Clinical and molecular impact of concurrent thyroid autoimmune disease and thyroid cancer: From the bench to bedside

The recent incorporation of immune checkpoint inhibitors targeting the PD-1 (programmed cell death receptor 1) and CTLA-4 (cytotoxic T lymphocyte antigen 4) pathways into the therapeutic armamentarium of cancer has increased the need to understand the correlation between the immune system, autoimmunity, and malignant neoplasms. Both autoimmune thyroid diseases and thyroid cancer are common clinical conditions. The molecular pathology of autoimmune thyroid diseases is characterized by the important impact of the PD-1/PD-L1 axis, an important inhibitory pathway involved in the regulation of T-cell responses. Insufficient inhibitory pathways may prone the thyroid tissue to a self-destructive immune response that leads to hypothyroidism. On the other hand, the PD-1/PD-L1 axis and other co-inhibitory pathways are the cornerstones of the immune escape mechanisms in thyroid cancer, which is a mechanism through which the immune response fails to recognize and eradicate thyroid tumor cells. This common mechanism raises the idea that thyroid autoimmunity and thyroid cancer may be opposite sides of the same coin, meaning that both conditions share similar molecular signatures. When associated with thyroid autoimmunity, thyroid cancer may have a less aggressive presentation, even though the molecular explanation of this clinical consequence is unclear. More studies are warranted to elucidate the molecular link between thyroid autoimmune disease and thyroid cancer. The prognostic impact that thyroid autoimmune disease, especially chronic lymphocytic thyroiditis, may exert on thyroid cancer raises important insights that can help physicians to better individualize the management of patients with thyroid cancer.

Autoimmune Thyroid Disease and Differentiated Thyroid Carcinoma: A Review of the Mechanisms That Explain an Intriguing and Exciting Relationship

Autoimmune thyroid disease is a complex and highly frequent disease, where a wide variety of genetic, epigenetic and environmental factors (among others) come together and interact, and is characterized by the presence of two clinical outcomes: hypothyroidism (in Hashimoto's thyroiditis) and hyperthyroidism (in Graves-Basedow disease). For its part, differentiated thyroid carcinoma (mainly papillary carcinoma) is the most common type of cancer affecting the thyroid (and one of the most prevalent worldwide). An important co-occurrence between autoimmune thyroid disease and differentiated thyroid carcinoma has been documented. In this article, studies that have evaluated possible associations and relationships between autoimmune thyroid disease and differentiated thyroid cancer are systematically described and summarized. To date, the underlying mechanism that explains this association is inflammation; however, the characteristics and designs of the studies evaluated do not yet allow a causal relationship between the two entities to be established. These aspects have made it difficult to establish "causality" in the continuum of the pathogenesis between both conditions.

Ultrasound, laboratory and histopathological insights in diagnosing papillary thyroid carcinoma in a paediatric population: a single centre follow-up study between 2000-2022

Background

Papillary thyroid carcinoma (PTC) often coincides with autoimmune thyroiditis (AIT); whether this association is incidental or causal remains debated.

Objective

To evaluate the ultrasonographic, laboratory, and histopathological features of PTC in paediatric patients with and without AIT and its relationship to puberty.

Design

A retrospective cohort study.

Patients and methods

A retrospective analysis of medical records of 90 patients (69; 76.7% females). The mean age at PTC diagnosis was 13.8 years [range 6-18]. All patients were evaluated ultrasonographically before thyroid surgery. Thyroid nodules were categorised using the European Thyroid Imaging Reporting and Data System (EU-TIRADS PL), and cytopathology was assessed using Bethesda criteria. Neck ultrasound results and thyroid and autoimmune status were correlated with histopathological PTC assessment.

Results

The coexistence of PTC and AIT was found in 48.9% (44/90) of patients. The percentage of AIT was increasing with age; AIT was present only in 1/3 of prepubertal, close to 50% in pubertal, and over 60% in adolescent patients. The youngest patients (aged <10 years old) presented more often with goitre and lymphadenopathy and less often with AIT than adolescents (15-18 years of age). There were no differences in TPOAb, TgAb, and TSH levels between the age subgroups. Presurgical TgAb levels were higher than those of TPOAb in the youngest patients. Histopathological analysis revealed that the solid subtype was observed more often in prepubertal children and diffuse sclerosing in children below 14 years of age, whereas the classic subtype dominated in late pubertal. Univariate and multivariate analyses revealed that lymph nodes metastases (LNM) were associated with PTC diameter and fT4 level, whereas extrathyroidal extension with age and angioinvasion with PTC diameter and age. The correlations between age and fibrosis, and the presence of psammoma bodies in malignant tissues were close to significant. We did not observe an association between TSH levels and the presence of autoimmunity and PTC variables.

Conclusions

In paediatric patients the natural course of PTC may be less aggressive in adolescent patients than in younger children (especially < 10 years of age). We suggest that pre-operative evaluation of paediatric patients with thyroid nodules could include apart from assessment of thyroid hormones, evaluation of TPOAb, TgAb, and TRAb together with comprehensive neck ultrasonography.

Association between chronic lymphocityc thyroiditis and papillary thyroid carcinoma: Systematic review and meta-analysis of studies on surgical specimens

Introduction. Inconsistent results exist in the literature regarding the hypothesis statement suggesting an increased likelihood of documenting papillary thyroid carcinoma (PTC) in surgical specimens with changes compatible with chronic lymphocytic thyroiditis. Existing meta-analyses have included studies that are not methodologically comparable and do not propose clear sources of bias, thus, this is justification for the present meta-analysis. Methods. A literature search in PubMed and Embase was performed from January 1, 1950 to December 31, 2020. Retrospective studies comparing the prevalence of papillary thyroid carcinoma in specimens with and without chronic lymphocytic thyroiditis changes were obtained. The collected evidence was statistically analyzed. Results. A total of 22 articles were included. The study population consisted of 63,548 surgical specimens. The pooled OR, based on the studies, was 1.81 (95% CI: 1.51-2.21). There was heterogeneity between the distribution of prevalence ratios and opportunity ratios across studies (I²= 91%; p>0.00001). The funnel plot shape of the studies included in the analysis appears to be symmetrical, indicating the absence of bias attributable to small studies. Conclusions. The current literature suggests that there is an increased risk of documenting papillary thyroid carcinoma in surgical specimens in which chronic lymphocytic thyroiditis-compatible changes are observed; however, there are sources of bias that will not be possible to control for in retrospective studies, so we recommend studying the hypothesis suggesting an increased likelihood of diagnosing PTC in specimens with chronic lymphocytic thyroiditis-compatible changes using prospective methodologies.

Prognostic value of the preoperative and early trends in postoperative serum thyroglobulin antibody levels among patients with papillary thyroid carcinoma and concomitant Hashimoto's thyroiditis

BACKGROUND

Thyroglobulin antibody(TgAb) was generally used as a prognostic marker of papillary thyroid cancer(PTC) only after total thyroidectomy, but its value in PTC patients with concomitant Hashimoto's thyroiditis(HT) is unclear. We aimed to assess the prognostic significance of the serum TgAb in these patients.

METHODS

This retrospective cohort study included PTC patients and pathologically proven HT from 2007-2016. The Cox proportional hazards model with restricted cubic spline was used to analyze the association between TgAb and structural recurrence, and then survival analysis was performed.

RESULTS

Of 839 patients enrolled, 48 recurrences were identified during a median follow-up of 64 months. Macrocarcinoma and lymph node metastasis were significantly associated with higher TgAb (P = 0.006, 0.002), but no significant difference was found for any other characteristics. An increasing preoperative TgAb level up to 2000 IU/ml was associated with shorter recurrence-free survival(RFS) (P < 0.001), and the 5-year RFS rates in patients with TgAb ≤400, 400-800 and >800 IU/ml were 97.3%, 93.2% and 85.8%, respectively (P < 0.05). The difference was found even after adjusting for potential risk factors (P < 0.001). Of 337 PTC patients who were treated with lobectomy and had available TgAb data at the first year after surgery, a significant decrease (≥50%) in postoperative TgAb was achieved in 41.8% patients, who had a favorable prognosis compared with others (5-year RFS rate 98.5% vs. 92.0%, P = 0.008).

CONCLUSIONS

The preoperative serum TgAb seem to effectively stratify PTC patients with concomitant HT who had high risk for recurrence, and the early postoperative trends of TgAb was a good prognostic marker for these patients who treated with lobectomy.

Elastographic Evaluation of Thyroid Nodules in Children and Adolescents with Hashimoto’s Thyroiditis and Nodular Goiter with Reference to Cytological and/or Histopathological Diagnosis

There are data indicating the coexistence of papillary thyroid carcinoma and autoimmune thyroiditis (AIT) in children. The aim of the study was elastographic evaluation of thyroid nodules in children and adolescents with AIT and nodular goiter in relation to cytological and/or histopathological diagnosis. We examined 215 children (57 boys and 158 girls) with 261 thyroid nodules (143 non-AIT and 118 AIT). All study participants underwent a conventional ultrasound examination with elastography followed by fine needle aspiration biopsy (FNAB). Abnormal Strain Ratio (SR ≥ 5) was observed in 36 non-AIT nodules and 15 AIT nodules. Papillary thyroid carcinoma was diagnosed in 5 patients (2% of all investigated nodules). SR of malignant thyroid nodules was statistically higher in comparison to SR of benign nodules both in the group of non-AIT (6 ± 4 vs. 3.67 ± 2.62, p = 0.024) and AIT nodules (6.3 ± 0.01 vs. 2.92 ± 1.89, p = 0.047). Comparison of non-AIT and AIT benign nodules revealed that SR was higher in non-AIT nodules (3.67 ± 2.62 vs. 2.92 ± 1.89, p = 0.01). We observed a strong positive correlation (R = 1) between TSH concentration and SR ratio in the group of all malignant thyroid nodules. Autoimmune inflammatory process of the thyroid gland does not limit the use of elastography in the diagnosis of thyroid nodules in children.

Association between Hashimoto thyroiditis and clinical outcomes of papillary thyroid carcinoma: A meta-analysis

Objective

To assess association between Hashimoto thyroiditis (HT) and clinical outcomes of papillary thyroid carcinoma (PTC).

Methods

Databases including Pubmed, Embase, Cochrane Library, and Web of Science were searched. Weighed mean differences (WMDs) and odds ratios (ORs) were used to evaluate association between HT and clinical outcomes of PTC, and the effect size was represented by 95% confidence intervals (CIs). Heterogeneity test was performed for each indicator. If the heterogeneity statistic I²≥50%, random-effects model analysis was carried out, otherwise, fixed-effect model analysis was performed. Sensitivity analysis was performed for all outcomes, and publication bias was tested by Begg’s test.

Results

Totally 47,237 patients in 65 articles were enrolled in this study, of which 12909 patients with HT and 34328 patients without HT. Our result indicated that PTC patients with HT tended to have lower risks of lymph node metastasis (OR: 0.787, 95%CI: 0.686–0.903, P = 0.001), distant metastasis (OR: 0.435, 95%CI: 0.279–0.676, P<0.001), extrathyroidal extension (OR: 0.745, 95%CI: 0.657–0.845, P<0.001), recurrence (OR: 0.627, 95%CI: 0.483–0.813, P<0.001), vascular invasion (OR: 0.718, 95%CI: 0.572–0.901, P = 0.004), and a better 20-year survival rate (OR: 1.396, 95%CI: 1.109–1.758, P = 0.005) while had higher risks of multifocality (OR: 1.245, 95%CI: 1.132–1.368, P<0.001), perineural infiltration (OR: 1.922, 95%CI: 1.195–3.093, P = 0.007), and bilaterality (OR: 1.394, 95%CI: 1.118–1.739, P = 0.003).

Conclusions

PTC patients with HT may have favorable clinicopathologic characteristics, compared to PTCs without HT. More prospective studies are needed to further elucidate this relationship.

Coexistence of Histologically Proven Chronic Lymphocytic Thyroiditis with Other Thyroid Disorders: A Retrospective Study

Background  Hashimoto's thyroiditis (HT) is the commonest autoimmune thyroid pathology. It has been reported in increased numbers recently, probably due to the increase in autoimmune diseases across many parts of the world. It is sometimes found associated with other diseases as well as other diseases of the thyroid. There is an unproven association of this condition with thyroid cancer, particularly papillary thyroid carcinoma (PTC).

Methods  This was a retrospective study performed over a period of 5 years. The objectives of this study were to find out the prevalence of histopathologically proven HT in surgically resected thyroid glands for various indications and its association with other thyroid disorders, especially thyroid malignancies. Total 4,630 patients who underwent thyroidectomy during the study period and met the criteria for inclusion were considered for analysis.

Results  Histopathologically proven features of HT were present in 1,295 (28%) of the cases. Among these, 445 (34.36%) had only HT while 850 (65.66%) had HT along with other thyroid diseases. The most common disease associated with HT was multinodular goiter (44.2%), followed by PTC (15.2%). Patients with HT exhibited a higher rate of papillary cancer (16.7%) compared with patients without this pathology (13.8%). Statistically significant association between papillary cancer and HT was found among the female patients.

Conclusion  The prevalence of HT in patients undergoing thyroidectomy is high in the studied population. A statistically significant association exists between papillary thyroid cancer and thyroiditis among female patients. This could form the basis for further research along these lines.

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.

Histopathological Types of Papillary Thyroid Carcinoma: Clinicopathologic Study

BACKGROUND: Papillary thyroid carcinoma (PTC) is the most common type of thyroid carcinoma that represents a set of characteristic of nuclear features in which the diagnosis is depend. AIM: The study aimed to review different variants of PTC which has different malignant potential in correlation with many prognostic and clinical factors in Iraq. PATIENTS AND METHODS: Paraffin blocks of 227 cases of PTC were selected, subtyped, and grouped according to the malignant potential. The prognostic and clinical factors were studied. RESULTS: The mean age was (39.29 ± 12.17) years, with female predominance (86.3%), where (55.5%) of them below 40 years, conventional variant was most common (40.1%), followed by papillary microcarcinoma variant, 197 cases (86.8%) were classified as low to intermediate malignant potential, and 30 cases (13.2%) were classified as high malignant potential. On comparison, among the tumor stages, tumor focality, native capsular invasion, lymph nodes involvement, presence or absence of vascular invasion, extrathyroid extension, and distant metastasis, there is no significant correlation between them, whereas with the tumor size, there is significant correlation between them (p =< 0.05). CONCLUSION: Conventional type followed by micropapillary type is most common. The mean age in Iraqi patients is lower than other countries for PTC. There is no significant association regarding prognostic factors between low to intermediate malignant potential variants and high malignant potential variants with exception of tumor diameter.

Hashimoto's Thyroiditis: A "Double-Edged Sword" in Thyroid Carcinoma

BACKGROUND

The prevalence of thyroid carcinoma (TC) and Hashimoto's thyroiditis (HT) has been increasing dramatically over the past decades. We investigated the relationship between HT and TC.

METHODS

We followed the Meta-analysis of Observational Studies in Epidemiology (MOOSE) guidelines for carrying out and reporting this meta-analysis. The literature from January 1, 2010 to December 31, 2020, regardless of region and publication type, was searched comprehensively in PubMed, Embase, Web of Science, and Cochrane Library databases. After careful selection and data extraction, the pooled odds ratio of various clinical characteristics in 39 studies were calculated. Publication bias was analyzed using funnel plots.

RESULTS

Meta-analysis of 39 original research articles showed HT to be a risk factor of TC (pooled odds ratio = 1.71; 95% confidence interval, 1.57-1.80; p < 0.00001) and papillary thyroid carcinoma (1.67, 1.51-1.85, <0.00001). Patients with papillary thyroid carcinoma (PTC) combined with HT were more likely to have multifocal carcinomas. The prevalence of an extrathyroidal extension, metastasis, BRAF^V600E mutation, and recurrence was significantly lower in patients with PTC combined with HT.

CONCLUSIONS

HT is a "double-edged sword" in TC patients. HT increases the risk of TC and PTC but is a protective factor against PTC progression.

Cancer Risk in Hashimoto's Thyroiditis: a Systematic Review and Meta-Analysis

OBJECTIVE

Research data suggest that patients with Hashimoto's thyroiditis may increase the risk of cancer. However, existing research is inconsistent with this view. Therefore, to investigate the effect of Hashimoto's thyroiditis on the risk of developing cancer, we conducted this study.

METHODS

We searched the PubMed and Embase databases from database establishment until March 2022. After rigorous literature screening by two authors, 23 studies that met the inclusion criteria were identified, and the required data were independently extracted.

RESULTS

We retrieved 3591 records, and after the screening, 11 case-control studies and 12 cohort studies were included in the analysis. Data analysis suggested that patients with Hashimoto's thyroiditis had an increased risk of developing breast cancer, urogenital cancer, digestive organs cancer, hematologic cancer, and a low risk of respiratory cancers.

CONCLUSIONS

This systematic review and meta-analysis showed that patients with HT may have a significantly increased risk of thyroid cancer, breast cancers, lung cancer, digestive system cancer, urogenital cancers, blood cancers, and prolactinoma people without HT.

SYSTEMATIC REVIEW REGISTRATION

https://www.crd.york.ac.uk/prospero/, identifier CRD 42022320741.

Hashimoto's thyroiditis in papillary thyroid carcinoma: a 22-year study

Objective

We retrospectively investigated whether there is a relationship between Hashimoto's thyroiditis (HT) and papillary thyroid carcinoma and studied the effect of HT on prognostic factors.

Methods

1080 patients, who underwent thyroidectomy in our hospital and received a diagnosis of papillary thyroid carcinoma, were included in the study. In histopathological specimens, the diagnosis of papillary thyroid carcinoma was reconfirmed and non-neoplastic areas in the same specimen were evaluated in terms of HT.

Results

HT was detected in non-neoplastic areas of specimens in 36.1% (n = 390) of 1080 patients with a diagnosis of papillary thyroid carcinoma whereas HT was not observed in 63.9% (n = 690). There was a significant positive correlation between presence of HT and multifocal location (p < 0.05, χ2 = 38.5). There was no significant relationship between extrathyroidal tissue invasion and HT (p > 0.05).

Conclusion

We assume that patients with HT developing papillary thyroid carcinoma have an increased risk of having multifocal tumour, and thus surgical intervention should be tailored according to this risk.

The Association Between Chronic Lymphocytic Thyroiditis and the Progress of Papillary Thyroid Cancer

BACKGROUND

Whether chronic lymphocytic thyroiditis (CLT) influences the risk of development and the progression of papillary thyroid cancer (PTC) remains uncertain. We investigated the effects of CLT on the clinicopathologic features and prognosis of PTC.

METHODS

Two thousand nine hundred twenty-eight consecutive patients with PTC treated between 2009 and 2017 were divided into two groups: one with chronic lymphocytic thyroiditis and one without; 1174 (40%) of the patients had coincident CLT.

RESULTS

In univariate analysis, CLT correlated positively with small tumor size, frequent extrathyroidal extension, multifocal diseases, and p53 but negatively with central lymph node (LN) metastasis and BRAF mutation. In multivariate analysis, CLT was associated with extrathyroidal extension and multifocal disease; however, it was not a prognostic factor for recurrence even though it was associated with two aggressive factors. Compared with patients with PTC alone, there were more retrieved central LNs in the PTC + CLT group, and these patients also underwent more invasive diagnostic tests such as fine needle aspiration cytology and frozen biopsy of LN.

CONCLUSIONS

The CLT patients with PTC had better behavior features and prognoses than did those with PTC alone despite frequent multifocality and extrathyroidal extension. However, precaution may be necessary to avoid performing invasive diagnostic procedures for lateral LN metastasis and to manage the patients appropriately.

Investigating Antithyroglobulin Antibody As a Prognostic Marker for Differentiated Thyroid Cancer: A Meta-Analysis and Systematic Review

Background: Serum thyroglobulin (Tg) is used in the follow-up of patients with differentiated thyroid cancers (DTC), but the presence of antithyroglobulin antibodies (TgAbs) makes Tg measurements unreliable. TgAb decline after total thyroidectomy and persistent/increasing levels may indicate cancer persistence/recurrence. Hence, we aimed to determine whether TgAb might be a reliable prognostic marker for DTC. Methods: We conducted a meta-analysis and systematic review. A comprehensive literature search was performed to identify studies of patients with DTC with known TgAb status and prognostic outcomes in five databases (Medline, Embase, PubMed, Google Scholar, and Scopus). We used a random-effects model to calculate pooled odds ratios (ORs) and 95% confidence intervals (CIs) for TgAb status and its association with DTC prognosis. Results: After analysis of 34 studies, we found that TgAb+ patients have a higher risk of lymph node metastasis (OR = 1.18 [CI 1.47-2.25]) and cancer persistence/recurrence (OR = 2.78 [CI 1.55-4.98]) than TgAb- patients. However, no significant differences in mean/median tumor size, risk of extrathyroidal extension, tumor multifocality, and cancer mortality were found between the two groups. In a comparison of TgAb trends, patients with persistent/increasing TgAb levels were found to have a higher risk of cancer persistence/recurrence (OR = 9.90 [CI 4.36-22.50]) and cancer mortality (OR = 15.18 [CI 2.99-77]) than patients with decreasing TgAb levels. Conclusions: TgAb positivity and persistent/increasing trends were associated with compromised DTC prognosis. These results suggest that TgAb may be used as a prognostic marker in the follow-up of patients with DTC.

Association between chronic lymphocytic thyroiditis and papillary thyroid carcinoma: A retrospective study in surgical specimens

INTRODUCTION

The hypothesis of an association between papillary thyroid carcinoma (PTC) and chronic lymphocytic thyroiditis (CLT) continues to generate debate. Retrospective studies suggest that there is a greater probability of diagnosing a PTC in surgical specimens with CLT; however, prospective studies suggest that there is no true increase in risk.

METHODS

An analytical, cross-section measurement and retrospective study was carried out considering gender, age and diagnosis of CLT and PTC in surgical specimens. A binary logistic regression model was proposed to predict the probability of carrying out the diagnosis of PTC based on the diagnosis of CLT, gender and age.

RESULTS

The study population consisted of 1136 patients, 1047 (92.2%) women and 89 (7.8%) men, with an average age of 47.5±14.3 years. The prevalence of CLT and PTC was 14.9% and 16.1% respectively. Coexistence between PTC and CLT was found in 44 patients, corresponding to 3.9% of the population. Our logistic regression model suggests that the probability of diagnosing PTC in surgical specimens of male patients under 40 years old and with CLT is 53.8%.

CONCLUSIONS

We suggest that there is a greater probability of diagnosing PTC in surgical specimens with confirmatory histological data for CLT; in addition, in males under 40 years old this probability increases.

Dynamics of serum antithyroglobulin antibodies in patients with differentiated thyroid cancer

PURPOSE

Serum antithyroglobulin antibodies (sTgAb) affect the reliability of Tg measurement in patients with thyroid cancer. We compared the outcome of patients with detectable and undetectable sTgAb, stratified according to the initial risk of recurrence (RR); also the response to treatment in patients with detectable sTgAb treated with total thyroidectomy (TT) with and without radioiodine remnant ablation (RA) and the sTgAb trend in the long-term follow-up according to the initial response.

METHODS

We included 432 patients submitted to TT, with or without RA; 106 patients had detectable sTgAb levels. Median follow-up was 53 months.

RESULTS

There were no statistically significant differences considering presentation between negative or positive sTgAb subjects. The frequency of structural incomplete response (SIR) in low, intermediate, and high RR was similar. Undetectable sTgAb in patients was achieved in a median of 16 months in ablated patients compared with 11 months in those without RA (p = 0.0232). Patients without RA had a higher rate of undetectable sTgAb during the first 12 months. A SIR was observed in 3% of patients with declining sTgAb, in 19% of those with stable levels, and in 43% with increasing sTgAb (p = 0.004). The status of no evidence of disease was achieved more frequently in patients with initial sTgAb levels < 200 mUI/l, independently of the initial RR.

CONCLUSIONS

There was no impact of sTgAb on the initial clinical presentation and the response to therapy in low-risk patients treated with or without RA. sTgAb trend is more useful than an absolute value to predict a SIR.

The Role of Surgery in Autoimmune Conditions of the Thyroid

The two most common autoimmune conditions of the thyroid include chronic lymphocytic (Hashimoto's) thyroiditis and Graves' disease. Both conditions can be treated medically, but surgery plays an important role. Hashimoto's thyroiditis and Graves' disease are mediated by autoantibodies that interact directly with the thyroid, creating inflammation and impacting thyroid function. Patients may develop large goiters with compressive symptoms or malignancy requiring surgical intervention. In addition, there are several surgical indications specific to Hashimoto's and Graves' Disease.

Thyroid Carcinoma Coexisting with Hashimoto's Thyreoiditis: Clinicopathological and Molecular Characteristics Clue up Pathogenesis

Thyroid cancer (TC) coexisting with Hashimoto’s thyroiditis (HT) presents with several characteristic features including multifocality and lower clinical stages compared to de novo carcinomas but its exact biology is still not understood. We reexamined clinico-pathological and molecular correlations between Hashimoto’s thyroditis and papillary thyroid cancer. A total of 262 patients with TC was evaluated who underwent thyroidectomy at the Surgical Department of the University of Debrecen. Clinical data, histology and molecular data were evaluated. Our cohort included 43 patients (16.4%) with (5 male, 38 female) and 219 (83.6%) patients without coexisting HT (48 male, 171 female). Hashimoto’s thyroiditis related thyroid cancer presented predominantly (93.0% of the cases) with the papillary histological type. Multifocality was observed more frequently with coexisting HT (16/40; 40.0%) compared to cases uninvolved (45/190; 23.7%)(p = 0.034). In contrast, lymphatic metastasis (pN1) with a significantly reduced frequency in patients with HT (4/11; 36.4%) then without HT (34/41 pN1; 82.9%)(p = 0.002). BRAF V600E mutation could be demonstrated at significantly lower rates in cases of PTC + HT (32.1 vs 60.7%, p < 0.005). High incidence, multifocality and papillary morphology strongly support a causal relation between TC and preexisting Hashimoto’s thyroiditis, the latter to be considered as a preneoplastic condition promoting thyroid carcinogenesis.

Influence of Hashimoto Thyroiditis on the Development of Thyroid Nodules and Cancer in Children and Adolescents

It is unclear whether patients with Hashimoto thyroiditis (HT) are predisposed to develop thyroid nodules and/or thyroid cancer. The objective of our study was therefore to assess the prevalence of thyroid nodules and/or cancer in patients with HT and to look for possible prognostic factors. A retrospective survey of 904 children/adolescents with HT (709 females, 195 males) regularly followed in nine Italian centers of pediatric endocrinology was performed. Median period of follow-up was 4.5 years (1.2 to 12.8 years). We evaluated free T4, TSH, thyroid peroxidase antibody (TPOAb), thyroglobulin antibodies, and thyroid ultrasound yearly. One hundred seventy-four nodules were detected, with an annual incidence rate of 3.5%. Ten nodules were malignant (8 papillary and 2 papillary follicular variant), giving a 5.7% prevalence of cancer among patients with nodules. The severity of hypoechogenity at ultrasound, TPOAb, and free T4 serum concentrations were predictive for the appearance of new nodules. Furthermore, a positive correlation was observed between TPOAb titer and the development of thyroid cancer. In conclusion, HT seems to influence the development of thyroid nodules, but not cancer in children and adolescents.

Clinical Applicability of Low Levels of Thyroglobulin Autoantibodies as Cutoff Point for Thyroglobulin Autoantibody Positivity

BACKGROUND

Thyroglobulin (Tg) is an established tumor marker in differentiated thyroid carcinoma (DTC). However, Tg assays can be subject to interference by autoantibodies against Tg (TgAbs). No clinical consensus exists on the cutoff value of TgAb positivity and its relationship to Tg assay interference. The aims of this study were to investigate the most applicable cutoff value for TgAb positivity in clinical practice and to evaluate whether tumor characteristics differ between TgAb+ and TgAb- patients during ablation therapy using the manufacturer's cutoff (MCO) and institutional cutoff (ICO).

METHODS

This single-center cohort study included 230 DTC patients diagnosed between January 2006 and December 2014. Serum Tg and TgAbs were measured with the Tg-IRMA (Thermo Fisher Scientific) and ARCHITECT Anti-Tg (Abbott Laboratories) assays. Patients were divided into TgAb- and TgAb+ based on the limit of detection (LoD; ≥0.07 IU/mL), functional sensitivity (FS; ≥0.31 IU/mL), MCO (≥4.11 IU/mL), and ICO (≥10 IU/mL).

RESULTS

All patients were TgAb+ based on the LoD; one patient was negative on FS. Fifty-five (23.9%) and 34 (14.8%) patients had TgAbs above the MCO and ICO, respectively. Histology, presence of multifocality, tumor-node-metastasis, and American Thyroid Assocation risk stratification did not differ between TgAb- and TgAb+ patients using MCO and ICO during ablation.

CONCLUSIONS

This study supports the use of a higher cutoff value than that of the FS for TgAb positivity in clinical settings. The LoD and FS are too sensitive to discriminate TgAb positivity and negativity in DTC patients during ablation therapy. The presence of TgAbs during ablation is not related to tumor characteristics and risk profile. This implies that TgAb positivity should not be considered a separate risk factor.

Associations between Hashimoto Thyroiditis and Clinical Outcomes of Papillary Thyroid Cancer: A Meta-Analysis of Observational Studies

BACKGROUND

Epidemiological studies have suggested an association between Hashimoto thyroiditis (HT) and papillary thyroid cancer (PTC) development. Other studies, however, have reported a protective role of HT against PTC progression. Through this updated meta-analysis, we aimed to clarify the effects of HT on the progression of PTC.

METHODS

We searched citation databases, including PubMed and Embase, for relevant studies from inception to September 2017. From these studies, we calculated the pooled odds ratios (ORs) of clinicopathologic features and the relative risk (RR) of PTC recurrence with 95% confidence intervals (CIs) using the Mantel-Haenszel method. Additionally, the Higgins I² statistic was used to test for heterogeneity.

RESULTS

The meta-analysis included 71 published studies with 44,034 participants, among whom 11,132 had HT. We observed negative associations between PTC with comorbid HT and extrathyroidal extension (OR, 0.74; 95% CI, 0.68 to 0.81), lymph node metastasis (OR, 0.82; 95% CI, 0.72 to 0.94), distant metastasis (OR, 0.49; 95% CI, 0.32 to 0.76), and recurrence (RR, 0.50; 95% CI, 0.41 to 0.61).

CONCLUSION

In this meta-analysis, PTC patients with HT appeared to exhibit more favorable clinicopathologic characteristics and a better prognosis than those without HT.

Thyroid Nodules in Pediatric Patients: Sonographic Characteristics and Likelihood of Cancer

Purpose To determine the relationship between demographic and sonographic characteristics of thyroid nodules and malignancy in a pediatric population. Materials and Methods All thyroid nodules in patients younger than 19 years that underwent ultrasound (US)-guided fine-needle aspiration biopsy between January 2004 and July 2017 were retrospectively identified. Age, sex, and background appearance of the thyroid gland were recorded for each patient, and sonographic characteristics and pathologic diagnosis were recorded for each nodule. Demographic and sonographic characteristics were assessed to determine which were associated with malignancy. Categorical and continuous variables and interobserver variability were assessed. Results A total of 404 nodules in 314 patients (82.8% female) (age range, 2-18 years; mean age, 14.9 years) were analyzed. A total of 77 nodules (19.1%) were malignant, the majority of which were papillary thyroid carcinoma (n = 68 [88.3%]). The likelihood of malignancy did not differ between boys and girls (27.8% vs 22.7%, P = .64), nor did it differ between prepubertal and pubertal patients (18.8% vs 19.1%, P > .99). The cancer rate in patients with a solitary nodule was higher than that in patients with multiple nodules (29.4% vs 14.2%, P = .003). Sonographic characteristics associated with malignant nodules included larger size, solid parenchyma, taller-than-wide shape, presence of speckled calcifications, lack of a smooth margin, and presence of abnormal lymph nodes. Interobserver variability for assessment of sonographic characteristics ranged from moderate to very strong. Conclusion In children with thyroid nodules, solitary nodules, larger nodule size, solid parenchyma, taller-than-wide shape, speckled calcifications, irregular margins, and abnormal lymph nodes raise concern for malignancy.

High prevalence of papillary thyroid carcinoma in nodular Hashimoto's thyroiditis at the first diagnosis and during the follow-up

BACKGROUND

The association between Hashimoto's thyroiditis (HT) and papillary thyroid carcinoma (PTC) remains to be elucidated.

MATERIALS AND METHODS

A total of 484 HT patients were retrospectively subdivided into two groups: 243 without thyroid nodules, TNs (HTN-) and 241 with TNs (HTN+). Fine-needle aspiration cytology was available in 152 HTN+ patients. This group was compared to a group of 161 patients with nodular goiter (NG) without HT. Finally, 70 HTN+ and 37 NG patients underwent surgery.

RESULTS

A very high prevalence of suspicious/malignant cytology (Thy 4-5) at the first diagnosis (38/124; 31%) and during the follow-up (6/28; 22%) was found in HTN+ group. In HTN- group, 22/130 (17%) patients developed TN, but none showed malignant features during the follow-up. HTN+ patients had higher prevalence of Thy 4-5 (44/152 = 28.9%) compared to NG patients (12/161 = 7.4%, p < 0.0001). Increased independent odds ratio (OR) for malignancy was conferred by serum TSH > 1.0 μUI/ml, [OR 1.93, 95% confidence interval (CI) 1.41-2.64, p < 0.0001], male sex (OR 3.44, CI 1.48-8.02, p = 0.004) and HT (OR 3.14; CI 1.08-9.31, p < 0.05). Malignant histology (mostly PTC) was confirmed higher in HTN+ (48/70, 68.6%) compared to NG (15/37, 40.5%; p < 0.05). Higher prevalence of extrathyroidal infiltration (24/48, 50%) and vascular invasion (25/48, 52%) was found in HTN+ vs NG (2/15, 1.3% p < 0.01), (3/16, 1.8% p < 0.05), respectively.

CONCLUSIONS

This study confirms higher prevalence of suspicious/malignant cytology and PTC at histology in nodular HT compared to NG, without evidence of malignancy in non-nodular HT patients during the follow-up.

Prognostic value of preoperative anti-thyroglobulin antibody in differentiated thyroid cancer

CONTEXT

The coexistence of differentiated thyroid cancer (DTC) and thyroid autoimmune disease could represent a better or worse prognosis. This study investigated the prognostic importance of preoperative anti-thyroglobulin antibody (TgAb) in DTC patients.

DESIGN AND PATIENTS

This retrospective hospital-cohort study enrolled 1171 consecutive DTC patients with preoperative TgAb data, who underwent total thyroidectomy between January 2006 and December 2011. Clinical parameters studied included demographics, primary tumour characteristics, radioiodine therapy, thyroid function tests, preoperative thyroglobulin (Tg) and TgAb levels, and cancer persistence/recurrence.

RESULTS

A total of 254 (21.7%) patients were preoperatively TgAb positive. The percentage positive for thyroid peroxidase (TPO) antibody and lymphocytic thyroiditis was significantly higher in the TgAb-positive group. The TgAb-positive group had a significantly higher rate of lymphatic invasion and lymph node metastasis both overall and in patients without TPOAb and lymphocytic thyroiditis (non-HT group). The mean number of total and central lymph nodes dissected and rate of lateral lymph node dissection were significantly higher in the TgAb-positive group, both overall and in non-HT patients. In regression analysis, preoperative TgAb was an independent risk factor for lateral lymph node metastasis. Over 50.2±14.5 months of follow-up, disease persistence/recurrence was not significantly different between patients with and without TgAb, both overall and in non-HT patients. Preoperative TgAb showed no significant correlation with final disease status.

CONCLUSION

Positive preoperative serum TgAb is associated with worse primary tumour characteristics but rarely showed poor prognosis, probably due to more aggressive treatment of these subjects.

Thyroid Autoimmunity and Thyroid Cancer: Review Focused on Cytological Studies

The association between Hashimoto thyroiditis (HT) and papillary thyroid carcinoma (PTC) has been originally suggested by retrospective pathological studies and has recently been re-evaluated and proposed on the basis of several fine-needle aspiration cytology (FNAC) studies. In FNAC studies, the association between HT and PTC is based on the comparison of anti-thyroid autoantibodies (ATA) (anti-thyroperoxidase [TPOAb] and anti-thyroglobulin [TgAb]), thyroid function (TSH), and cytology with histology of thyroid nodules and lymphocytic thyroid infiltration (LTI) of operated thyroid glands. Most of the pathological studies found a high prevalence rate of PTC in HT. In most FNAC studies, the risk ratio of PTC in HT patients was evaluated using multivariate statistical analysis: increased TSH levels represented the main and common independent risk factor of malignancy, although it resulted not consistently related to HT. On the other hand, several studies provided a positive relationship between ATA and PTC, particularly with TgAb. Two recent FNAC studies from the same referral center clearly demonstrated an independent risk for thyroid malignancy conferred by both TPOAb and TgAb, confirming the role of increased TSH levels, and found a significant association between PTC and ATA and diffuse LTI at histology. These studies are consistent with the hypothesis that autoimmune thyroid inflammation and increased serum TSH concentration may be involved in thyroid tumor growth. The complex relationship between HT and PTC, which involves immunological/hormonal pathogenic links, needs to be further investigated with prospective studies.

A meta-analysis of Hashimoto's thyroiditis and papillary thyroid carcinoma risk

OBJECTIVE

It remains inconclusive whether Hashimoto's thyroiditis (HT) predisposes patients to the development of papillary thyroid carcinoma (PTC). We conducted a meta-analysis of the available data to address this question.

RESULTS

Twenty-seven eligible studies were selected, including 18 archival thyroidectomy studies, 6 fine-needle aspiration (FNA) studies, and 3 selective FNA or thyroidectomy studies. A total of 76,281 patients, including 12,476 cases of thyroid cancer, were included in these studies. The mean rate of PTC among patients with HT ranged from 1.12% (selective FNA or thyroidectomy studies) to 40.11% (thyroidectomy studies). All three types of studies supported the correlation between HT and PTC. The overall pooled odds ratio (OR) of the PTC risk for HT (HT versus non-HT) was 2.12 (95% confidence interval [CI]: 1.78-2.52).

METHODS

We searched all relevant published studies using the citation databases PubMed and Embase. The ORs and corresponding 95% CIs were calculated by the random-effects model for the association between HT and PTC.

CONCLUSIONS

Our meta-analysis confirmed that HT predisposed patients to the development of PTC.

The Effects of Hashimoto Thyroiditis on Lymph Node Metastases in Unifocal and Multifocal Papillary Thyroid Carcinoma: A Retrospective Chinese Cohort Study

The purpose of this study was to investigate the risk factors for central and lateral neck lymph node metastases in papillary thyroid carcinoma (PTC) and multifocal papillary thyroid carcinoma (MPTC), particularly when associated with Hashimoto thyroiditis (HT).A retrospective analysis of 763 consecutive patients who underwent total thyroidectomy with bilateral central neck dissection in the First Affiliated Hospital, College of Medicine, Zhejiang University between October 2011 and October 2014 was conducted. All patients had formal histological diagnoses of HT. Multivariable logistic regression analysis was performed to identify risk factors of neck lymph node metastases.Our study identified 277 PTC patients with HT and showed comparatively low rates of central lymph node metastases (CLNM) compared with the PTC patients without HT (37.2% versus 54.7%, P < 0.001). There were no statistically significant differences in lateral lymph node metastases (LLNM) (P = 0.656). Neck lymph node metastases were histologically proven in 127 (45.8%) patients with PTC with HT, including 103 CLNM and 24 LLNM. There were no significant differences in LLNM between the MPTC-associated HT and classic MPTC cases; however, a significantly reduced risk of CLNM was observed in the MPTC-associated HT compared with the MPTC cases (35.7% versus 72.4%, respectively, P < 0.001). In the multivariate analysis, HT was identified as an independent alleviating factor for CLNM in all PTC patients (odds ratio, 0.369; 95% confidence interval (CI), 0.261 to 0.521; P < 0.001) and in MPTC patients (odds ratio, 0.227; 95% CI, 0.126-0.406; P < 0.001). A cut-off of thyroid peroxidase antibody >140 IU/mL was established as the most sensitive and specific level for the prediction of MPTC based on receiver operating characteristic curve analyses. Thyroid peroxidase antibody, age, tumor size, and multifocality exhibited the ability to predict CLNM in PTC with HT patients with an area under the curve of 81.1% based on a multivariate model.Hashimoto thyroiditis was associated with increased prevalences of multifocality and capsular invasion. In contrast, HT was associated with a reduced risk of CLNM in PTC and MPTC patients, which indicated a potential protective effect. We found that the prognostic prediction model was applicable for predicting multifocality and CLNM in PTC patients with HT.

Nodules in autoimmune thyroiditis are associated with increased risk of thyroid cancer in surgical series but not in cytological series: evidence for selection bias

BACKGROUND

The association of thyroid cancer and autoimmune thyroiditis (AIT) has been widely addressed, with conflicting results in surgical and cytological series, likely affected by selection bias.

OBJECTIVE

The objective of the study was to evaluate the association between the cytological features suggestive or indicative of malignancy and AIT in 2504 consecutive patients (2029 females and 475 males, mean age 58.3 ± 14.1 y) undergoing fine-needle aspiration cytology for thyroid nodules.

PATIENTS

Based on the clinical diagnosis, patients were divided into four groups: AIT with nodules (N-AIT, 14.9%); nodular Graves disease (N-GD, 2.8%); nodular goiter and negative thyroid antibodies (NGAb-, 68.4%); and nodular goiter with positive thyroid antibodies (NGAb+, 13.9%).

RESULTS

The prevalence of patients with cytological features suggestive (Thy4) or indicative of malignancy (Thy5) was 4.5 % in the N-AIT group, not different compared with the other groups (N-GD, 5.6%; NGAb-, 5.0%; NGAb+, 4.3%). No difference was also found in the other categories (Thy2 and Thy3). When the same analysis was performed in the subgroup of patients (14.3%) with a histological confirmation, we found that the prevalence of differentiated thyroid cancer was significantly higher (P = .01) in the N-AIT group (67.8%) compared with the other groups (N-GD, 40.0%; NGAb-, 37.2%; NGAb+, 36.9%).

CONCLUSIONS

The results of our cytological series do not support a link between N-AIT and thyroid cancer. The association between cancer and N-AIT found in the histology-based series is likely due to a selection bias represented by the fact that the prevalent indication for surgery in the N-AIT group was suspicious cytology (60.7% of patients) more frequently than in the other groups.

Coexistence of thyroglobulin antibodies and thyroid peroxidase antibodies correlates with elevated thyroid-stimulating hormone level and advanced tumor stage of papillary thyroid cancer

The correlation between thyroglobulin antibodies (TgAb) or thyroid peroxidase antibodies (TPOAb) and papillary thyroid cancer (PTC) remains controversial. This histological study aimed to explore the correlation between thyroid autoantibodies (TAb), thyroid-stimulating hormone (TSH), and PTC in patients with thyroid nodules (TN). This was a retrospective study. 2,132 non-autoimmune thyroid diseases (AITD) patients who underwent thyroidectomy were subdivided into: TgAb or TPOAb single positive (TgAb+ or TPOAb+) TN group; TgAb and TPOAb double positive or negative (TAb+ or TAb-) TN group. PTC patients showed a higher rate of TAb+ TN (10.24 vs. 4.89 %; P = 0.000) and a higher TSH level (1.83 ± 0.07 vs. 1.39 ± 0.03 mIU/L; P = 0.000) than patients with benign nodules. TAb+ TN patients showed a higher TSH level and PTC frequency than those with TAb- TN (1.91 ± 0.17 vs. 1.47 ± 0.03 mIU/L; P = 0.011) (41.35 vs. 22.08 %; P = 0.000). In PTC, TAb+ TN patients showed a higher TSH level (2.57 ± 0.35 vs. 1.79 ± 0.07 mIU/L; P = 0.032), a greater frequency of lymph node metastasis (52.73 vs. 36.51 %, P = 0.026), and a lower micro-PTC frequency (16.36 vs. 39.51 %; P = 0.001) than TAb- TN patients. PTC was correlated with TgAb+ TN (OR = 1.921, CI 1.431-2.580; P = 0.000), TPOAb+ TN (OR = 1.945, CI 1.195-3.165; P = 0.007), TAb+ TN (OR = 2.393, CI 1.635-3.501; P = 0.000), and serum TSH >1.35 mIU/L (OR = 1.742, CI 1.089-2.786; P = 0.021). Serum positive TgAb or TPOAb is an independent predictor for PTC regardless of AITD. The coexistence of TgAb and TPOAb confers a greater risk for PTC than isolated positive TgAb or TPOAb, and is correlated with elevated TSH level and advanced PTC stage.

Coexistence of papillary thyroid cancer and Hashimoto thyroiditis in children: report of 3 cases

This report documents 3 pediatric papillary thyroid carcinoma cases with associated Hashimoto thyroiditis. In all 3 cases, hypoechoic nodules accompanied by multiple echogenic spots were noted on sonography of the thyroid. Hashimoto thyroiditis was suspected on the basis of positive thyroid autoantibody test results and pathologic examinations of thyroidectomy specimens, which revealed chronic thyroiditis with lymphocytic infiltration as the background of papillary thyroid carcinoma development. The potential for papillary carcinoma development warrants close follow-up, and meticulous sonographic examinations must be performed in children with Hashimoto thyroiditis.

Risk-based ultrasound screening for thyroid cancer in obese patients is cost-effective

BACKGROUND

A higher body mass index (BMI) is associated with more advanced stages of thyroid cancer. Screening obese patients for thyroid cancer has been proposed but has yet to be examined for cost-effectiveness. The objective of this study was to assess the cost-effectiveness of ultrasound (US) screening of obese patients for thyroid cancer.

METHODS

A decision-tree model compared cost savings for the following: (i) base case scenario of an obese patient with thyroid nodule found by palpation, (ii) universal US screening of all obese patients, and (iii) risk-based US screening in obese patients. Risk-based screening consisted of patients who had at least one of four major identified risk factors for thyroid cancer (family history of thyroid cancer, radiation exposure, Hashimoto's thyroiditis, and/or elevated thyrotropin). Patients with nodules underwent established treatment and management guidelines. The model accounted for recurrence, complications, and long-term treatment/follow-up for five years. Outcome probabilities were identified from a literature review. Costs were estimated using a third-party payer perspective. Sensitivity analyses were performed to examine the impact of risk factor prevalence and US cost on the model.

RESULTS

The resulted costs per patient were $210.73 in the base case scenario, $434.10 in the universal US screening arm, and $166.72 in the risk-based screening arm. Risk-based screening remained cost-effective until more than 14% of obese patients had risk factors and with a wide variation of US costs ($0-$1113).

CONCLUSION

Risk-based US screening in selected obese patients with risk factors for thyroid cancer is cost-effective. Recommendations for screening this subgroup will result in cost savings and a likely decreased morbidity and mortality in this subpopulation with more aggressive disease.

The association between papillary thyroid carcinoma and histologically proven Hashimoto's thyroiditis: a meta-analysis

OBJECTIVE

No consensus exists on the association between papillary thyroid carcinoma (PTC) and Hashimoto's thyroiditis (HT). To resolve this controversy, this study aimed to evaluate the relationship between the two conditions using a meta-analysis.

METHODS

We searched relevant published studies using citation databases including PubMed, Embase, and ISI Web of Science. The effect sizes of clinicopathologic parameters were calculated by odds ratio (OR), weighted mean difference, or hazard ratio (HR). The effect sizes were combined using a random-effects model.

RESULTS

Thirty-eight eligible studies including 10 648 PTC cases were selected. Histologically proven HT was identified in 2471 (23.2%) PTCs. HT was more frequently observed in PTCs than in benign thyroid diseases and other carcinomas (OR=2.8 and 2.4; P<0.001). PTCs with coexisting HT were significantly related to female patients (OR=2.7; P<0.001), multifocal involvement (OR=1.5; P=0.010), no extrathyroidal extension (OR=1.3; P=0.002), and no lymph node metastasis (OR=1.3; P=0.041). Moreover, PTCs with HT were significantly associated with long recurrence-free survival (HR=0.6; P=0.001).

CONCLUSIONS

Our meta-analysis showed that PTC is significantly associated with pathologically confirmed HT. PTC patients with HT have favorable clinicopathologic characteristics compared with PTCs without HT. However, patients with HT need to be carefully monitored for the development of PTC.

Clinical Review: Hashimoto's thyroiditis and papillary thyroid carcinoma: is there a correlation?

CONTEXT

The link between Hashimoto's thyroiditis (HT) and papillary thyroid cancer (PTC) has long been a topic of controversy. There are conflicting reports; some suggest that these two are positively correlated, whereas other studies report no relationship.

EVIDENCE ACQUISITION

We performed a systematic literature review of original studies that investigated the correlation between HT and PTC. The two main search engines used to identify articles were OVID Medline and PubMed. The included studies were categorized into a fine-needle aspiration biopsy (FNAB) group and an archival thyroidectomy specimen group.

EVIDENCE SYNTHESIS

There is no clear evidence to support the correlation between HT and PTC. Population-based FNAB studies report no linkage, whereas many of the studies of thyroidectomy specimens report a positive relationship. The average prevalence rate of PTC in patients with HT was 1.20% in 8 FNA studies of 18 023 specimens and 27.56% in 8 archival thyroidectomy studies of 9 884 specimens. The relative risk ratio of finding evidence of PTC in HT specimens ranged from .39 to 1.00 in the FNA group (average RR = .69) in contrast to 1.15 to 4.16 from the archival thyroidectomy studies (average RR = 1.59). In addition, there are many studies in the literature that propose a genetic link between HT and PTC involving the PI3K/Akt pathway and RET/PTC gene rearrangements.

CONCLUSION

Although limited by the lack of definitive pathology, population-based FNA studies did not find a statistically significant correlation between HT and PTC. Thyroidectomy studies, which reported a statistically significant positive correlation, are subject to selection bias. More prospective studies with longer follow-up are needed to further elucidate this relationship.