Association of benign thyroid diseases with thyroid cancer risk: a meta-analysis of prospective observational studies

Tetrabromobisphenol A exerts thyroid disrupting effects but has little overt impact on postnatal brain development and neurobehaviors in mice

Tetrabromobisphenol A (TBBPA) is a widely used brominated flame retardant. There is evidence showing that TBBPA can exert thyroid disrupting effects in mammals, but different results were also reported, along with inconsistent reports regarding its neurotoxicity. Here, we investigated thyroid disrupting effects and neurotoxicity of TBBPA (5, 50, 500 µg/(kg·day)) to male mice following maternal and direct exposure through drinking water, with the anti-thyroid drug propylthiouracil (PTU) as the positive control. On postnatal day (PND) 15, we expectedly observed severe thyroid compensatory hyperplasia and cerebellar developmental retardation in PTU-treated pups. The highest dose of TBBPA also caused thyroid histological alteration but had no effects on cerebellar development in terms of Purkinje cell morphology and the thickness of the internal granular layer and the molecular layer of the cerebellum. During puberty and adulthood, the thyroid morphological alterations became more pronounced in the TBBPA-treated animals, accompanied by decreased serum thyroid hormone levels. Furthermore, the 50 and 500 µg/(kg·day) TBBPA groups showed a significant decrease in the serum level of serotonin, a neurotransmitter associated with anxiety behaviors. Correspondingly, the highest dose group displayed anxiety-like behaviors in the elevated plus-maze test on PND 35, but this neurobehavioral alteration disappeared on PND 56. Moreover, no changes in neurobehavioral parameters tested were found in TBBPA-treated animals at puberty and adulthood. Altogether, all observations show that TBBPA can exert thyroid disrupting effects but has little overt impact on brain development and neurobehaviors in mice, suggesting that thyroid disruption does not necessarily cause overtly adverse neurodevelopmental outcomes.

Association between brominated flame retardants and risk of endocrine-related cancer: A systematic review and meta-analysis

BACKGROUND

The incidence of endocrine-related cancer, which includes tumors in major endocrine glands such as the breast, thyroid, pituitary, and prostate, has been increasing year by year. Various studies have indicated that brominated flame retardants (BFRs) are neurotoxic, endocrine-toxic, reproductive-toxic, and even carcinogenic. However, the epidemiological relationship between BFR exposure and endocrine-related cancer risk remains unclear.

METHODS

We searched the PubMed, Google Scholar, and Web of Science databases for articles evaluating the association between BFR exposure and endocrine-related cancer risk. The odds ratio (OR) and its corresponding 95% confidence interval (95% CI) were used to assess the association. Statistical heterogeneity among studies was assessed with the Q-test and I2 statistics. Begg's test was performed to evaluate the publication bias.

RESULTS

We collected 15 studies, including 6 nested case-control and 9 case-control studies, with 3468 cases and 4187 controls. These studies assessed the risk of breast cancer, thyroid cancer, and endocrine-related cancers in relation to BFR levels. Our findings indicate a significant association between BFR exposure in adipose tissue and an increased risk of breast cancer. However, this association was not observed for thyroid cancer. Generally, BFR exposure appears to elevate the risk of endocrine-related cancers, with a notable increase in risk linked to higher levels of BDE-28, a specific polybrominated diphenyl ether congener.

CONCLUSIONS

In conclusion, although this meta-analysis has several limitations, our results suggest that BFR exposure is a significant risk factor for breast cancer, and low-brominated BDE-28 exposure could significantly increase the risk of endocrine-related cancers. Further research is essential to clarify the potential causal relationships between BFRs and endocrine-related cancers, and their carcinogenic mechanisms.

Prevalence of cancer in patients with hypothyroidism: Analysis using big data tools

OBJECTIVE

To evaluate the frequency of different types of cancer in patients diagnosed with hypothyroidism using big data methodology on the Savana Manager platform.

METHODS

An observational, retrospective study was carried out using electronic medical record (EMR) data from the Hospital Universitario Puerta de Hierro Majadahonda (Madrid). Information from the EMRs was extracted using artificial intelligence techniques and analysed using the Savana Manager v3.0 software. Searches were performed using the term "hypothyroidism" and the terms corresponding to the tumours analysed.

RESULTS

Of a total population of 506,749 patients, 23,570 (4.7%) were diagnosed with hypothyroidism. Patients with this diagnosis had a significantly higher frequency of cancer than that found in non-hypothyroid subjects (OR 2.09, 95% confidence interval [CI] 2.01-2.17). This higher frequency was found both in women (OR 1.99, 95% CI 1.90-2.08) and in men (OR 2.83, 95% CI 2.63-3.05). However, this higher frequency of cancer was not observed in hypothyroid patients older than 60 years (OR 0.97, 95% CI 0.92-1.02). Although the frequency of most of the neoplasms studied individually was higher in the population with hypothyroidism, we observed that hypothyroid patients over 60 years of age had a significant decrease in the frequency of prostate, lung, colorectal, and liver cancer.

CONCLUSION

Data from this hospital cohort suggest that there is a significant association between the diagnosis of hypothyroidism and cancer. However, this association is less evident in hypothyroid patients older than 60 years.

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.

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

Objective

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

Methods

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

Results

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

Conclusions

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

Biology of cancer; from cellular and molecular mechanisms to developmental processes and adaptation

Cancer research has been largely focused on the cellular and molecular levels of investigation. Recent data show that not only the cell but also the extracellular matrix plays a major role in the progression of malignancy. In this way, the cells and the extracellular matrix create a specific local microenvironment that supports malignant development. At the same time, cancer implies a systemic evolution which is closely related to developmental processes and adaptation. Consequently, there is currently a real gap between the local investigation of cancer at the microenvironmental level, and the pathophysiological approach to cancer as a systemic disease. In fact, the cells and the matrix are not only complementary structures but also interdependent components that act synergistically. Such relationships lead to cell-matrix integration, a supracellular form of biological organization that supports tissue development. The emergence of this supracellular level of organization, as a structure, leads to the emergence of the supracellular control of proliferation, as a supracellular function. In humans, proliferation is generally involved in developmental processes and adaptation. These processes suppose a specific configuration at the systemic level, which generates high-order guidance for local supracellular control of proliferation. In conclusion, the supracellular control of proliferation act as an interface between the downstream level of cell division and differentiation, and upstream level of developmental processes and adaptation. Understanding these processes and their disorders is useful not only to complete the big picture of malignancy as a systemic disease, but also to open new treatment perspectives in the form of etiopathogenic (supracellular or informational) therapies.

Malignant neoplasms in people with hypothyroidism in Spain: A population-based analysis

PURPOSE

The objective of this study was to determine the association between hypothyroidism and overall and site-specific cancer in Spanish population.

METHODS

A cross-sectional study was performed using the population-based database BDCAP (Base de Datos Clínicos de Atención Primaria, primary care clinical database) to analyze the relative risk of cancer in Spanish population with hypothyroidism.

RESULTS

In a total of 2,414,165 patients diagnosed with hypothyroidism in BDCAP in 2019, the relative risk (OR) of cancer, compared to the non-hypothyroid population, was 1.73 (1.72-1.74) (P<0.0001). The higher risk was observed in both men (OR 2.15 [2.13-2.17]; P<0.0001) and women (OR 1.67 [1.636-1.68]; P<0.0001). However, hypothyroid persons aged 65 years or older had a reduced risk of cancer (OR 0.98 [0.97-0.98]; P<0.0001). In addition, hypothyroid patients aged 65 or over showed a decreased risk of cancers of the bladder, colorectal, gastric, pancreatic and prostate. Socioeconomic characteristics such as income level, municipality size, country of birth and employment situation had limited influence on the association between hypothyroidism and cancer. However, hypothyroid patients receiving replacement therapy exhibited higher cancer risk compared with patients without treatment (OR 1.30 [1.28-1.31]; P<0.0001).

CONCLUSION

Spanish hypothyroid patients of both genders have a risk of overall cancer higher than that found in non-hypothyroid population. However, people over 65 years have a reduced risk of various malignancies. This peculiarity of hypothyroidism should be considered by the health authorities.

A Search for Causes of Rising Incidence of Differentiated Thyroid Cancer in Children and Adolescents after Chernobyl and Fukushima: Comparison of the Clinical Features and Their Relevance for Treatment and Prognosis

The incidence of differentiated thyroid cancer (DTC) is steadily increasing globally. Epidemiologists usually explain this global upsurge as the result of new diagnostic modalities, screening and overdiagnosis as well as results of lifestyle changes including obesity and comorbidity. However, there is evidence that there is a real increase of DTC incidence worldwide in all age groups. Here, we review studies on pediatric DTC after nuclear accidents in Belarus after Chernobyl and Japan after Fukushima as compared to cohorts without radiation exposure of those two countries. According to the Chernobyl data, radiation-induced DTC may be characterized by a lag time of 4–5 years until detection, a higher incidence in boys, in children of youngest age, extrathyroidal extension and distant metastases. Radiation doses to the thyroid were considerably lower by appr. two orders of magnitude in children and adolescents exposed to Fukushima as compared to Chernobyl. In DTC patients detected after Fukushima by population-based screening, most of those characteristics were not reported, which can be taken as proof against the hypothesis, that radiation is the (main) cause of those tumors. However, roughly 80% of the Fukushima cases presented with tumor stages higher than microcarcinomas pT1a and 80% with lymph node metastases pN1. Mortality rates in pediatric DTC patients are generally very low, even at higher tumor stages. However, those cases considered to be clinically relevant should be followed-up carefully after treatment because of the risk of recurrencies which is expected to be not negligible. Considering that thyroid doses from the Fukushima accident were quite small, it makes sense to assess the role of other environmental and lifestyle-related factors in thyroid carcinogenesis. Well-designed studies with assessment of radiation doses from medical procedures and exposure to confounders/modifiers from the environment as e.g., nitrate are required to quantify their combined effect on thyroid cancer risk.

A national database analysis for factors associated with thyroid cancer occurrence

In order to analyze the associations between thyroid cancer and environmental factors, we analyzed the national sample cohort representative of the entire population provided by the Korean National Health Insurance Service database record from 2006 to 2015. The cohort was categorized according to age, body mass index, income, residential areas, frequency of exercise, frequency of alcohol drinking, diet, presence or absence of hyperthyroidism, presence or absence of hypothyroidism, and smoking data. Age ≥ 55 years (HR 0.68, 95% CI 0.53–0.88), lower income (0.57, 0.40–0.80), and current smoking (0.69, 0.55–0.85) were associated with lower thyroid cancer occurrence among men. Body mass index (BMI) ≥ 25 kg/m2 (1.51, 1.26–1.82), higher income (1.44, 1.19–1.76), urban residence (1.24, 1.03–1.49), and presence of hypothyroidism (3.31, 2.38–4.61) or hyperthyroidism (2.46, 1.75–3.46) were associated with higher thyroid cancer occurrence among men. Age ≥ 55 years (0.63, 0.56–0.71), moderate alcohol drinking (0.87, 0.77–0.99), and current smoking (0.56, 0.37–0.85) were associated with lower thyroid cancer occurrence among women. BMI ≥ 25 kg/m2 (1.41, 1.26–1.57), frequent exercise (1.21, 1.07–1.36), higher income (1.18, 1.06–1.32), urban residence (1.17, 1.06–1.29), and presence of hypothyroidism (1.60, 1.40–1.82) or hyperthyroidism (1.38, 1.19–1.61) were associated with higher thyroid cancer occurrence among women. In conclusion, age ≥ 55 years and current smoking were associated with lower thyroid cancer occurrence, while BMI ≥ 25 kg/m2, higher income, urban residence, hypothyroidism, and hyperthyroidism were associated with higher occurrence in both men and women.

Association of thyroid cancer risk with plasma 25-hydroxyvitamin D and vitamin D binding protein: a case-control study in China

PURPOSE

To investigate the association of thyroid cancer (TC) with 25-hydroxyvitamin D [25(OH)D] and vitamin D binding protein (DBP) and examine whether there was an interaction between 25(OH)D and DBP in relation to TC risk.

METHODS

A matched case-control study based on multiple hospitals included 506 pairs of cases with newly diagnosed TC and controls. All subjects were divided into the quartiles according to the distribution of 25(OH)D and DBP in controls. Odds ratio (OR) and 95% confidence intervals (CIs) for the association of TC with 25(OH)D and DBP were estimated by conditional logistic regression.

RESULTS

Comparing the highest to lowest quartiles, a decreased TC risk was respectively associated with plasma 25(OH)D (OR 0.63, 95% CI 0.40-1.00, P-trend = 0.046) and DBP (OR 0.49, 95% CI 0.32-0.77, P-trend = 0.001). However, the association between DBP and TC might be modified by 25(OH)D (P-interaction = 0.014) and physical activity (P-interaction = 0.017). Compared to participants with 25(OH)D and DBP concentrations respectively below medians, those with both concentrations above medians had a lower risk of TC (OR 0.56, 95% CI 0.39-0.82). In stratified analysis based on clinical characteristics of tumor, significantly negative association between 25(OH)D, and DBP and TC were observed among the cases with early stage of tumor progression.

CONCLUSIONS

This study suggested that 25(OH)D and DBP had protective effects against TC. But the negative association between TC and DBP might be modified by 25(OH)D and physical activity.

Immunomodulatory Effects of Vitamin D in Thyroid Diseases

Vitamin D is a secosteroid with a pleiotropic role in multiple physiological processes. Besides the well-known activity on bone homeostasis, recent studies suggested a peculiar role of vitamin D in different non-skeletal pathways, including a key role in the modulation of immune responses. Recent evidences demonstrated that vitamin D acts on innate and adaptative immunity and seems to exert an immunomodulating action on autoimmune diseases and cancers. Several studies demonstrated a relationship between vitamin D deficiency, autoimmune thyroid disorders, and thyroid cancer. This review aims to summarize the evidences on the immunomodulatory effect of vitamin D on thyroid diseases.

Nutritional status and follicular-derived thyroid cancer: An update

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

Interobserver agreement and efficacy of consensus reading in Kwak-, EU-, and ACR-thyroid imaging recording and data systems and ATA guidelines for the ultrasound risk stratification of thyroid nodules

PURPOSE

To investigate the interobserver agreement (IA) and the impact of consensus reading using four risk stratification systems for thyroid nodules (TN).

METHODS

Four experienced specialists independently rated US images of 80 TN according to the Kwak-TIRADS, EU-TIRADS, ACR TI-RADS, and ATA Guidelines. The cases were randomly extracted from a prospectively acquired database (n > 1500 TN). The observers were blinded to clinical data. This study was divided into two sessions (S1 and S2) with 40 image sets each. After every session, a consensus reading was carried out (C1, C2). Subsequently, the effect of C1 was tested in S2 with 40 new cases followed by C2. Fleiss' kappa (κ) was calculated for S1 and S2 to estimate the IA and learning curves. The results of C1 and C2 were used as reference for diagnostic accuracy calculations.

RESULTS

IA significantly increased (p < 0.01) after C1 with κ values of 0.375 (0.615), 0.411 (0.596), 0.321 (0.569), and 0.410 (0.583) for the Kwak-TIRADS, EU-TIRADS, ACR TI-RADS, and ATA Guidelines in S1 (S2), respectively. ROC analysis (C1 + C2) revealed similar areas under the curve (AUC) for the Kwak-TIRADS, EU-TIRADS, ACR TI-RADS, and ATA Guidelines (0.635, 0.675, 0.694, and 0.654, respectively, n.s.). AUC did not increase from C1 (0.677 ± 0.010) to C2 (0.632 ± 0.052, n.s.). ATA Guidelines were not applicable in five cases.

CONCLUSIONS

IA and diagnostic accuracy were very similar for the four investigated risk stratification systems. Consensus reading sessions significantly improved the IA but did not affect the diagnostic accuracy.

Features and outcome of differentiated thyroid carcinoma associated with Graves' disease: results of a large, retrospective, multicenter study

BACKGROUND

Whether differentiated thyroid cancer (DTC) occurring concomitantly with Graves' disease (GD) is more aggressive and bound to a less favorable outcome is controversial.

OBJECTIVE

Aim of this multicenter retrospective study was to compare baseline features and outcome of DTC patients with GD (DTC/GD+) or without GD (DTC/GD-).

PATIENTS

Enrolled in this study were 579 patients referred to five endocrine units (Cagliari, Pavia, Pisa, Siena, and Varese) between 2005 and 2014: 193 patients had DTC/GD+ , 386 DTC/GD-. Patients were matched for age, gender and tumor size. They underwent surgery because of malignancy, large goiter size, or relapse of hyperthyroidism in GD.

RESULTS

Baseline DTC features (histology, lymph node metastases, extrathyroidal extension) did not differ in the two groups, except for multifocality which was significantly more frequent in DTC/GD+ (27.5% vs. 7.5%, p < 0.0001). At the end of follow-up (median 7.5 years), 86% of DTC/GD+ and 89.6% DTC/GD- patients were free of disease. Patients with persistent or recurrent disease (PRD) had "biochemical disease" in the majority of cases. Microcarcinomas were more frequent in the DTC/GD+ group (60% vs. 37%, p < 0.0001) and had an excellent outcome, with no difference in PRD between groups. However, in carcinomas ≥ 1 cm, PRD was significantly more common in DTC/GD+ (24.4% vs. 11.5%; p = 0.005). In the whole group, univariate and multivariate analyses showed that GD+ , lymph node involvement, extrathyroidal invasion, multifocality and tall cell histotype were associated with a worse outcome. Female gender and microcarcinomas were favorable features. No association was found between baseline TSH-receptor antibody levels and outcome. Graves' orbitopathy (GO) seemed to be associated with a better outcome of DTC, possibly because patients with GO may early undergo surgery for hyperthyroidism.

CONCLUSIONS

GD may be associated with a worse outcome of coexisting DTC only if cancer is ≥ 1 cm, whereas clinical outcome of microcarcinomas is not related to the presence/absence of GD.