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

Elevated Preoperative TPO Ab Titers Decrease Risk for DTC in a Linear Fashion: A Retrospective Analysis of 1635 Cases

CONTEXT

For some, chronic lymphocytic thyroiditis (Hashimoto thyroiditis) is an important risk factor for differentiated thyroid cancer (DTC). Surgical cohort studies even suggested a potential role for thyroid peroxidase antibodies (TPO-Abs) on that risk.

OBJECTIVE

Our clinical observations argued against that possibility. We designed the present study to evaluate the relationship of TPO-Abs and DTC in a large patient population.

METHODS

We recruited individuals who underwent thyroidectomies at 4 different clinical sites (USA: 1 clinic, 2000-2013, and Greece: 3 clinics, 2007-2021). We gathered data on TPO-Abs titers measured with commercially available chemiluminescence immunoassays, and reviewed patients' data including surgical pathology. TPO-Abs of 34 IU/mL or greater was deemed positive (TPO+) and TPO-Abs less than 34 IU/mL was deemed negative (TPO-). Odds ratios (OR) for DTC were calculated with the Fisher exact test and P less than .05 was deemed significant.

RESULTS

We reviewed data from 8461 consecutive thyroid surgery cases. TPO-Abs titers were available for 1635 individuals: DTC n = 716 (43.8%), benign pathology n = 919 (56.2%), TPO+ n = 540 (33.0%), and TPO- n = 1095 (67.0%). DTC was found at a lower frequency in TPO+ (198/540, 36.7%) compared to TPO- (518/1095, 47.3%) patients, OR 0.64 (0.52-0.80; P < .0001). Rising TPO-Abs titers conferred protection against DTC in a linear fashion: TPO-Abs less than 10 IU/mL: 59.3%, TPO-Abs less than 34 IU/mL: 47.4%, TPO-Abs 34 to 100 IU/mL: 42.6%, TPO-Abs 100 to 500 IU/mL: 32.0%, TPO-Abs greater than 1000 IU/mL: 19.4%; P less than .0001.

CONCLUSION

Higher TPO-Ab titers appear protective against DTC in our large multicenter cohort of patients who underwent thyroidectomies. Rising preoperative TPO-Abs titers conferred linearly increasing protection against DTC.

The role of vascular endothelial growth factor in the development of papillary thyroid carcinoma in patients with lymphocytic thyroiditis

BACKGROUND

Vascular endothelial growth factor (VEGF) plays a pivotal role in the pathogenesis of autoimmune chronic inflammatory conditions and papillary thyroid carcinoma (PTC). We hypothesized that, as VEGF expression is increased both in PTC and in lymphocytic thyroiditis (LT), it may stimulate the development of PTC in patients with LT. To evaluate this, we examined both tumor and adjacent non-tumoral tissues of PTC patients with and without LT.

METHODS

A total of 50 patients with PTC (52.50±7.41 years) and 17 patients with nodular goiter (NG) (50.47±10.38 years) were included in the study. According to the presence of LT, patients with PTC were further divided into two groups. Immunohistochemical analyses of VEGF were conducted in all patients and for PTC patients, both tumor tissue and adjacent non-tumoral tissue were evaluated.

RESULTS

The scores for intensity of staining and percentage of labeled thyrocytes for VEGF were found to be significantly higher in the PTC patients than in the NG patients (P<0.001, P<0.001, respectively). The tumor tissue revealed similar scores for PTC patients with LT and without LT. However, the scores in adjacent non-tumoral tissue were higher in PTC patients with LT than in patients without LT (P=0.004, P=0.01, respectively).

CONCLUSIONS

To the best of our knowledge, our results are the first to demonstrate that the expression of VEGF in adjacent non-tumoral tissue were higher in PTC patients with LT than in those without, which shows a possible role of VEGF expression in the progression of PTC in the presence of LT.

The Relationship between Thyrotropin Serum Concentrations and Thyroid Carcinoma

Thyroid Stimulating Hormone (TSH) is a hormone secreted by the pituitary gland and plays a role in regulating the production and secretion of thyroid hormones by the thyroid gland. This precise feedback loop is essential for maintaining a harmonious balance of thyroid hormones in the body, which are vital for numerous physiological processes. Consequently, TSH serves as a significant marker in assessing thyroid function, and deviations from normal TSH levels may indicate the presence of a thyroid disorder. Thyroid cancer (TC) is the malignant tumor within the endocrine system. In recent years, numerous experts have dedicated their efforts to discovering efficacious biomarkers for TC. These biomarkers aim to improve the accurate identification of tumors with a poor prognosis, as well as facilitate active monitoring of tumors with a more favorable prognosis. The role of TSH in the thyroid gland underscores its potential influence on the occurrence and progression of TC, which has garnered attention in the scientific community. However, due to the limited scope of clinical research and the dearth of high-quality foundational studies, the precise impact of TSH on TC remains unclear. Consequently, we present a comprehensive review of this subject, aiming to offer a valuable reference for future research endeavors.

Stress, Thyroid Dysregulation, and Thyroid Cancer in Children and Adolescents: Proposed Impending Mechanisms

Stress is a potential catalyst for thyroid dysregulation through cross-communication of the hypothalamic-pituitary-adrenal and hypothalamic-pituitary-thyroid (HPT) axes. Stress and stressors exposure motivates molecular mechanisms affecting compound feedback loops of the HPT axis. While there is evidence of connection between stress and thyroid dysregulation, the question whether this connection is implicated in the development of thyroid cancer (TC) remains unanswered. In view of the rising incidence of TC in both adults and children alongside the increasing stress in our modern society, there is a need to understand possible interrelations between stress, thyroid dysregulation, and TC. Prolonged glucocorticoid secretion due to stress interferes with immune system response by altering the cytokines, inducing low-grade chronic inflammation, and suppressing function of immune-protective cells. Chronic inflammation is a risk factor linked to TC. The role of autoimmunity has been a matter of controversy. However, there is epidemiological connection between autoimmune thyroid disease (AITD) and TC; patients with AITD show increased incidence in papillary thyroid carcinoma (PTC), and those with TC show a high prevalence of intrathyroidal lymphocyte infiltration and thyroid autoantibodies. Timing and duration-dependent exposure to specific endocrine disrupting chemicals (EDCs) has an impact on thyroid development, function, and proliferation, leading to thyroid disease and potentially cancer. Thyroid hormone imbalance, chronic inflammation, and EDCs are potential risk factors for oxidative stress. Oxygen free radicals are capable of causing DNA damage via stimulation of the mitogen-activating protein kinase or phosphatidylinositol-3-kinase and/or nuclear factor kB pathways, resulting in TC-associated gene mutations such as RET/PTC, AKAP9-BRAF, NTRK1, RAASF, PIK3CA, and PTEN. Stressful events during the critical periods of prenatal and early life can influence neuroendocrine regulation and induce epigenetic changes. Aberrant methylation of tumor suppressor genes such as P16INK4A, RASSF, and PTEN is associated with PTC; histone H3 acetylation is shown to be higher in TC, and thyroid-specific noncoding RNAs are downregulated in PTC. This review focuses on the above proposed mechanisms that potentially lead to thyroid tumorigenesis with the aim to help in the development of novel prognostic and therapeutic strategies for TC.

Hashimoto's Thyroiditis and Papillary Cancer Thyroid Coexistence Exerts a Protective Effect: a Single Centre Experience

Papillary thyroid carcinoma (PTC) is the most common malignant tumour of the thyroid and it is often found in association with Hashimoto's thyroiditis (HT). This concomitance is still under debate. The aim of this study is to investigate the influence of Hashimoto's thyroiditis in patients with papillary thyroid carcinoma. Two thousand two hundred eighteen patients underwent thyroidectomy in our department between January 2015 and January 2020. Of these, 435 patients had surgery for papillary thyroid carcinoma and form the basis of our studies. The association between PTC and HT was found in 180 patients (41.4%), mostly represented in the female group (78.9%), with a lower median age than patients with PTC without HT. In comparison to patients with PTC alone, the PTC-HT group had less invasive and smaller tumours, as well as less lymph node involvement. Moreover, tumours of patients with PTC-HT were diagnosed earlier. Our data showed that Hashimoto's thyroiditis may be considered a protective factor when PTC develops. Furthermore, we concluded that patients with PTC and HT had a better prognosis and a lower risk of recurrence than those that did not have HT.

Autoimmune thyroid disease correlates to islet autoimmunity on zinc transporter 8 autoantibody

OBJECTIVE

The most common coexisting organ-specific autoimmune disease in patients with type 1 diabetes mellitus (T1DM) is autoimmune thyroid disease (AITD). However, there have been few clinical reports based on a large population about the prevalence of zinc transporter 8 autoantibody (ZnT8A) and other islet autoantibodies in AITD patients. We aimed to explore the presence of islet autoantibodies, ZnT8A, glutamic acid decarboxylase autoantibodies (GADA) and insulinoma-associated antigen 2 autoantibodies (IA-2A) compared with thyroid autoantibodies, thyroid peroxidase autoantibodies (TPOAb) and thyroglobulin autoantibodies (TGAb) and thyrotropin receptor autoantibodies (TRAb) in patients with Graves' disease (GD), Hashimoto's thyroiditis (HT) and T1DM patients with AITD.

METHODS

Totally, 389 patients with GD, 334 patients with HT, 108 T1DM patients with AITD and 115 healthy controls (HC) were recruited in the study. Islet autoantibodies (ZnT8A, GADA and IA-2A) were detected by radioligand binding assay. Thyroid autoantibodies, TPOAb and TGAb were detected by chemiluminescence assay, and TRAb was detected by RIA.

RESULTS

The prevalence of ZnT8A, GADA and IA-2A was higher in GD and HT patients than that of HC (ZnT8A: GD 8.48%, HT 10.8% vs HC 1.74%; GADA: GD 7.46%, HT 7.74% vs HC 0.870%; IA-2A: GD 4.88%, HT 3.59% vs HC 0%; All P < 0.05) but lower than that of T1DM subjects with AITD (ZnT8A: 42.6%; IA-2A: 44.4%; GADA: 74.1%; all P < 0.0001).

CONCLUSIONS

An increased prevalence of ZnT8A as well as GADA and IA-2A was found in both GD and HT patients, indicating that there is a potential link between thyroid autoimmunity and islet autoimmunity.

Hashimoto's thyroiditis as a risk factor for thyroid cancer

PURPOSE OF REVIEW

To summarize the recent developments in considering Hashimoto's thyroiditis as a risk factor for thyroid cancer.

RECENT FINDINGS

Modern approaches to understanding the co-occurrence of Hashimoto's thyroiditis and thyroid cancer have consistently found increased prevalence of both conditions, separately as well as of their coexistence. The inflammatory process in Hashimoto's thyroiditis is understood as a potential risk factor for thyroid cancer development. This has also provided a better understanding of the limitations in the current diagnostic and follow-up armamentarium for both conditions, resulting in international guidelines from the clinical and scientific societies. Other recent developments call for a paradigm shift in guidelines on thyroid carcinomas when lymphocytic infiltration is present, which potentially should always be considered the case at least in areas of sufficient iodine intake.

SUMMARY

The literature of Hashimoto's thyroiditis as a risk factor for thyroid cancer is reviewed over the last year to highlight new developments in the understanding of their association and future clinical implications.