Prevalence of breast cancer in thyroid diseases: results of a cross-sectional study of 3,921 patients

Genetically predicted thyroid function and risk of colorectal cancer: a bidirectional Mendelian randomization study

BACKGROUND

Observational studies have reported an association between thyroid function and colorectal cancer (CRC), with conflicting results. Elucidating the causal relationship between thyroid function and CRC facilitates the development of new preventive strategies to reduce CRC incidence.

METHOD

We applied a two-sample Mendelian randomization (MR) method to evaluate the causal relationship between five thyroid-related indexes, including hyperthyroidism, hypothyroidism, thyroid stimulating hormone (TSH), free thyroxine (FT4) and basal metabolic rate (BMR), and CRC. Genome-wide association study statistics for thyroid-related phenotypes were obtained from the ThyroidOmics consortium, and summary statistics for genetic associations with CRC were obtained from the FinnGen consortium. We set a series of criteria to screen single nucleotide polymorphisms (SNPs) as instrumental variables and then performed bidirectional MR analysis, stratified analysis and extensive sensitivity analysis. Multiplicative random-effects inverse variance weighted was the primary analysis method, supplemented by weighted median and MR-Egger.

RESULT

We identified 12 SNPs for hyperthyroidism, 10 SNPs for hypothyroidism, 41 SNPs for TSH, 18 SNPs for FT4, and 556 SNPs for BMR. Genetically predicted hyperthyroidism, hypothyroidism, TSH, and FT4 were not associated with CRC risk (all P > 0.05). Sensitivity analysis revealed no heterogeneity or pleiotropy. Genetically predicted BMR was significantly associated with increased CRC risk after removing outlier (OR = 1.30, P = 0.0029). Stratified analysis showed that BMR was significantly associated with colon cancer (OR = 1.33, P = 0.0074) but not rectal cancer. In the reverse analysis, there was no evidence of an effect of CRC on thyroid function (all P > 0.05).

CONCLUSION

Our bidirectional MR analysis provides new insights into the relationship between thyroid function and CRC. CRC prevention may benefit from enhanced screening of high BMR populations.

Insights on the Association between Thyroid Diseases and Colorectal Cancer

Benign and malignant thyroid diseases (TDs) have been associated with the occurrence of extrathyroidal malignancies (EMs), including colorectal cancers (CRCs). Such associations have generated a major interest, as their characterization may provide useful clues regarding diseases’ etiology and/or progression, with the possible identification of shared congenital and environmental elements. On the other hand, elucidation of the underlying molecular mechanism(s) could lead to an improved and tailored clinical management of these patients and stimulate an increased surveillance of TD patients at higher threat of developing EMs. Here, we will examine the epidemiological, clinical, and molecular findings connecting TD and CRC, with the aim to identify possible molecular mechanism(s) responsible for such diseases’ relationship.

Assessing the causality between thyroid and breast neoplasms: A bidirectional Mendelian randomization study

Aim

This study aimed to evaluate the association between thyroid neoplasms (TN) and the risk of developing breast neoplasms (BN) by assessing data on single nucleotide polymorphisms (SNPs) obtained from the Deutsches Krebsforschungszentrum (DKFZ) and Breast Cancer Association (BCAC).

Methods

Data on SNPs associated with TN and BN were obtained from DKFZ and BCAC, respectively. Secondary data analysis of all pooled data from genome-wide association studies (GWAS) was performed to identify the genetic loci closely associated with TN or BN as instrumental variables (IVs). To evaluate the causal relationship between TN and BN, a bidirectional Mendelian randomization (MR) analysis was performed using MR Egger regression, weighted median, inverse variance weighted (IVW) random effects model, simple mode, weighted mode, maximum likelihood, penalized weighted median, IVW radial, IVW fixed effects, and robust adjusted profile scores (RAPS) method.

Results

The MR in this study demonstrated a modest reverse causal relationship between TN and BN but a significant positive causal relationship between BN and TN.

Conclusions

The MR of this study provided genetic evidence suggesting an association between BN and TN; however, further research is warranted to explore the potential mechanism of interaction between these two malignancies. Moreover, general breast screening should be performed in individuals with TN, but TN screening should be reinforced in individuals with BN.

Thyroid and renal cancers: A bidirectional association

There is a deep interrelation between the thyroid gland and the kidney parenchyma, with dysfunction of the first leading to significant changes in renal metabolism and vice versa. Given the recognition of cancer as a systemic disease, the raise of thyroid tumors and the common association of several malignancies, such as breast cancer, prostate cancer, colorectal cancer, and other, with an increased risk of kidney disease, public health alert for these conditions is warranted. A systematic review of the current evidence on the bidirectional relationship between thyroid and renal cancers was conducted including 18 studies, highlighting patient’s characteristics, histology, time for secondary malignancy to develop from the first diagnosis, treatment, and follow-up. A total of 776 patients were identified; median age was 64 years (range: 7–76 years). Obesity and family history were identified as the most common risk factors, and genetic susceptibility was suggested with a potential strong association with Cowden syndrome. Controversy on chemo and radiotherapy effects was found, as not all patients were previously exposed to these treatments. Men were more likely to develop kidney cancer after a primary thyroid malignancy, with 423/776 (54%) experiencing renal disease secondarily. Median time after the first malignancy was 5.2 years (range: 0–20 years). With the advancement of current oncological therapy, the prognosis for thyroid cancer patients has improved, although there has been a corresponding rise in the incidence of multiple secondary malignancy within the same population, particularly concerning the kidney. Surgery can achieve disease-free survival, if surveillance follow-up allows for an early localized form, where radical treatment is recommended.

Is Melanoma Progression Affected by Thyroid Diseases?

Clinical and epidemiological evidence indicate a relationship between thyroid diseases and melanoma. In particular, the hypothyroidism condition appears to promote melanoma spread, which suggests a protective role of thyroid hormones against disease progression. In addition, experimental data suggest that, in addition to thyroid hormones, other hormonal players of the hypothalamic–pituitary–thyroid (HPT) axis, namely the thyrotropin releasing hormone and the thyrotropin, are likely to affect melanoma cells behavior. This information warrants further clinical and experimental studies in order to build a precise pattern of action of the HPT hormones on melanoma cells. An improved knowledge of the involved molecular mechanism(s) could lead to a better and possibly personalized clinical management of these patients.

Hormonal Crosstalk Between Thyroid and Breast Cancer

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

Development of Histologically Verified Thyroid Diseases in Women Operated for Breast Cancer: A Review of the Literature and a Case Series

Background: The possible relationships between breast and thyroid diseases have been reported in the literature. The purpose of our study was to evaluate the occurrence of histologically verified thyroid pathologies in women who were diagnosed with breast cancer and, after mastectomy/quadrantectomy complemented by oncological treatment, were thyroidectomized based on their periodic thyroid evaluation. Patients and Methods: Our series consist of 31 women with a mean age of 62.9 ± 10.9 years (range, 45–81) treated for breast cancer (18 right-sided, 11 left-sided, and 2 bilateral), of whom 29 were thyroidectomized, since two women who developed Graves’ disease refused thyroidectomy. These 31 women belong to a cohort of 889 women who referred to the Breast Surgery Unit of our university hospital during the period January 2010 through December 2020. Results: The mean time interval between breast cancer and thyroid pathologies was 48.1 ± 23.4 months (range, 12–95). The final diagnosis at histopathology was infiltrating ductal breast carcinoma in 26 women (with 2/26 patients having bilateral carcinoma) and infiltrating lobular breast carcinoma in the other 5 women. Ten of the twenty-nine thyroidectomized women (34.5%) had a thyroid malignancy on histology: five papillary carcinomas, three papillary micro-carcinomas and two follicular carcinomas. Two of the five women with papillary carcinoma also had histological evidence of chronic lymphocytic thyroiditis/Hashimoto’s thyroiditis, which was also detected in another five women with benign thyroid diseases. Conclusions: We suggest that breast cancer survivors should be made aware of the possible increased risk of thyroid pathologies (including thyroid malignancy) so that they can undergo screening and follow-up.

Thyroid Diseases and Breast Cancer

Epidemiological studies aimed at defining the association of thyroid diseases with extra-thyroidal malignancies (EM) have aroused considerable interest in the possibility of revealing common genetic and environmental factors underlying disease etiology and progression. Over the years, multiple lines of evidence indicated a significant relationship between thyroid carcinomas and other primary EM, especially breast cancer. For the latter, a prominent association was also found with benign thyroid diseases. In particular, a meta-analysis revealed an increased risk of breast cancer in patients with autoimmune thyroiditis, and our recent work demonstrated that the odds ratio (OR) for breast cancer was raised in both thyroid autoantibody-positive and -negative patients. However, the OR was significantly lower for thyroid autoantibody-positive patients compared to the negative ones. This is in agreement with findings showing that the development of thyroid autoimmunity in cancer patients receiving immunotherapy is associated with better outcome and supports clinical evidence that breast cancer patients with thyroid autoimmunity have longer disease-free interval and overall survival. These results seem to suggest that factors other than oncologic treatments may play a role in the initiation and progression of a second primary malignancy. The molecular links between thyroid autoimmunity and breast cancer remain, however, unidentified, and different hypotheses have been proposed. Here, we will review the epidemiological, clinical, and experimental data relating thyroid diseases and breast cancer, as well as the possible hormonal and molecular mechanisms underlying such associations.

Hormone-Related Cancer and Autoimmune Diseases: A Complex Interplay to be Discovered

Neoplasic transformation is a continuous process that occurs in the body. Even before clinical signs, the immune system is capable of recognizing these aberrant cells and reacting to suppress them. However, transformed cells acquire the ability to evade innate and adaptive immune defenses through the secretion of molecules that inhibit immune effector functions, resulting in tumor progression. Hormones have the ability to modulate the immune system and are involved in the pathogenesis of autoimmune diseases, and cancer. Hormones can control both the innate and adaptive immune systems in men and women. For example androgens reduce immunity through modulating the production of pro-inflammatory and anti-inflammatory mediators. Women are more prone than men to suffer from autoimmune diseases such as systemic lupus erythematosus, psoriasis and others. This is linked to female hormones modulating the immune system. Patients with autoimmune diseases consistently have an increased risk of cancer, either as a result of underlying immune system dysregulation or as a side effect of pharmaceutical treatments. Epidemiological data on cancer incidence emphasize the link between the immune system and cancer. We outline and illustrate the occurrence of hormone-related cancer and its relationship to the immune system or autoimmune diseases in this review. It is obvious that some observations are contentious and require explanation of molecular mechanisms and validation. As a result, future research should clarify the molecular pathways involved, including any causal relationships, in order to eventually allocate information that will aid in the treatment of hormone-sensitive cancer and autoimmune illness.

Papillary Thyroid Cancer Prognosis: An Evolving Field

Simple Summary

Over the last couple of decades, the prognostic stratification systems of differentiated thyroid cancer (DTC) patients have been revised several times in an attempt to achieve a tailored clinical management reflecting the single patients’ needs. Such revisions are likely to continue in the near future, since the prognostic value of a number of promising clinicopathological features and new molecular biomarkers are being evaluated. Here, we will review the current staging systems of thyroid cancer patients and discuss the most relevant clinicopathological parameters and new molecular markers that are potentially capable of refining the prognosis.

Abstract

Over the last few years, a great advance has been made in the comprehension of the molecular pathogenesis underlying thyroid cancer progression, particularly for the papillary thyroid cancer (PTC), which represents the most common thyroid malignancy. Putative cancer driver mutations have been identified in more than 98% of PTC, and a new PTC classification into molecular subtypes has been proposed in order to resolve clinical uncertainties still present in the clinical management of patients. Additionally, the prognostic stratification systems have been profoundly modified over the last decade, with a view to refine patients’ staging and being able to choose a clinical approach tailored on single patient’s needs. Here, we will briefly discuss the recent changes in the clinical management of thyroid nodules, and review the current staging systems of thyroid cancer patients by analyzing promising clinicopathological features (i.e., gender, thyroid auto-immunity, multifocality, PTC histological variants, and vascular invasion) as well as new molecular markers (i.e., BRAF/TERT promoter mutations, miRNAs, and components of the plasminogen activating system) potentially capable of ameliorating the prognosis of PTC patients.

Common tumor-suppressive signaling of thyroid hormone receptor beta in breast and thyroid cancer cells

The thyroid hormone receptor beta (TRβ) is a tumor suppressor in multiple types of solid tumors, most prominently in breast and thyroid cancer. An increased understanding of the molecular mechanisms by which TRβ abrogates tumorigenesis will aid in understanding the core tumor-suppressive functions of TRβ. Here, we restored TRβ expression in the MDA-MB-468 basal-like breast cancer cell line and perform RNA-sequencing to determine the TRβ-mediated changes in gene expression and associated signaling pathways. The TRβ expressing MDA-MB-468 cells exhibit a more epithelial character as determined by principle component analysis-based iterative PAM50 subtyping score and through reduced expression of mesenchymal cytokeratins. The epithelial to mesenchymal transition pathway is also significantly reduced. The MDA-MB-468 data set was further compared with RNA sequencing results from TRβ expressing thyroid cancer cell line SW1736 to determine which genes are TRβ correspondingly regulated across both cell types. Several pathways including lipid metabolism and chromatin remodeling processes were observed to be altered in the shared gene set. These data provide novel insights into the molecular mechanisms by which TRβ suppresses breast tumorigenesis.

Thyroglobulin as a negative marker for malignancy in canine and human breast tumors

Canine mammary gland tumors (CMTs) are the most common tumor type in female dogs. This study evaluated the expression pattern and role of thyroglobulin (Tg) in CMT and in human breast cancer (HBC). CMT samples were subjected to fine-needle aspiration, primary cell culture, and histopathology. The expression level of Tg was higher in benign CMT than in malignant CMT (mCMT) primary cells, particularly in the epithelial lineage. Moreover, treatment with Tg enhanced the sensitivity of doxorubicin in mCMT epithelial cells and mitigated proinflammatory response by increasing nuclear factor erythroid 2-related factor 2 (Nrf2). The proximal region of the Tg promoter was hypermethylated in mCMT epithelial cells, silencing Tg expression with concurrent downregulation of Nrf2-mediated antioxidant signaling. An identical pattern of Tg expression was observed in cytological and tissue samples. Tissue microarray analysis showed that Tg was highly expressed in normal and benign tissues when compared with their malignant counterparts, which was diminished along with higher histological grades. The survival rate was significantly higher in HBC patients with high Tg expression than those with low Tg expression. This study also showed that the progression of HBC is accompanied by the reduction of Tg expression along with augmentation of proinflammatory signaling. Our data suggested that Tg could be a negative indicator of malignancy in canine and human breast neoplasia.

Breast cancer in previously thyroidectomized patients: which thyroid disorders are a risk factor?

The aim of this study was to evaluate whether there are thyroid diseases in which breast cancer will appear later as well as the role of autoimmunity. This was a retrospective observational study. A total of 410 females (thyroid surgery and later breast cancer) and 524 females (thyroid surgery only) were compared with regard to pathological thyroid findings, thyroid hormones, thyroid autoimmunity and type of breast cancer. Thyroid autoimmunity, especially antithyroid peroxidase antibodies, significantly increased the risk of breast cancer (p < 0.01); however, this was not true for other thyroid diseases, including thyroid cancer. No variant of breast cancer was predominant, and only thyroid autoimmunity was associated with the risk of breast cancer. Further research is needed to explain the impacts of different antithyroid antibodies.

Several studies have long hypothesized a link between thyroid disease and breast cancer. The authors' study retrospectively examined a large cohort of patients who initially underwent thyroid surgery and subsequently had breast cancer compared with a control group consisting of patients with only breast cancer. This comparison showed that only autoimmune thyroid disease was a risk factor for subsequent breast cancer, whereas no significant association of thyroid cancer with breast cancer was found.

Thyroidectomy with energy-based devices: surgical outcomes and complications-comparison between Harmonic Focus, LigaSure Small Jaw and Thunderbeat Open Fine Jaw

Background

Being the thyroid gland a highly vascularized organ, achieving a meticulous hemostasis is essential to avoid serious complications. Currently, energy-based devices are widely used in thyroid surgery. The aim of this study was to compare Harmonic Focus (HF), LigaSure Small Jaw (LSJ) and Thunderbeat Open Fine Jaw (TB) in terms of surgical outcomes and complications.

Methods

Patients undergoing thyroidectomy in our Unit between January 2012 and June 2018 were retrospectively analyzed. According to the type of energy-device used, patients were divided into three groups: Group A (HF), Group B (LSJ) and Group C (TB).

Results

A total of 1,165 patients were included in this study: 1,012 in Group A, 96 in Group B and 57 in Group C. Demographic data and histopathological findings were comparable between the three groups. About the postoperative stay and complications, no statistically significant difference was found. The mean operative time was 89.41±20.60 minutes in Group A, 85.57±15.91 minutes in Group B and 78.07±17.67 minutes in Group C (P<0.01). However, the post-hoc test for all pairwise comparisons showed a statistically significant difference only between Group A and Group C.

Conclusions

HF, LSJ and TB have proved to be safe and effective. The postoperative stay and complications were comparable between the three groups. Considering the limits of our investigation, further studies are needed to investigate the effect of TB on operative times.

Association between thyroid gland diseases and breast cancer: a case-control study

BACKGROUND

At the present time, there is no consensus on the association between benign thyroid diseases and breast cancer (BC). Therefore, the aim of this study is to help shed some light on the association between hyperthyroidism, hypothyroidism, and thyroiditis and breast cancer risk.

METHODS

Use of the Disease Analyzer database (IQVIA) enabled us to perform a retrospective case-control study of 7408 women aged between 18 and 80, who were treated for an initial breast cancer diagnosis in a general practice in the United Kingdom between 2006 and 2015 (index date). Patients with a previous cancer diagnosis and an observation time of less than 12 months prior to the index date were excluded. The control group consisted of 7408 healthy women, who were matched to cases 1:1 by age, body mass index, hormone replacement therapy, and physician. The main outcome parameters of this study were the presence of thyroid disease (hypothyroidism, hyperthyroidism, struma, and thyroiditis) and the TSH values in the two groups. A univariate logistic regression model was used to investigate the association between benign thyroid diseases, TSH values, and BC.

RESULTS

The mean age was 58.4 years in both groups. We found a significant association between thyroiditis and BC (OR: 1.91, p = 0.01) and were able to refute the association between hyperthyroidism/hypothyroidism and BC. We also found that thyroid-stimulating hormone (TSH) had no significant effect on breast cancer risk.

CONCLUSION

Many experimental studies suggest a link between hyperthyroidism/hypothyroidism and BC. We were able to demonstrate an epidemiological association between thyroiditis and an increased BC risk. This shows the need for close monitoring for BC in women with thyroiditis.

Association between benign thyroid disease and breast cancer: a single center experience

BACKGROUND

The relationship between breast cancer (BC) and thyroid disease (TD) is still controversial. The aim of the study was to investigate the possible coexistence of TD in patients with newly diagnosed BC and its correlation with BC clinical presentation with regard to menopausal status and stage of disease.

METHODS

This is a retrospective cohort study of all patients treated for primary BC between 2014 and 2016 at the Breast Unit of Trieste University Hospital. Clinical charts and reports were reviewed for coexisting thyroid disorders (i.e. hyperthyroidism, hypothyroidism, benign TD, thyroid cancer, thyroid autoimmunity) and menopausal status at the time of BC diagnosis. Biomolecular profile, stage, and grading of BC were also evaluated.

RESULTS

A total of 786 women and 7 men were included in the study. Co-presence of TD was found in 161(20.3%) cases: of these, 151(19.4%) patients presented benign TD and 10(1.3%) patients presented thyroid carcinoma. Thyroid autoimmunity was found in 51(32%) patients. Regarding thyroid function, 88(55%) patients had hypothyroidism, 19(12%) hyperthyroidism, and 54(33%) normal thyroid function. No statistically significant correlation was found between age and TD (p = 0.16), although TD was more common in women aged ≥60 years. Women with BC diagnosed at pre-menopausal age were more likely to have thyroid autoimmune diseases (45% vs. 29%, p = 0.05). No association was detected among BC molecular profiles with either thyroid autoimmunity (p = 0.26) or altered thyroid function (p = 0.63). High-grade BC was more frequent in women with hyperthyroidism (52.9%, p = 0.04), but the grading was independent from the presence of thyroid autoimmune disease (p = 0.87). BC stage was related to both thyroid autoimmunity (p = 0.04) and thyroid function (p < 0.001), with 55.2% of women affected by benign TD presenting with stage I BC and more aggressive BCs found in hypothyroid patients.

CONCLUSIONS

According our study results, patients with primary BC present a greater incidence of autoimmunity disorders, especially when diagnosed in the pre-menopausal setting. However, further prospective studies are required to definitively prove causality.

The antigenic link between thyroid autoimmunity and breast cancer

The association between breast cancer and benign thyroid disorders, in particular thyroid autoimmunity, has been debated for decades. Autoantibodies to thyroid peroxidase, the hallmark of thyroid autoimmunity, have a higher prevalence among patients with breast cancer compared with the general population. Furthermore a correlation between their positivity and a better prognosis of breast cancer was found in several independent small-scale studies, even if such observation was not confirmed in a subsequent retrospective study conducted on the largest patient cohort to date. The thyroid and mammary glands present several biological similarities, therefore the hypothesis of an immune response to shared thyroid/breast antigens could in part explain the association between thyroid autoimmunity and breast cancer. The sodium iodide symporter is expressed in both glands, however it seems unlikely to be the key common antigen, considering that autoantibodies targeting it are rare. Instead thyroid peroxidase, one of the major thyroid autoantigens, is also expressed in breast tissue and therefore represents the main antigenic link between thyroid autoimmunity and breast cancer. Furthermore lactoperoxidase, an enzyme of the same family that shares structural similarities with thyroid peroxidase, is expressed in neoplastic breast cells and is responsible for the cross-reactivity with some autoantibodies to thyroid peroxidase. Novel strategies for the diagnosis and treatment of breast cancer might take advantage of the antigenic link between thyroid and breast tissues.

Genome-wide association analysis suggests novel loci underlying thyroid antibodies in Hashimoto's thyroiditis

Thyroid antibodies against thyroglobulin (TgAb) and thyroid peroxidase (TPOAb) are key markers of Hashimoto's thyroiditis (HT), the most common autoimmune thyroid disorder. Genetic determinants of thyroid antibodies are still poorly known, especially as they were not studied in patients with thyroid diseases. We performed the first genome-wide association analysis of thyroid antibodies in 430 HT patients that may be considered as population extremes for thyroid antibodies distribution. We detected two suggestively associated genetic variants with TgAb, rs6972286 close to ANKRD7 and LSM8 (P = 2.34 × 10-7) and rs756763 inside CA10 (P = 6.05 × 10-7), and one with TPOAb, rs12507813 positioned between TRIM61 and TRIM60 (P = 4.95 × 10-7). Bivariate analysis resulted with three suggestively associated genetic variants that predispose to both antibodies: rs13190616 inside RP11-138J23.1 (P = 2.01 × 10-6), rs561030786 close to DUBR (P = 7.33 × 10-6) and rs12713034 inside FSHR (P = 7.66 × 10-6). All identified genomic regions have a substantial literature record of involvement with female-related traits, immune-mediated diseases and personality traits that are all characterized by increased thyroid antibody levels. Our findings demonstrate the existence of genetic overlap between thyroid autoimmunity in HT and different non-thyroid diseases characterized by the presence of thyroid antibodies. We also suggest that genetic variants that regulate antibody levels may differ between HT patients and individuals with normal thyroid function.

A Linkage Between Thyroid and Breast Cancer: A Common Etiology?

Breast and thyroid cancers are two malignancies with highest incidence in women. These cancers often occur metachronously. Women with thyroid cancer are at increased risk for subsequent breast cancer; women with breast cancer have an increased incidence of later development of thyroid cancer, suggesting a common etiology. This bidirectional relationship is reported worldwide; however, the underlying reasons for this co-occurrence are unknown. In this review, we summarize the current epidemiologic evidence and putative mechanisms of these metachronous or synchronous cancers. Key potential causative factors are chemotherapy and radiotherapy of the primary tumor, genetic variants linking the two diseases, hormonal signaling both from the thyroid gland and from estrogens, and lifestyle and environmental factors. There is a critical need for additional epidemiologic studies focused on gender and regional incidence together with molecular investigations on common tumorigenic pathways in these endocrine cancers. Understanding the putative mechanisms will aid in the diagnosis and clinical management of both diseases.

Gynecomastia after euthyroidism restoration in a patient with type 1 diabetes and Graves' disease

In patients with autoimmune disease, gynecomastia should not be considered as 1 of the first signs of hyperthyroidism, rather it is a breast pathology that can be present even when euthyroidism restoration is achieved. It is unknown whether the autoimmune nature of thyroid disorders or simply the hyperthyroidism effects breast changes.

[Hyperthyroidism and breast cancer: Is there a link?]

The objective of this review was to determine whether there is an association between hyperthyroidism and the risk of developing a breast cancer from the analysis of data in the literature.

METHOD

The analyzed articles were extracted from the PUBMED database from 2002 to 2017 using the following keywords "hyperthyroidism AND breast cancer" and "thyroid AND breast cancer".

RESULTS

A total of 22 studies were selected, including 8 cohort studies, 12 case-control studies and 2 meta-analyzes. Of these 22 studies, 15 have established a significant epidemiological or biological link between hyperthyroidism and breast cancer. Five of them were particularly interested in Graves' disease, and four demonstrated a positive association between this disease and the onset of breast cancer, especially within three years from the thyropathy diagnosis. These different studies also highlighted the increased risk of breast cancer seen in overweight or postmenopausal women. Contradictions persist over the types of mammary cancers observed and their prognosis.

CONCLUSION

This review reveals that women with hyperthyroidism appear to have a moderately high risk of breast cancer (RR<2). These data are corroborated by solid physiopathological hypotheses. Regardless of the type of thyropathy responsible for hyperthyroidism, care should be taken to ensure that these patients receive a clinical examination of the breasts on an annual basis and mammographic screening every 2 years from the age of 50 years.

TPOAb and Thyroid Function Are Not Associated with Breast Cancer Outcome: Evidence from a Large-Scale Study Using Data from the Taxotere as Adjuvant Chemotherapy Trial (TACT, CRUK01/001)

BACKGROUND

Small-scale studies correlated the presence of thyroid autoimmunity with both improved or worsened breast cancer outcome.

OBJECTIVES

We aimed to clarify this association in a large cohort using the phase III, randomized, controlled Taxotere as Adjuvant Chemotherapy Trial (TACT, CRUK01/001).

METHODS

TACT women >18 years old with node-positive or high-risk node-negative early breast cancer (pT1-3a, pN0-1, M0), with stored plasma (n = 1,974), taken 15.5 (median; IQR 7.0-24.0) months after breast surgery were studied. Patients had also received chemotherapy (100%), radiotherapy (1,745/1,974; 88.4%), hormonal therapy (1,378/ 1,974; 69.8%), or trastuzumab (48/1,974; 2.4%). History of thyroid diseases and/or related treatments was not available. The prognostic significance of autoantibodies to thyroid peroxidase (TPOAb; positive ≥6 kIU/L), free-thyroxine and thyrotropin (combined: euthyroid, hypothyroid, hyperthyroid) was evaluated for disease-free survival (DFS), overall-survival (OS), and time-to-recurrence (TTR), with Cox regression models in univariate and multivariable analyses. The extended median follow-up was 97.5 months.

RESULTS

No difference in DFS was found by TPOAb status (unadjusted hazard ratio [HR]: 0.97, 95%CI: 0.78-1.19; p = 0.75) and/or thyroid function (unadjusted HR [hypothyroid vs. euthyroid]: 1.15, 95% CI: 0.79-1.68; p = 0.46; unadjusted HR [hyperthyroid vs. euthyroid]: 1.14, 95% CI: 0.82-1.61; p = 0.44). Similar results were obtained for OS, TTR, multivariable analyses, when TPOAb titre by tertiles was considered, and in a subgroup of 123 patients with plasma collected before adjuvant treatments.

CONCLUSIONS

No evidence for a prognostic role of TPOAb and/or thyroid function in moderate-to-high-risk early breast cancer was found in the largest and longest observational study to date.

Thyroid Autoimmunity: Role of Anti-thyroid Antibodies in Thyroid and Extra-Thyroidal Diseases

Autoimmune diseases have a high prevalence in the population, and autoimmune thyroid disease (AITD) is one of the most common representatives. Thyroid autoantibodies are not only frequently detected in patients with AITD but also in subjects without manifest thyroid dysfunction. The high prevalence raises questions regarding a potential role in extra-thyroidal diseases. This review summarizes the etiology and mechanism of AITD and addresses prevalence of antibodies against thyroid peroxidase, thyroid-stimulating hormone receptor (TSHR), and anti-thyroglobulin and their action outside the thyroid. The main issues limiting the reliability of the conclusions drawn here include problems with different specificities and sensitivities of the antibody detection assays employed, as well as potential confounding effects of altered thyroid hormone levels, and lack of prospective studies. In addition to the well-known effects of TSHR antibodies on fibroblasts in Graves' disease (GD), studies speculate on a role of anti-thyroid antibodies in cancer. All antibodies may have a tumor-promoting role in breast cancer carcinogenesis despite anti-thyroid peroxidase antibodies having a positive prognostic effect in patients with overt disease. Cross-reactivity with lactoperoxidase leading to induction of chronic inflammation might promote breast cancer, while anti-thyroid antibodies in manifest breast cancer might be an indication for a more active immune system. A better general health condition in older women with anti-thyroid peroxidase antibodies might support this hypothesis. The different actions of the anti-thyroid antibodies correspond to differences in cellular location of the antigens, titers of the circulating antibodies, duration of antibody exposure, and immunological mechanisms in GD and Hashimoto's thyroiditis.

Breast cancer and thyroid diseases: analysis of 867 consecutive cases

INTRODUCTION

The aim of this study was to evaluate the association of breast cancer with thyroid diseases. Many authors have already studied the possible relationship between these two diseases, but the results are nowadays conflicting.

MATERIALS AND METHODS

Our study examining 867 patients with breast cancer (862 women and 5 men, average age = 61 years old) of whom 141 also had thyroid disease evaluated the recurrence of thyroid diseases and their association with different types of breast cancer. Statistical analyses were performed using SPSS software for Windows; we used nonparametric tests (Chi-square and Mann-Whitney), and the level of significance was set at p < 0.05.

RESULTS

We found a significant association between breast cancer diagnosed after menopause and thyroid disease (p < 0.003). Moreover, we analyzed the role of thyroid autoimmunity identifying an association between chronic autoimmune thyroiditis and breast cancer diagnosed before menopause (p < 0.05). Regarding receptor profile of breast carcinoma, we have found an increased expression of estrogen receptors in patients with autoimmune thyroiditis compared to patients with any other thyroid diseases (p < 0.03). Contrariwise, we do not have found any difference between the group with every thyroid disease and the group without thyroid disease (p < 1.00). We did not find other statistically significant associations with breast cancer's parameters like family history, tumor size, lymph node metastasis, distant metastasis, cancer clinical and pathological stage, differentiation grade and expression of Ki67, p53 and Her2 in the two main groups with or without thyroid disease. Likewise, we did not found other statistically significant association between hypothyroidism or hyperthyroidism and breast cancer.

Risk factors for subsequent endocrine-related cancer in childhood cancer survivors

Long-term adverse health conditions, including secondary malignant neoplasms, are common in childhood cancer survivors. Although mortality attributable to secondary malignancies declined over the past decades, the risk for developing a solid secondary malignant neoplasm did not. Endocrine-related malignancies are among the most common secondary malignant neoplasms observed in childhood cancer survivors. In this systematic review, we describe risk factors for secondary malignant neoplasms of the breast and thyroid, since these are the most common secondary endocrine-related malignancies in childhood cancer survivors. Radiotherapy is the most important risk factor for secondary breast and thyroid cancer in childhood cancer survivors. Breast cancer risk is especially increased in survivors of Hodgkin lymphoma who received moderate- to high-dosed mantle field irradiation. Recent studies also demonstrated an increased risk after lower-dose irradiation in other radiation fields for other childhood cancer subtypes. Premature ovarian insufficiency may protect against radiation-induced breast cancer. Although evidence is weak, estrogen-progestin replacement therapy does not seem to be associated with an increased breast cancer risk in premature ovarian-insufficient childhood cancer survivors. Radiotherapy involving the thyroid gland increases the risk for secondary differentiated thyroid carcinoma, as well as benign thyroid nodules. Currently available studies on secondary malignant neoplasms in childhood cancer survivors are limited by short follow-up durations and assessed before treatment regimens. In addition, studies on risk-modifying effects of environmental and lifestyle factors are lacking. Risk-modifying effects of premature ovarian insufficiency and estrogen-progestin replacement therapy on radiation-induced breast cancer require further study.

The sodium iodide symporter is unlikely to be a thyroid/breast shared antigen

PURPOSE

Anti-thyroid peroxidase (TPO) autoantibodies (TPOAb) seem to be protective for patients with breast cancer (BC). Thyroid and breast tissues both express the sodium iodide symporter (NIS), similarly both have a peroxidase activity, TPO and lactoperoxidase (LPO) respectively. We hypothesize a common immune response to a thyroid/breast shared antigen suggesting three putative mechanisms: (1) TPOAb react to both TPO and LPO, (2) TPO could be expressed in BC and (3) patients with TPOAb could have autoantibodies to NIS (NISAb). Previous studies excluded NISAb that block NIS activity in sera of patients with thyroid autoimmunity (TA) and/or BC. This study investigates neutral NISAb (binding without affecting function).

METHODS

Clones of CHO cells stably expressing human NIS (hNIS; CHO-NIS) were isolated following transfection of hNIS in pcDNA3 vector. Expression of hNIS mRNA and surface protein was confirmed by PCR and flow cytometry respectively using a hNIS-mouse-monoclonal-antibody. CHO-NIS and controls transfected with the empty pcDNA3 vector (CHO-Empty) were incubated with 42 heat-inactivated human sera followed by an anti-human-IgG-AlexaFluor488-conjugate: 12 with BC, 11 with TA, 10 with both BC and TA and 9 with non-autoimmune thyroid diseases. The Kolmogorov-Smirnov Test was used to compare the fluorescence intensity obtained with CHO-NIS and CHO-Empty, using sera from six young males as a negative control population.

RESULTS

None of the 42 sera were positive for NISAb.

CONCLUSIONS

NISAb are rare and NIS is unlikely to be a common thyroid/BC shared antigen. We have recently demonstrated TPO expression in BC tissue and are currently investigating TPOAb cross-reactivity with TPO/LPO.

Breast cancer in thyroid cancer survivors: An analysis of the Surveillance, Epidemiology, and End Results-9 database

BACKGROUND

We sought to further elucidate the increased risk for breast cancer among survivors of thyroid cancer.

METHODS

Using the Surveillance, Epidemiology, and End Results-9 database, we conducted a retrospective cohort analysis on women ≥ 18 years of age with breast and thyroid cancer from 1973 to 2011.

RESULTS

A total of 707,678 breast cancer patients and 53,853 thyroid cancer patients were included; 1,750 patients developed breast cancer after a preceding diagnosis of thyroid cancer (T1B). Age-specific risk for breast cancer was greater among thyroid cancer survivors. Incidence trends showed a significant age-time interaction and suggested a difference in thyroid cancer biology as well as a treatment effect. Compared with patients with thyroid cancer only, T1B patients were older with smaller cancers, had more follicular thyroid cancers, and fewer patients received radioactive iodine. T1B patients developed breast cancer earlier than the general population, had more estrogen receptor/progesterone receptor-positive and mixed invasive tumor histology, but smaller tumors, and there is no significant difference in the number of lymph nodes involved or radiation therapy.

CONCLUSION

Thyroid cancer survivors are at greater risk for developing breast cancer than the general population. These patients develop breast cancer early, have more estrogen receptor/progesterone receptor-positive tumors, and have a greater incidence of mixed invasive cancer. Recognition of this association between thyroid and breast cancer should prompt vigilant screening in thyroid cancer survivors and further investigation into the relationship of these 2 diseases.

The prevalence of benign breast diseases in patients with nodular goiter and Hashimoto's thyroiditis

PURPOSE

The evidence regarding association between thyroid disorders and benign and malignant breast diseases is increasing. The studies exploring the relationship between thyroid and breast diseases usually have focused on thyroid autoimmunity and functions in patients with breast pathologies. In this study, we aimed to reveal the frequency of benign breast conditions in patients with nodular thyroid disease (NTD) and Hashimoto's thyroiditis (HT).

METHODS

Seventy-one women with NTD, ninety-five women with HT and seventy-two healthy people as a control group were included in the study. Serum thyroid-stimulating hormone, free triiodothyronine, free thyroxine, and thyroid peroxidase autoantibody levels were measured, and thyroid and breast ultrasonography were performed by a single operator in order to determine thyroid and breast pathology.

RESULTS

Benign breast diseases were detected in 54.9% of patients with NTD, in 47.4% of those with HT, and 29.2% of control group in the study (p < 0.01 for nodular and Hashimoto groups versus control group). Simple cyst was found to be the most frequent pathology among benign breast diseases; fibrocystic changes, mixed lesions, benign solid mass, ductal ectasia, and complex cyst followed it. No significant relation was found regarding thyroid function and autoimmunity in patients diagnosed with benign breast disease (p > 0.05).

CONCLUSIONS

The results of our study support the association between benign breast diseases and thyroid diseases. An important implication of this finding may be demonstration of the necessity of scanning for potential breast pathology in women with nodular or autoimmune thyroid disease in clinical practice.

SERUM THYROTROPIN CONCENTRATIONS ARE NOT PREDICTIVE OF AGGRESSIVE BREAST CANCER BIOLOGY IN EUTHYROID INDIVIDUALS

OBJECTIVE

The potential influence of hypothyroidism on breast cancer remains incompletely understood. The objective of this study was to investigate the relationship between serum thyrotropin (thyroid-stimulating hormone, TSH) concentration and markers of aggressive breast cancer biology as defined by receptor expression profile, tumor grade, and American Joint Committee on Cancer (AJCC) stage characteristics.

METHODS

This was a retrospective cohort study of patients from 2002 to 2014. All breast cancer patients who had complete receptor (estrogen receptor, ER; progesterone receptor, PR; and human epidermal growth factor receptor 2, Her2/neu) and prediagnosis serum TSH data (n = 437) were included. All patients had 1 of 6 receptor profiles: ER+ PR+ Her2/neu-, ER+ PR- Her2/neu-, ER+ PR+ Her2/neu+, ER+ PR- Her2/neu+, ER- PR- Her2/neu+, or ER- PR- Her2/neu-. Log-transformed serum TSH concentrations were analyzed using multinomial and logistic regressions to identify potential relationships with markers of breast cancer aggressiveness.

RESULTS

Increasing serum TSH concentration was associated with a lower probability of having the receptor expression profile ER+ PR+ Her2/neu+ compared to patients with the ER+ PR+ Her2/neu- profile (odds ratio [OR] = 0.52, P = .0045). No significant associations between other receptor expression profiles and serum TSH concentration were found. All time-weighted and unweighted median serum TSH concentrations were within normal limits. No significant associations between serum TSH concentration and tumor grade, overall AJCC stage, tumor size (T), lymph node positivity (N), or presence of metastasis (M) were observed.

CONCLUSIONS

Serum TSH was not associated with markers of breast cancer aggressiveness in our cohort.

Relationship between breast cancer and levels of serum thyroid hormones and antibodies: a meta-analysis

The breast and the thyroid are hormone responsive organs that are closely related with changes of endocrine function and glandular disease. An association between thyroid disorders and breast cancer (BC) risk has been suggested, although the results are inconclusive. The purpose of the present study was to summarize evidence supporting a relationship between BC and the level of thyroid hormones and antibodies. The MEDLINE and EMBASE electronic databases were searched for studies published between 2000 and 2014. The pooled effects were presented as weighted mean differences (WMD) with 95% confidence intervals (CI) using fixed or random effect models. We summarized the results of 8 cross-sectional studies with 4, 189 participants. The overall pooled results showed that the levels of FT3 and FT4 were significantly increased in patients with BC (WMD=1.592 pmol/l; 95% CI: 0.15-3.033 and WMD=0.461 ng/dl; 95% CI: 0.015-0.906; p=0.043). The TPOAb level in patients with BC was higher than that in the control group (WMD=81.4 IU/ml; 95% CI: 78.7-84.0; p=0.000). The overall pooled results of the TgAb with random effects analyses showed that the TgAb level was significantly increased in patients with BC (WMD=101.3 IU/ml; 95% CI: 48.7-153.9; p=0.000). The present results indicated that the serum levels of FT3, TPOAb and TgAb are significantly higher in patients with breast cancer than in healthy controls.

Antithyroid peroxidase antibody positivity is associated with lower incidence of metastasis in breast cancer

Thyroid extracts were first used to treat patients with metastatic breast cancer over a century ago. Since then, a number of studies have investigated the association between thyroid disorders and breast cancer. The presence of antibodies to thyroid peroxidase (TPOab) was recently reported to be associated with improved outcome in these patients. The aim of the present study was to evaluate the association between TPOab positivity and clinicopathological characteristics in breast cancer patients. The study included 318 newly diagnosed cases of breast cancer treated at Ondokuz Mayis University Hospital, Samsun, Turkey, between 2008 and 2012. Serum thyroid-stimulating hormone, free triiodothyronine and free thyroxine levels were measured at the time of diagnosis. Of the 318 patients, 253 were considered to be TPOab-negative (TPOab ≤34 IU/ml) and 65 TPOab-positive (TPOab >34 IU/ml). No cases with distant metastases were found in the TPOab-positive group. However, 20 (7.9%) of the 253 patients displayed distant metastases in the TPOab-negative group (P=0.01). Therefore, TPOab positivity was found to be associated with a lower incidence of metastasis in breast cancer patients.

Association of thyroid diseases with primary extra-thyroidal malignancies in women: results of a cross-sectional study of 6,386 patients

We here analyzed the prevalence of extra-thyroidal malignancies (EM) in 6,386 female patients affected by different thyroid disease (TD). At first, an age-matched analysis of EM in all patients was performed. We then evaluated EM prevalence in four TD diagnostic categories: non-nodular TD (n = 2,159); solitary nodule (n = 905); multinodular TD (n = 2,871); differentiated thyroid cancers (n = 451). Finally, patients were grouped based on the absence (n = 3,820) or presence of anti-thyroglobulin (TgAb) and/or anti-thyroperoxidase (TPOAb) (n = 2,369), or anti-Thyroid Stmulating Hormone (TSH) receptor autoantibodies (n = 197). A total of 673 EM were recorded. EM prevalence in TD patients was higher compared to the general population (Odds Ratio, OR 3.21) and the most frequent EM was breast cancer (OR 3.94), followed by colorectal (OR 2.18), melanoma (OR 6.71), hematological (OR 8.57), uterus (OR 2.52), kidney (OR 3.40) and ovary (OR 2.62) neoplasms. Age-matched analysis demonstrated that the risk of EM was maximal at age 0-44 yr (OR 11.28), remaining lower, but significantly higher that in the general population, in the 45-59 and 60-74 year age range. Breast and hematological malignancies showed an increased OR in all TD, while other cancers associated with specific TD. An increased OR for melanoma, breast and hematological malignancies was observed in both TPOAb and/or TgAb autoantibody negative and positive patients, while colorectal, uterus, kidney and ovary cancers showed an increased OR only in thyroid autoantibody negative patients. In conclusions, women affected by both benign and malignant TD, especially at a younger age and in absence of thyroid autoimmunity, have an increased risk of developing primary EM, thus requiring a careful follow-up and surveillance.