterogeneity (I² = 64.3%). The sRR and its 95% CI from a random-effects model meta-analysis had no statistical significance in the association between HRT and TCW risk (sRR = 1.11; 95% CI, 0.98–1.26). Additionally, Egger’s test revealed no statistical significance (P = 0.91).

Conclusions

HRT is not associated with TCW risk based on the random-effects model meta-analysis of prospective cohort studies published until now.

Differential Effects of Estrogen Receptor Alpha and Beta on Endogenous Ligands of Peroxisome Proliferator-Activated Receptor Gamma in Papillary Thyroid Cancer

PURPOSE

The inhibition of estrogen receptor alpha (ERα) or the activation of ERβ can inhibit papillary thyroid cancer (PTC), but the precise mechanism is not known. We aimed to explore the role of ERα and ERβ on the production of endogenous peroxisome proliferator-activated receptor gamma (PPARγ) ligands in PTC.

METHODS

2 PTC cell lines, 32 pairs of PTC tissues and matched normal thyroid tissues were used in this study. The levels of endogenous PPARγ ligands 15(S)-hydroxyeicosatetraenoic acid (15(S)-HETE), 13-S-hydroxyoctadecadienoic acid (13(S)-HODE), and15-deoxy-Δ12,14-prostaglandin J2 (PGJ2) were measured by ELISA.

RESULTS

The levels of PGJ2 and 15(S)-HETE were significantly reduced in PTC, but 13(S)-HODE was not changed. Activation of ERα or inhibition of ERβ significantly downregulated the production of PGJ2, 15(S)-HETE and 13(S)-HODE, whereas inhibition of ERα or activation of ERβ markedly upregulated the production of these three ligands. Application of endogenous PPARγ ligands inhibited growth, induced apoptosis of cancer cells, and promoted the efficacy of chemotherapy.

CONCLUSION

The levels of endogenous PPARγ ligands PGJ2 and 15(S)-HETE are significantly decreased in PTC. The inhibition of ERα or activation of ERβ can inhibit PTC by stimulating the production of endogenous PPARγ ligands to induce apoptosis in cancer cells.