Profile of thyroid hormones in breast cancer patients

Altered hormone expression induced genetic changes leads to breast cancer

PURPOSE OF REVIEW

Breast cancer ranks first among gynecological cancer in India. It is associated with urbanization, changes in lifestyle and obesity. Hormones also play a crucial role in the development of breast cancer. Steroid hormones play critical role in development of breast cancer.

RECENT FINDING

Breast cancer is caused due to alteration in different hormone expressions leading to genetic instability. Loss or gains of functions due to genetic instability were associated with the alterations in housekeeping genes. Up-regulation in c-myc, signal transducer and activator of transcription (STAT), CREB-regulated transcription coactivator (CRTC), and eukaryotic translation initiation factor 4E (eIF4E) may cause the development of breast cancer. Peptide hormones are commonly following the phosphoinositide 3-kinases (PI3K) pathway for activation of cell cycle causing uncontrolled proliferation. Although steroid hormones are following the Ras/Raf/mitogen-activated protein kinase (MEK) pathway, their hyper-activation of these pathways causes extracellular-signal-regulated kinase (ERK) and MAPK activation, leading to carcinogenesis.

SUMMARY

Alteration in cell cycle proteins, oncogenes, tumor suppressor genes, transcription and translation factors lead to breast cancer. Apoptosis plays a vital role in the elimination of abnormal cells but failure in any of these apoptotic pathways may cause tumorigenesis. Hence, a complex interplay of hormonal and genetic factors is required to maintain homeostasis in breast cells. Imbalance in homeostasis of these hormone and genes may lead to breast cancer.

Breast cancer, breast cancer-directed radiation therapy and risk of hypothyroidism: A systematic review and meta-analysis

OBJECTIVE

Breast cancer and breast cancer-directed radiation therapy (RT) may increase the risk of late effects, such as hypothyroidism. We conducted a systematic review and meta-analysis to investigate the association between breast cancer, RT, and risk of hypothyroidism in breast cancer survivors.

METHODS

Through February 2022, we searched PubMed, EMBASE, and references of relevant articles, to identify papers on breast cancer and breast cancer-directed RT and subsequent risk of hypothyroidism. Articles were screened by title and abstract and reviewed for eligibility. We used a pre-formed data extraction sheet and identified key design elements that could potentially introduce bias. The main outcome was the confounder-adjusted relative risk (RR) of hypothyroidism in breast cancer survivors versus women without breast cancer, and in breast cancer survivors according to the receipt of RT to the supraclavicular lymph nodes. We used a random-effects model to calculate pooled RRs and associated 95% confidence intervals (95% CI).

RESULTS

From 951 papers screened by title and abstract, 34 full-text papers were reviewed for eligibility. We included 20 studies published between 1985 and 2021-19 were cohort studies. Compared with women without breast cancer, the pooled RR of hypothyroidism in breast cancer survivors was 1.48 (95% CI: 1.17, 1.87), with highest risk associated with RT to the supraclavicular region (RR = 1.69, 95% CI: 1.16, 2.46). The most important limitations of the studies were small sample size yielding estimates with low precision, and lack of data on potential confounders.

CONCLUSION

Breast cancer and radiation therapy to the supraclavicular lymph nodes is associated with an increased risk of hypothyroidism.

Clinical characteristics and survival of second primary breast carcinoma with extramammary malignancies

Objectives

To investigate the characteristics, diagnosis, survival and prognosis of second primary breast carcinoma (SPBC).

Materials and methods

Records of 123 patients with SPBC in Tianjin Medical University Cancer Institute & Hospital between December 2002 and December 2020 were retrospectively reviewed. Clinical characteristics, imaging features and survival were analyzed and comparisons between SPBC and breast metastases (BM) were made.

Results

Of 67156 newly diagnosed breast cancer patients, 123 patients (0.18%) suffered previous extramammary primary malignancies. Of the 123 patients with SPBC, approximately 98.37%(121/123)were female. The median age was 55 years old (27-87). The average diameter of breast mass was 2.7 cm (0.5-10.7). Approximately 77.24% (95/123) of the patients presented with symptoms. The most common types of extramammary primary malignancies were thyroid, gynecological cancers, lung, and colorectal. Patients with the first primary malignant tumor of lung cancer were more likely to develop synchronous SPBC, and those with the first primary malignant tumor of ovarian cancer were more likely to develop metachronous SPBC. When comparing with BM, patients with SPBC were more often older (≥45 years old), at earlier stages (I/II), more microcalcification and less multiple breast masses in imaging. More than half (55.88%) of patients in the metachronous group developed primary breast cancer within 5 years after diagnosis of extramammary primary cancer. The median overall survival time was 71 months. Within 90 months, the prognosis of patients with synchronous SPBC was worse than that of patients with metachronous SPBC (p=0.014). Patients with BM had the worst outcome compared with patients with synchronous SPBC and metachronous SPBC (p<0.001).ER/PR-negative status, an interval of less than 6 months between the onset of two tumors, a late stage of first primary malignancy, and an age of diagnosis of first primary malignancy greater than 60 years predicted a worse prognosis for patients with SPBC.

Conclusion

The possibility of SPBC should be considered during the follow-up of patients with primary extramammary malignancy, especially within 5 years of the onset of the first tumor. The stage of first primary malignancy and the age at diagnosis of first primary malignancy have an impact on the prognosis of patients with SPBC.

Anti-TPO antibody and thyroid hormone levels in Iranian female breast cancer patients and their association with prognostic factors: a case-control study

The aim of this study was to assess prevalence of anti-thyroid peroxidase (anti-TPO) antibody and thyroid hormones in Iranian female breast cancer patients, compare them to a control population, and investigate their association with prognostic factors. In this case-control study, breast cancer patients were selected from a surgery clinic in a tertiary hospital and control group participants were enrolled from those who had visited for mammography screening. Participants with any history of thyroid disease, or thyroid related medication were excluded from both groups. Groups were assessed for levels of thyroid stimulating hormone (TSH), T3, T4, and anti-TPO. In addition, the status of estrogen receptors (ER), progesterone receptors (PR), and human epidermal growth factor receptor 2 (HER2) was determined for cancer patients. Overall 69 participants (39 cancer patients and 30 controls) were included. Difference in serum anti-TPO levels between the two groups was not statistically significant (p-value: 0.184). While a significant difference was observed for T4 and TSH levels between groups (p-value: 0.034 and <0.001, respectively), T3 levels did not reveal any significant difference (p-value: 0.177). In addition, ER, PR, and HER2 status were not correlated with anti-TPO levels. This results can serve as preliminary evidence that thyroid autoimmunity is not correlated with breast cancer incidence in Iranian female population. However, additional studies with larger sample sizes are required for more conclusive evidence.

The effect of thyroid dysfunction on breast cancer risk: an updated meta-analysis

In a previous systematic review and meta-analysis of studies reporting associations between hyper-/hypothyroidism and breast cancer incidence published through 29 January 2019, we identified a higher risk with diagnosed hyperthyroidism compared to euthyroidism, but no association with diagnosed hypothyroidism. This 2-year updated meta-analysis aims to investigate the role of menopause in this association and the dose-response relationship with blood levels of thyroid-stimulating hormone (TSH) and thyroid hormones. After the exclusion of studies with only mortality follow-up, with thyroid dysfunction evaluated as a cancer biomarker or after prior breast cancer diagnosis, we reviewed 25 studies that were published up to 01 December 2021 and identified in MEDLINE, the COCHRANE library, Embase, or Web of Science; of these, 9 were included in the previous meta-analysis. Risk estimates from 22 of the 25 studies were included in the meta-analysis and pooled using random-effects models. Compared to euthyroidism, hyperthyroidism and hypothyroidism diagnoses were associated with higher (pooled risk ratio (RR): 1.12, 95% CI: 1.06-1.18, 3829 exposed cases) and lower risks (RR = 0.93, 95% CI: 0.86-1.00, 5632 exposed cases) of breast cancer, respectively. The increased risk after hyperthyroidism was greater among postmenopausal women (RR = 1.19, 95% CI 1.09-1.30) and the decreased risk after hypothyroidism was more pronounced among premenopausal women (RR = 0.69, 95% CI 0.53-0.89). Among women with no prior history of thyroid disease, every 1 mIU/L increase in TSH level was associated with a 0.8% (95% CI > 0-1.5%) lower risk of breast cancer. In conclusion, this meta-analysis supports an association between thyroid hormone levels and breast cancer risk, which could be modified by menopausal status.

The TSH/Thyroid Hormones Axis and Breast Cancer

Breast cancer, the most prevalent female carcinoma, is characterized by the expression of steroid nuclear receptors in a subset of cases. The most important nuclear receptor with prognostic and therapeutic implications is the Estrogen Receptor (ER), which is expressed in about three out of four breast cancers. The Progesterone Receptor (PR) and the Androgen Receptor (AR) are also commonly expressed. Moreover, non-steroid nuclear receptors, including the vitamin D receptor (VDR) and the thyroid receptors (TRs), are also present in breast cancers and have pathophysiologic implications. Circulating thyroid hormones may influence breast cancer risk and breast cancer cell survival, through ligating their canonical receptors TRα and TRβ but also through additional membrane receptors that are expressed in breast cancer. The expression of TR subtypes and their respective isotypes have diverse effects in breast cancers through co-operation with ER and influence on other cancer-associated pathways. Other components of the TSH/thyroid hormone axis, such as TSH and selenoiodinase enzymes, have putative effects in breast cancer pathophysiology. This paper reviews the pathophysiologic and prognostic implications of the thyroid axis in breast cancer and provides a brief therapeutic perspective.

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.

Effects of thyroxine on apoptosis and proliferation of mammary tumors

Hypothyroidism is a protective factor against breast cancer but long-term exposure or overdoses of thyroid replacement therapy with thyroxine (T₄) may increase breast cancer risk.

OBJECTIVE

to study, in vivo and in vitro, the effects of T4 on the proliferation and apoptosis of mammary tumors of hypo- and euthyroid rats, and the possible mechanisms involved in these effects.

MATERIAL AND METHODS

Female Sprague-Dawley rats were treated with a single dose of dimethylbenzathracene (15 mg/rat) at 55 days of age and were divided into three groups: hypothyroidism (HypoT; 0.01% 6-N-propyl-2-thiouracil -PTU- in drinking water, n = 20), hypothyroidism treated with T₄ (HypoT + T₄; 0.01% PTU in drinking water and 0.25 mg/kg/day T₄ via sc; n = 20) and EUT (untreated control, n = 20). At sacrifice, tumor explants from HypoT and EUT rats were obtained and treated either with 10^-10 M T₄ in DMEM/F12 without phenol red with 1% Charcoalized Fetal Bovine Serum or DMEM/F12 only for 15 min to evaluate intracellular signaling pathways associated with T₄, and 24 h to evaluate changes in the expression of hormone receptors and proteins related to apoptosis and proliferation by immunohistochemistry and Western Blot.

RESULTS

In vivo, hypothyroidism retards mammary carcinogenesis but its treatment with T₄ reverted the protective effects. In vitro, the proliferative and anti-apoptosis mechanisms of T₄ were different regarding the thyroid status. In EUT tumors, the main signaling pathway involved was the cross-talk with other receptors, such as ERα, PgR, and HER2. In HypoT tumors, the non-genomic signaling pathway of T₄ was the chief mechanism involved since αvβ3 integrin, HER2, β-catenin and, downstream, PI3K/AKT and ERK signaling pathways were activated.

CONCLUSION

T₄ can regulate mammary carcinogenesis by mainly activating its non-genomic signaling pathway and by interacting with other hormone or growth factor pathways endorsing that overdoses of thyroid replacement therapy with T4 can increase the risk of breast cancer.

Hypothyroidism affect progression and worse outcomes of breast cancer but not ovarian cancer

Some studies suggest that thyroid hormones and disorders can influence breast (BC) and ovarian (OC) cancers risks. However, studies regarding their effect on these tumors progression are limited. Thyroid-stimulating hormone (TSH), T4, free T4 (FT4), T3, and free T3 (FT3) were detected in patients with BC, OC, benign breast and ovary diseases, and healthy controls using highly sensitive chemiluminescence assay. In contrast to OC, hypothyroidism prevalence was associated with BC late stage (11/24 vs. 2/46), high grade (11/23 vs. 4/47), lymph node invasion (11/42 vs. 0/28), positive distant metastasis (11/25 vs. 1/45), and large tumor size (14/25 vs. 1/45) compared to tumor early stages, low grades, negative lymph node, and distant metastasis and small size, respectively. Patients with late stage, high grade, large tumor size, positive lymph nodes, or positive distant metastasis were significantly (P < 0.05) associated with elevated levels of TSH and decreased levels of T4, FT4, T3, and FT3. There were both significant positive correlation of serum TSH and significant inverse correlation of T4, FT4, T3, and FT3 with these tumor worse outcomes. In conclusion, our results identify hypothyroidism as potentially important prognostic factor in BC not in OC that is associated with poor outcomes of BC patients.

Endocrine regulation of cancer stem cell compartments in breast tumors

Cancer cells within breast tumors exist within a hierarchy in which only a small and rare subset of cells is able to regenerate growths with the heterogeneity of the original tumor. These highly malignant cancer cells, which behave like stem cells for new cancers and are called "cancer stem cells" or CSCs, have also been shown to possess increased resistance to therapeutics, and represent the root cause underlying therapy failures, persistence of residual disease, and relapse. As >90% of cancer deaths are due to refractory tumors, identification of critical molecular drivers of the CSC-state would reveal vulnerabilities that can be leveraged in designing therapeutics that eradicate advanced disease and improve patient survival outcomes. An expanding and complex body of work has now described the exquisite susceptibility of CSC pools to the regulatory influences of local and systemic hormones. Indeed, breast CSCs express a plethora of hormonal receptors, which funnel hormonal influences over every aspect of breast neoplasia - be it tumor onset, growth, survival, invasion, metastasis, or therapy resistance - via directly impacting CSC behavior. This article is intended to shed light on this active area of investigation by attempting to provide a systematic and comprehensive overview of the available evidence directly linking hormones to breast CSC biology.

Thyroid dysfunctions and autoimmunity in breast cancer patients: a prospective case-control study

OBJECTIVE

The relationship of thyroid dysfunction and autoimmunity with breast cancer (BC) continues to be contentious. The primary aim of this study was to estimate the prevalence of thyroid dysfunctions and autoimmunity in BC patients, and the secondary aims were to investigate the relationship of thyroid dysfunction with the clinicopathological profile of and therapy received by BC patients.

METHODS

This was a single-center prospective case-control study (March 2015-May 2017). Women with BC (n = 191), age-matched healthy controls (n = 166) and malignant controls (patients with cervical cancer, n = 87) were enrolled. Basal serum free thyroxin (fT4), thyrotropin (TSH) and anti-thyroid peroxidase (TPO) antibody levels were measured in all three groups; fT4, TSH and TPO measures were repeated after chemotherapy and at the 1-year follow-up (one year after diagnosis) in the BC patients.

RESULTS

The prevalence of overall hypothyroidism and autoimmunity (p = 0.106) did not differ significantly between the three groups, but the rate of clinical hypothyroidism was significantly higher in the BC group than in the healthy control group and the malignant control group (12.2% vs. 3.0% vs. 4.6%, respectively; p = 0.001). BC patients had significantly lower mean basal TSH concentrations than the healthy controls (p = 0.017). The postchemotherapy TSH concentrations were significantly lower (p = 0.001), and the fT4 concentrations were higher, albeit not significantly (p = 1.00), than the respective basal concentrations. The reverse was true for the follow-up values, in which the TSH (p = 1.00) values were higher and the fT4 (p = 0.03) concentrations were lower than the respective basal concentrations. An additional 6% of the BC patients developed clinical hypothyroidism during follow-up. Hypothyroid (p = 0.02) and TPO-positive (p = 0.004) patients had significantly smaller tumors, but their other clinicopathological features were comparable to those without thyroid dysfunction.

CONCLUSION

The prevalence of clinical hypothyroidism requiring thyroxine replacement was significantly high in BC patients and increased further during follow-up. Hence, BC patients should be considered a high-risk group that should receive routine screening for hypothyroidism.

Thyroid disease is associated with an increased risk of breast cancer: a systematic review and meta-analysis

BACKGROUND

This study investigated the relationship between thyroid diseases and the risk of breast cancer (BC). Clarifying this issue can help medical staff perform of early prevention, diagnosis and treatment for breast cancer patients.

METHODS

The meta-analysis combined data from cohort studies and case-control to obtain a comprehensive result of the relationship between thyroid diseases and risk of BC. We comprehensively searched PubMed, EMbase, Web of Science, and the Cochrane Library. The search period was from the establishment of the databases to August 2020. Literature was collected and screened individually by two reviewers. There was English language restriction on the search and unpublished literature was excluded. The Newcastle-Ottawa Scale (NOS) was used to evaluate the quality of the selected studies prior to data extraction. The data collected included country, author, year of publication, research type, and number of cases. In cases where the data and study heterogeneity permitted, meta-analyses were performed, and odd ratios (ORs) with corresponding 95% confidence intervals (CIs) were calculated. Data were analyzed using the STATA 15.1 software.

RESULTS

A total of 21 articles were included in this study. Hyperthyroidism, thyroid cancer, thyroglobulin antibody (TGAb) levels, and thyroid microsomal antibody (TPOAb) levels were all significantly associated with an increased risk of BC, while hypothyroidism was associated with a reduced risk of BC.

CONCLUSIONS

This study demonstrated that hyperthyroidism, autoimmune thyroiditis (AITD), and thyroid cancer are significantly associated with an increased risk of BC, while hypothyroidism is associated with a reduced risk of BC.

Subclinical hypothyroidism and the risk of cancer incidence and cancer mortality: a systematic review

BACKGROUND

Thyroid hormone has been shown to be involved in carcinogenesis via its effects on cell proliferation pathways. The objective of this study is to determine the association between subclinical hypothyroidism (SCH) and the risk of incident cancer and cancer mortality via systematic review.

METHODS

A systematic search was performed on Medline and Pubmed to identify relevant studies. Randomized controlled trials, and observational studies assessing SCH or its treatment and the risk of incident cancer or cancer mortality were identified.

RESULTS

A total of 7 cohort and 2 case-control studies met our inclusion criteria. In general, these studies were of medium to good quality. Overall, studies revealed no association between SCH and breast and prostate cancer. One study found that untreated SCH may be associated with an increased risk of colorectal cancer (adjusted odds ratio [OR]: 1.16; 95% confidence interval [CI]: 1.08-1.24). One study showed an increased risk in thyroid cancer incidence (adjusted OR: 3.38; 95% CI: 2.05-5.59) associated with elevation of a thyroid stimulating hormone (TSH) of > 1.64mIU/L. Two studies found an increase in cancer mortality among patients with SCH compared to euthyroid individuals; in contrast one study found no association between subclinical hypothyroidism and cancer mortality among aging men.

CONCLUSION

The number of studies examining thyroid dysfunction and cancer risk and mortality is limited. Future studies assessing the association between thyroid dysfunction and cancer risk and mortality are needed, which will further address the need to treat subclinical hypothyroidism.

Risk of second primary breast cancer among cancer survivors: Implications for prevention and screening practice

Second primary breast cancer (SPBC) is becoming one of the major obstacles to breast cancer (BC) control. This study was aimed to determine the trend of SPBC incidence over time and the risk of developing SPBC in site-specific primary cancer survivors in the United States. The Surveillance, Epidemiology, and End Results (SEER) 13 registry (1992-2015) was used to identify SPBC patients with previous malignancies. Standardized incidence ratio (SIR) was computed to compare the incidence rates of the observed cases of SPBC in cancer survivors over the expected cases in the general population. Elevated risk of SPBC was observed in women with previous BC (SIR = 1.74) or thyroid cancer (SIR = 1.17). Women with initial skin melanoma in older age (≥50 years) (SIR = 1.11), or White race (SIR = 1.11) presented an elevated incidence of SPBC than the general female population. Besides, Asian/Pacific Islander (API) women with cancer of corpus uteri, ovary, bladder, or kidney were prone to developing SPBC when compared with the general population, with SIRs of 1.61, 1.35, 1.48, and 1.70, respectively. Male BC patients showed profound risk of developing SPBC (SIR = 34.86). Male leukemia patients also presented elevated risk of developing SPBC (SIR = 2.06). Our study suggests significant increase of SPBC in both sexes in the United States. Elevated risk of SPBC exists in survivors with primary BC, female thyroid cancer, male leukemia, and API female cancer patients with primary genitourinary cancer. Our study is helpful in developing strategies for BC control and prevention on specific first primary cancer survivors with an elevated risk of SPBC.

Breast cancer populations may have an increased prevalence of thyroglobulin antibody and thyroid peroxidase antibody: a systematic review and meta-analysis

PURPOSE

Thyroid autoimmunity might be in relation to other autoimmune endocrine disease or non-endocrine disorders and there are innate and adaptive immune cells in breast cancer. Because autoimmune factors are common characteristics of both thyroid autoimmunity and breast cancer, these two types of diseases may occur concurrently in certain patients. The chief goal of this meta-analysis is to perform a combined analysis of the raw data from all included studies, and thereby obtain a reliable conclusion concerning whether TgAb or TPOAb positivity and breast cancer are indeed correlated.

METHODS

To determine whether a correlation exists between TgAb or TPOAb positivity and breast cancer, this study performed a review of the literature that began by searching for articles in Chinese or English from the Medline, Embase, Web of Science core, Wanfang, Weipu and SinoMed databases, published during the time span extending from January 1980 to December 2017. On the basis of these raw data, we calculated odds ratio (OR) values, 95% confidence interval (CI) values, and P values.

RESULTS

A total of 11 studies were included in this study. By combining the raw data from the retrieved studies, we were able to perform a meta-analysis. The results of this meta-analysis support the hypothesis that patients with breast cancer have a higher TgAb or TPOAb positive rate than the non-breast disease control group (TgAb: OR = 2.71, 95% CI = 1.81-4.05, P < 0.001; TPOAb: OR = 2.86, 95% CI = 2.17-3.77, P < 0.001, respectively). Testing for publication bias indicated that no significant publication bias was present in this meta-analysis, and sensitivity analysis indicated that the results of analysis were stable and reliable.

CONCLUSIONS

The results of this meta-analysis suggest strongly that, the TgAb or TPOAb positive rate among patients with breast cancer should be higher than among the non-breast disease control group.

Breast Cancer Risk in Postmenopausal Women with Medical History of Thyroid Disorder in the Women's Health Initiative

Background: The association between thyroid disorders and breast cancer remains controversial, in part, due to small cohort sizes and inconsistent findings. We investigated this association in postmenopausal women to determine whether hyper- or hypothyroidism is associated with the risk of developing breast cancer and to determine whether menopausal hormone therapy (MHT) further modifies the risk. Methods: We conducted a prospective cohort study of multiethnic U.S. postmenopausal women aged 50 to 79 years enrolled in both clinical trial and observational study arms between 1993 and 1998 and followed up through February 28, 2017. Development of invasive breast cancer after enrollment was recorded and a history of hyper- or hypothyroidism before the diagnosis of breast cancer was identified. The effect modification by MHT in both study arms was analyzed. All statistical tests were two sided. Results: Among a total of 134,122 women who were included in our study, 8137 participants developed invasive breast cancer during the follow-up period. There was a significant inverse association of invasive breast cancer among women with a history of hypothyroidism (hazard ratio [HR] 0.91, confidence interval [95% CI] 0.86-0.97) and among women who had taken levothyroxine [HR 0.89, 95% CI 0.82-0.96]. Evaluating effect modification by MHT use, the inverse association between hypothyroidism treated with thyroid replacement medications and breast cancer risk was strongest in non-MHT users [HR 0.80, 95% CI 0.69-0.93]. The results did not significantly differ by race/ethnicity. Although a history of hyperthyroidism was associated with an increased risk of invasive breast cancer [HR 1.11, 95% CI 0.91-1.35], this finding did not reach statistical significance. We did not see significant differences in the breast cancer Surveillance, Epidemiology, and End Results stages, histologic types, morphologic grades, or receptor status (estrogen receptor, progesterone receptor, human epidermal growth factor receptor 2) according to thyroid disorder status. Conclusions: Compared with women with no history of thyroid disorder, hypothyroidism was associated with a lower risk of breast cancer. This was mainly seen among those who received thyroid replacement therapy and had never used MHT. Among the treatment options for hypothyroidism, levothyroxine had the strongest inverse association with breast cancer risk.

Molecular Functions of Thyroid Hormone Signaling in Regulation of Cancer Progression and Anti-Apoptosis

Several physiological processes, including cellular growth, embryonic development, differentiation, metabolism and proliferation, are modulated by genomic and nongenomic actions of thyroid hormones (TH). Several intracellular and extracellular candidate proteins are regulated by THs. 3,3,5-Triiodo-L-thyronine (T₃) can interact with nuclear thyroid hormone receptors (TR) to modulate transcriptional activities via thyroid hormone response elements (TRE) in the regulatory regions of target genes or bind receptor molecules showing no structural homology to TRs, such as the cell surface receptor site on integrin αvβ3. Additionally, L-thyroxine (T₄) binding to integrin αvβ3 is reported to induce gene expression through initiating non-genomic actions, further influencing angiogenesis and cell proliferation. Notably, thyroid hormones not only regulate the physiological processes of normal cells but also stimulate cancer cell proliferation via dysregulation of molecular and signaling pathways. Clinical hypothyroidism is associated with delayed cancer growth. Conversely, hyperthyroidism is correlated with cancer prevalence in various tumor types, including breast, thyroid, lung, brain, liver and colorectal cancer. In specific types of cancer, both nuclear thyroid hormone receptor isoforms and those on the extracellular domain of integrin αvβ3 are high risk factors and considered potential therapeutic targets. In addition, thyroid hormone analogs showing substantial thyromimetic activity, including triiodothyroacetic acid (Triac), an acetic acid metabolite of T₃, and tetraiodothyroacetic acid (Tetrac), a derivative of T₄, have been shown to reduce risk of cancer progression, enhance therapeutic effects and suppress cancer recurrence. Here, we have reviewed recent studies focusing on the roles of THs and TRs in five cancer types and further discussed the potential therapeutic applications and underlying molecular mechanisms of THs.

Tetrac as an anti-angiogenic agent in cancer

The thyroid hormones T3 and T4 have emerged as pro-angiogenic hormones with important implications for cancer management. Endogenous circulating hormone levels may help stimulate cancer progression and limit the effectiveness of anticancer therapy, though clinical data remain inconclusive. The capacity of thyroid hormones to modulate angiogenesis is mediated through non-canonical mechanisms initiated at the cell surface receptor integrin αvβ3. This integrin is predominantly expressed on tumour cells, proliferating endothelial cells and tumour stroma-associated cells, emphasising its potential relevance in angiogenesis and tumour biology. Thyroid hormone/integrin αvβ3 signalling results in the activation of intracellular pathways that are commonly associated with angiogenesis and are mediated through classical pro-angiogenic molecules such as vascular endothelial growth factor. The naturally occurring T4 analogue tetrac blocks the pro-angiogenic actions of thyroid hormones at the integrin receptor, in addition to agonist-independent anti-angiogenic effects. Tetrac reduces endothelial cell proliferation, migration and tube formation through a reduction in the transcription of vascular growth factors/growth factor receptors, hypoxia-inducible factor-1α, pro-angiogenic cytokines and a number of other pro-angiogenic genes, while at the same time stimulating the expression of endogenous angiogenesis inhibitors. It further modulates vascular growth factor activity by disrupting the crosstalk between integrin αvβ3 and adjacent growth factor receptors. Moreover, tetrac disrupts thyroid hormone-stimulated tumour recruitment, differentiation and the pro-angiogenic signalling of tumour stroma-associated mesenchymal stem cells. Tetrac affects tumour-associated angiogenesis via multiple mechanisms and interferes with other cancer cell survival pathways. In conjunction with its low toxicity and high tissue selectivity, tetrac is a promising candidate for clinical application.

Serum concentration of thyroid hormones in abnormal and euthyroid ranges and breast cancer risk: A cohort study

The impact of variations in serum thyroid hormone concentration within the euthyroid range on breast cancer risk remains unclear. We investigated the effect of serum thyrotropin (TSH) and thyroid hormone concentration on breast cancer risk. This cohort study involved 62,546 Korean women, aged ≥40 years, who were free of breast cancer at baseline and underwent health examination with determination of free thyroxine (FT4) and TSH. A parametric proportional hazard model was used to estimate the adjusted hazard ratio (aHR) and 95% confidence interval (CI). During a median follow-up of 4.8 years (interquartile range: 2.8-7.3 years), 834 incident breast cancers were identified. Compared to normal FT4 level, abnormally high serum FT4 level was associated with an increased risk of incident breast cancer with a corresponding multivariable aHR (95% CI) of 1.98 (1.02-3.83). This association tended to be stronger in postmenopausal women than in premenopausal women. Within the euthyroid range, the highest TSH tertile was associated with a lower risk of breast cancer than the lowest TSH tertile with a corresponding aHR (95% CI) of 0.68 (0.55-0.84). In contrast, highest FT4 tertile was associated with a higher risk of breast cancer than the lowest FT4 tertile. Abnormally high FT4 as well as higher FT4 within the euthyroid range were positively associated with breast cancer risk, while higher TSH concentration within the euthyroid range was negatively associated with breast cancer risk. Our findings indicate that thyroid function within both the abnormal and euthyroid ranges may contribute to the development of breast cancer.

Molecular Actions of Thyroid Hormone on Breast Cancer Cell Migration and Invasion via Cortactin/N-WASP

The thyroid hormone triiodothyronine (T3) plays a fundamental role in growth regulation, differentiation, metabolism and cellular movement. These processes are particularly important considering that deregulation of T3 levels could promote abnormal responsiveness of mammary epithelial cells, which may lead to the development and progression of breast cancer (BC). Once cells migrate and invade different tissues, BC metastasis is the main cause of cancer-related death because it is particularly difficult to revert this multistep process. Cell migration integrates several steps that induce changes in cell structure and morphology to promote BC cell invasion. These sequential steps include actin cytoskeleton remodeling, focal adhesion complex formation and, finally, the turnover of branched actin filament networks. In this article, we demonstrate that T3 has the ability to modify the Epithelial-Mesenchymal Transition process. In addition, we show that T3 induces actin cytoskeleton reorganization, triggers focal adhesion formation and, as a consequence, promotes actin nucleation via non-genomic pathway. These events are specifically modulated by T3 via integrin αvβ3 to FAK/paxillin/cortactin/N-WASP/Arp2/3 complex signaling pathway, increasing cell adhesion, migration and invasion of T-47D BC cells. We suggest that T3 influences the progression of tumor metastasis by controlling signaling pathways that converge in cell motility. This knowledge is crucial for the development of novel therapeutic strategies for BC treatment.

Clinical Implications and Impact of Discovery of the Thyroid Hormone Receptor on Integrin αvβ3-A Review

Hypothyroidism has been reported to improve survival in cancer patients but only recently has the putative mechanism been identified as a receptor for thyroxine and tri-iodothyronine on integrin αvβ3. Recognition of divergence of action of the pro-oncogenic L-thyroxine (T4) from pro-metabolic 3,5,3'-triiodo-L-thyronine (T3) has enabled clinical implementation whereby exogenous T3 may replace exogenous (or endogenous) T4 to maintain clinical euthyroid hypothyroxinemia that results in significantly better survival in advanced cancer patients without the morbidity of clinical hypothyroidism.

Thyroid Hormones and Cancer: A Comprehensive Review of Preclinical and Clinical Studies

Thyroid hormones take major part in normal growth, development and metabolism. Over a century of research has supported a relationship between thyroid hormones and the pathophysiology of various cancer types. In vitro studies as well as research in animal models demonstrated an effect of the thyroid hormones T3 and T4 on cancer proliferation, apoptosis, invasiveness and angiogenesis. Thyroid hormones mediate their effects on the cancer cell through several non-genomic pathways including activation of the plasma membrane receptor integrin αvβ3. Furthermore, cancer development and progression are affected by dysregulation of local bioavailability of thyroid hormones. Case-control and population-based studies provide conflicting results regarding the association between thyroid hormones and cancer. However, a large body of evidence suggests that subclinical and clinical hyperthyroidism increase the risk of several solid malignancies while hypothyroidism may reduce aggressiveness or delay the onset of cancer. Additional support is provided from studies in which dysregulation of the thyroid hormone axis secondary to cancer treatment or thyroid hormone supplementation was shown to affect cancer outcomes. Recent preclinical and clinical studies in various cancer types have further shown promising outcomes following chemical reduction of thyroid hormones or inhibition or their binding to the integrin receptor. This review provides a comprehensive overview of the preclinical and clinical research conducted so far.

Triiodothyronine Promotes Cell Proliferation of Breast Cancer via Modulating miR-204/Amphiregulin

Breast cancer (BC) severely threatens women's life, and Triiodothyronine (T3) shows a positive role on BC cell proliferation, while the potential mechanism underlying it is still unclear. T3 was used to stimulate BC cell lines MCF-7 and T47-D. Real-time PCR was performed to determine the expression of miRNAs, while western blot was used to measure protein expression of Amphiregulin (AREG), AKT and p-AKT. The interaction between miR-204 and AREG was determined using luciferase reporter assay. MTT was performed to detect cell viability. The expression of miR-204 was decreased, while AREG and p-AKT was increased in T3 stimulated BC cell lines. T3 stimulation promoted cell viability. miR-204 targets AREG to regulate its expression. T3 promoted expression of AREG and p-AKT, while miR-204 overexpression reversed the effect of T3, however, pcDNA-AREG transfection abolished the effect of miR-204 mimic. T3 promoted cell viability of BC cells via modulating the AKT signaling pathway. The detailed mechanism was that the down-regulated miR-204 that induced by T3 stimulation promoted the expression of AREG, the up-regulated AREG activated AKT signaling pathway, while the activated AKT signaling promoted cell proliferation.

Review of the possible association between thyroid and breast carcinoma

Background

Thyroid and breast cancer are two of the malignant diseases with highest incidence in females. Based on clinical experience, breast and thyroid cancer often occur metachronously or synchronously. Therefore, thyroid and breast cancer might share some common etiological factors. The relationship between these diseases has attracted substantial attention, and because these two glands are both regulated by the hypothalamic-pituitary axis, such a relationship is not surprising. A study of this relationship will be useful for obtaining a better understanding of the mechanism by which these two malignancies co-occur.

Main body

This study reviewed the progress in research on the roles of iodine intake, folate metabolism, obesity, gonadal hormones, and thyroid hormone in thyroid and breast cancer. These studies evaluating the etiological roles of these factors in linking breast and thyroid cancer might also improve our understanding and identify new therapeutic approaches, such as sodium/iodide symporter-mediated radioiodine therapy and thyroid-stimulating hormone receptor antagonists, for breast cancer. In addition, some specific treatments for each cancer, such as radiotherapy for breast cancer or radioactive iodine therapy for thyroid cancer, might be risk factors for secondary malignances, including breast and thyroid cancer.

Conclusions

Studies of the precise relationship between the co-occurrence of breast and thyroid cancer will certainly improve our understanding of the biological behaviors of these two malignancies and direct evidence-based clinical practice.

[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.

Does thyroid dysfunction increase the risk of breast cancer? A systematic review and meta-analysis

PURPOSE

To investigate the relationship between hypothyroidism, hyperthyroidism, thyroid hormone replacement, and the risk of breast cancer.

METHODS

We searched the PubMed, Cochrane Library, EMbase, Web of Science, and China Biology Medicine (CBM) databases through June 2016 to identify researches that assessed the relationship between thyroid dysfunction and the risk of breast cancer together with the impact of thyroid hormone substitution treatment on incidence of breast cancer. Quality of evidence was assessed per outcome, using GRADE.

RESULTS

A total of 13 population-based studies including 24,808 participants were identified as eligible for this meta-analysis. A meta-analysis of 12 researches illustrated that hypothyroidism was not related to the risk for breast cancer [odds ratio (OR) = 0.83, 95% confidence interval (CI) 0.64-1.08, P = 0.162]. 10 researches illustrated that hyperthyroidism was also not related to the risk of breast cancer (OR = 1.03, 95% CI 0.83-1.30, P = 0.767). The impact of therapy was evaluated in six researches; there was no proof of a relationship between thyroid hormone substitution treatment and breast cancer with an overall OR of 0.83 (95% CI 0.57-1.21, P = 0.965).

CONCLUSIONS

Our meta-analysis illustrated that thyroid dysfunction may not be related to increased risk of breast cancer as well as the thyroid hormone substitution treatment did not reduce the incidence of breast cancer; while this study has some confounders that might weaken the results of this meta-analysis, we believe that the findings provide valuable information for stakeholders concerned with outcomes in patients with thyroid dysfunction.

Thyroid Function and Cancer Risk: The Rotterdam Study

CONTEXT

In vitro and in vivo experiments have assigned both oncosuppressive and oncogenic properties to thyroid hormones. Population-based studies have found inconclusive results.

OBJECTIVE

We aimed to prospectively assess the relation between thyroid function and incident cancer in a population-based setting.

DESIGN, SETTING, AND PARTICIPANTS

The current study is a prospective population-based cohort study including 10 318 participants for whom baseline measurements of free T₄ (FT₄) and/or TSH were available.

MAIN OUTCOME MEASURES

Cox proportional hazards models were used to assess hazard ratios (HRs) of any solid non-skin cancer, as well as lung, breast, prostate, and gastrointestinal cancer specifically.

RESULTS

Higher FT₄ levels were associated with a higher risk of any solid cancer (HR, 1.42; 95% confidence interval [CI], 1.12-1.79), lung cancer (HR, 2.33; 95% CI, 1.39-3.92) and breast (HR, 1.77; 95% CI, 1.10-2.84) cancer. The risk estimates were similar after exclusion of thyroid-altering medication, but the association lost significance for breast cancer. Compared with the lowest FT₄ tertile, the highest tertile was associated with a 1.13-fold increased risk of any solid, 1.79-fold increased risk of lung, and 1.14-fold increased risk of breast cancer (P for trend <.05 for all). For TSH levels we found no associations with cancer risk. There was no differential effect of sex or age on the association between thyroid function and cancer risk.

CONCLUSIONS

Higher FT₄ levels are significantly associated with an increased risk of any solid, lung, and breast cancer. Further research should elucidate the underlying pathophysiological mechanisms.

Effect of Thyroid Function on MNU-Induced Mammary Carcinogenesis

Mammary cancer is a disease that affects many women. Extensive research has been conducted to elucidate which variables are involved in the development of this cancer. Studies have highlighted thyroid function as a modulator of tumor growth and development. Thyroxine and 3,3',5-triiodothyronine are responsible for regulating the development, differentiation, homeostasis, and metabolism of cells in the body including mammary tissue. Thyroid hormones also have estrogen-like effects on mammary cancer cell growth by regulating the estrogen receptor. The present study was designed to determine whether medically induced hyperthyroidism increases the multiplicity, prevalence, and mammary tumor burden in rats; and to elucidate whether surgically induced hypothyroidism conversely attenuates the rate of mammary cancer cell growth. Female Sprague-Dawley rats were randomly divided into three groups (euthyroid-control, hyperthyroid, and hypothyroid). Hyperthyroidism was induced via oral administration of levothyroxine; whereas, hypothyroidism was induced by thyroidectomy. Mammary carcinogenesis was induced with a single intraperitoneal injection of N-methyl-N-nitrosurea (MNU). Rats were sacrificed at 38 weeks, and the mammary tumors were excised, fixed for histology and analyzed. Analysis included evaluation of malignancy and immunohistochemistry for ER. MNU-induced mammary carcinogenesis among the groups resulted in a significant difference in tumor burden. The hyperthyroid group had a statistically higher tumor burden than did the euthyroid group, and the hypothyroid group had no tumors of mammary tissue origin at 38 weeks. All excised mammary tumors were ER alpha negative. These data support the hypothesis that thyroid function is one of potentially many factors that contribute to modulation of MNU-induced mammary tumor growth.

STUDY OF THE PREVALENCE OF AUTOIMMUNE THYROID DISEASE IN WOMEN WITH BREAST CANCER

OBJECTIVE

The aim of this study was to analyze the prevalence of thyroid disorders in patients with a positive biopsy for breast cancer prior to specific antitumor treatment.

METHODS

The frequency and pattern of thyroid disorders were evaluated in 112 patients with breast cancer (G1) and 125 control patients (G2) by analyzing serum thyroid-stimulating hormone (TSH), anti-thyroid peroxidase antibodies, and anti-thyroglobulin antibodies. In addition, the expression of estrogen receptors, progesterone receptors, and human epidermal growth factor receptor 2 (HER2) was assessed in the breast biopsies by immunohistochemistry.

RESULTS

The frequency of thyroid disorders, such as changes in TSH levels and/or the presence of thyroid antibodies, was not different between the 2 groups examined (30.4% in G1 versus 28.0% in G2) (P = .69). However, a family history of thyroid disease was more frequent in patients with breast cancer (50.5% in G1 versus 28.2% in G2) (P = .001). Regarding the clinical stage of breast cancer, there was no difference between women with autoimmune thyroiditis and those without thyroid dysfunction (P = .316). Similarly, there were no differences in hormone receptor (estrogen or progesterone) and HER2 expression between patients who tested positive and those who tested negative for anti-thyroid antibodies (P = .052 and P = .549, respectively).

CONCLUSION

The data obtained in this study did not reveal a higher frequency of autoimmune thyroid disease in patients with breast cancer compared to controls. A family history of thyroid disease was more common in those with breast cancer.

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.

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.

Comparative Study of Alterations in Tri-iodothyronine (T3) and Thyroxine (T4) Hormone Levels in Breast and Ovarian Cancer

Objective : The present study was designed to investigate variations in the levels of thyroid hormones (T3, T4) in breast and ovarian cancers patients. Methods : A total 120 subjects were recruited (without thyroid history) divided into three groups; A, B and C. Group A as control with healthy individuals. While group B and group C were consisting of breast cancer and ovarian cancer patient respectively. Blood samples (5 ml) were taken and analyzed to estimate the levels of serum T3 (tri-iodothyronine) and T4 (thyroxin) hormones. R esults : Statistically significant difference (P=0.000* and P=0.017*) was obtained among all groups. A significant increase in T3 (P=0.000*) and T4 (0.005*) levels was observed among breast cancer patients as compared to healthy controls. While for ovarian cancer patients conflicting results were found for T3 and T4 levels in the serum i.e. insignificant difference was found in T3 (P=0.209) and T4 (P=0.050) as compared to control. Our results showed that in the breast cancer and ovarian cancer patients the thyroid hormone (T3 and T4) level has been altered from the normal ranges as compared to the normal healthy individuals. Conclusion : We conclude that hyperthyroidism has profound effects on breast cancer and ovarian cancer cells proliferation.

Triiodothyronine and breast cancer

The thyroid hormones (THs), triiodothyronine (T3) and thyroxine (T4), are essential for survival; they are involved in the processes of development, growth, and metabolism. In addition to hyperthyroidism or hypothyroidism, THs are involved in other diseases. The role of THs in the development and differentiation of mammary epithelium is well established; however, their specific role in the pathogenesis of breast cancer (BC) is controversial. Steroid hormones affect many human cancers and the abnormal responsiveness of the mammary epithelial cells to estradiol (E2) in particular is known to be an important cause for the development and progression of BC. The proliferative effect of T3 has been demonstrated in various types of cancer. In BC cell lines, T3 may foster the conditions for tumor proliferation and increase the effect of cell proliferation by E2; thus, T3 may play a role in the development and progression of BC. Studies show that T3 has effects similar to E2 in BC cell lines. Despite controversy regarding the relationship between thyroid disturbances and the incidence of BC, studies show that thyroid status may influence the development of tumor, proliferation and metastasis.

T3 levels in relation to prognostic factors in breast cancer: a population-based prospective cohort study

BACKGROUND

The issue of a potential association between thyroid conditions/hormones and breast cancer has been studied extensively during the last decades but the results have been inconclusive and almost no studies have investigated breast cancer aggressiveness. We have previously found a positive association between prospectively measured levels of triiodothyronine (T3) and breast cancer incidence as well as breast cancer mortality. We now investigated prediagnostic T3 levels in relation to specific prognostic factors in breast cancer.

METHODS

The Malmö Preventive Project is a population-based prospective cohort including 2185 women in whom T3 levels were measured at baseline. That is, total T3 levels were measured before a potential diagnosis of breast cancer. Mean follow-up was 23.3 years and 149 women in the study population were diagnosed with invasive breast cancer. Tumours were classified according to selected prognostic factors of breast cancer; i.e. grade, tumour size, lymph node metastasis, and hormonal receptor status. T3 was handled both as tertiles and as a continuous variable. A Cox's proportional hazards analysis yielded hazard ratios with 95% confidence intervals. All analyses were also restricted to postmenopausal women.

RESULTS

Overall there was a statistically significant association between T3 and "all" breast cancers. The adjusted Hazard Ratio (HR) in the third tertile, as compared to the first, was (1.61:1.07-2.43). There was a statistically significant positive association between the third T3 tertile and large tumours, i.e. > 20 mm, (3.17:1.20-8.36) and the occurrence of lymph node metastases, (4.53:1.60-12.83). Other prognostic factors positively associated with T3 were negative oestrogen receptor (ER) status, (3.52:1.32-9.41) and negative progesterone receptor (PGR) status, (3.52:1.42-8.75). The analyses of T3 as a continuous variable and analysis restricted to postmenopausal women, confirmed the results but also showed an association with smaller tumours and in postmenopausal women a contemporary association with negative lymph nodes.

CONCLUSIONS

This prospective study of serum T3 levels in relation to breast cancer aggressiveness is the first of its kind. We found statistically significant positive associations between higher prediagnostic T3 levels and larger tumours, occurrence of lymph node metastases, and negative ER and PGR status.

Thyroid hormone status interferes with estrogen target gene expression in breast cancer samples in menopausal women

We investigated thyroid hormone levels in menopausal BrC patients and verified the action of triiodothyronine on genes regulated by estrogen and by triiodothyronine itself in BrC tissues. We selected 15 postmenopausal BrC patients and a control group of 18 postmenopausal women without BrC. We measured serum TPO-AB, TSH, FT4, and estradiol, before and after surgery, and used immunohistochemistry to examine estrogen and progesterone receptors. BrC primary tissue cultures received the following treatments: ethanol, triiodothyronine, triiodothyronine plus 4-hydroxytamoxifen, 4-hydroxytamoxifen, estrogen, or estrogen plus 4-hydroxytamoxifen. Genes regulated by estrogen (TGFA, TGFB1, and PGR) and by triiodothyronine (TNFRSF9, BMP-6, and THRA) in vitro were evaluated. TSH levels in BrC patients did not differ from those of the control group (1.34 ± 0.60 versus 2.41 ± 1.10 μU/mL), but FT4 levels of BrC patients were statistically higher than controls (1.78 ± 0.20 versus 0.95 ± 0.16 ng/dL). TGFA was upregulated and downregulated after estrogen and triiodothyronine treatment, respectively. Triiodothyronine increased PGR expression; however 4-hydroxytamoxifen did not block triiodothyronine action on PGR expression. 4-Hydroxytamoxifen, alone or associated with triiodothyronine, modulated gene expression of TNFRSF9, BMP-6, and THRA, similar to triiodothyronine treatment. Thus, our work highlights the importance of thyroid hormone status evaluation and its ability to interfere with estrogen target gene expression in BrC samples in menopausal women.

Estrogen-responsive genes overlap with triiodothyronine-responsive genes in a breast carcinoma cell line

It has been well established that estrogen plays an important role in the progression and treatment of breast cancer. However, the role of triiodothyronine (T₃) remains controversial. We have previously shown its capacity to stimulate the development of positive estrogen receptor breast carcinoma, induce the expression of genes (PR, TGF-alpha) normally stimulated by estradiol (E₂), and suppress genes (TGF-beta) normally inhibited by E₂. Since T₃ regulates growth hormones, metabolism, and differentiation, it is important to verify its action on other genes normally induced by E₂. Therefore, we used DNA microarrays to compare gene expression patterns in MCF-7 breast adenocarcinoma cells treated with E₂ and T₃. Several genes were modulated by both E₂ and T₃ in MCF-7 cells (Student's t-test, P < 0.05). Specifically, we found eight genes that were differentially expressed after treatment with both E₂ and T₃, including amphiregulin, fibulin 1, claudin 6, pericentriolar material 1, premature ovarian failure 1B, factor for adipocyte differentiation-104, sterile alpha motif domain containing 9, and likely ortholog of rat vacuole membrane protein 1 (fold change > 2.0, pFDR < 0.05). We confirmed our microarray results by real-time PCR. Our findings reveal that certain genes in MCF-7 cells can be regulated by both E₂ and T₃.

Pregnancy-associated breast cancers are driven by differences in adipose stromal cells present during lactation

INTRODUCTION

The prognosis of breast cancer is strongly influenced by the developmental stage of the breast when the tumor is diagnosed. Pregnancy-associated breast cancers (PABCs), cancers diagnosed during pregnancy, lactation, or in the first postpartum year, are typically found at an advanced stage, are more aggressive and have a poorer prognosis. Although the systemic and microenvironmental changes that occur during post-partum involution have been best recognized for their role in the pathogenesis of PABCs, epidemiological data indicate that PABCs diagnosed during lactation have an overall poorer prognosis than those diagnosed during involution. Thus, the physiologic and/or biological events during lactation may have a significant and unrecognized role in the pathobiology of PABCs.

METHODS

Syngeneic in vivo mouse models of PABC were used to examine the effects of system and stromal factors during pregnancy, lactation and involution on mammary tumorigenesis. Mammary adipose stromal cell (ASC) populations were isolated from mammary glands and examined by using a combination of in vitro and in vivo functional assays, gene expression analysis, and molecular and cellular assays. Specific findings were further investigated by immunohistochemistry in mammary glands of mice as well as in functional studies using ASCs from lactating mammary glands. Additional findings were further investigated using human clinical samples, human stromal cells and using in vivo xenograft assays.

RESULTS

ASCs present during lactation (ASC-Ls), but not during other mammary developmental stages, promote the growth of carcinoma cells and angiogenesis. ASCs-Ls are distinguished by their elevated expression of cellular retinoic acid binding protein-1 (crabp1), which regulates their ability to retain lipid. Human breast carcinoma-associated fibroblasts (CAFs) exhibit traits of ASC-Ls and express crabp1. Inhibition of crabp1in CAFs or in ASC-Ls abolished their tumor-promoting activity and also restored their ability to accumulate lipid.

CONCLUSIONS

These findings imply that (1) PABC is a complex disease, which likely has different etiologies when diagnosed during different stages of pregnancy; (2) both systemic and local factors are important for the pathobiology of PABCs; and (3) the stromal changes during lactation play a distinct and important role in the etiology and pathogenesis of PABCs that differ from those during post-lactational involution.

A large cohort study of hypothyroidism and hyperthyroidism in relation to gynecologic cancers

Background. Thyroid status may influence tumorigenesis of gynecologic cancers, yet epidemiologic studies of this relationship are limited and inconsistent. Methods. We evaluated the association of self-reported history of physician-diagnosed hypothyroidism and hyperthyroidism with medical-record confirmed endometrial (EC; all invasive adenocarcinomas) and ovarian cancer (OC; epithelial ovarian or peritoneal cancers) in Nurses' Health Study (NHS) from 1976 to 2010 and NHSII from 1989 to 2011. Cox proportional hazard models were used to estimate multivariable rate ratios (RRs) and 95% confidence intervals based on pooled cohort data. Results. We confirmed 1314 incident cases of EC and 1150 cases of OC. Neither a history of hypothyroidism nor hyperthyroidism was significantly associated with risk of EC or OC. However, having a history of hypothyroidism for 8+ years (median) was nonsignificantly inversely associated with EC (RR = 0.81; 95% CI = 0.63-1.04; P-trend with history duration = 0.11) and OC (RR = 0.87, 95% CI = 0.66-1.15; P-trend = 0.13). Having a history of hyperthyroidism for 6+ years (median) was non-significantly positively associated with EC (RR = 1.69; 95% CI = 0.86-3.30; P-trend = 0.12) but not OC (RR = 1.12; 95% CI = 0.46-2.72; P-trend = 0.95). Conclusions. A history of hypothyroidism or hyperthyroidism was not significantly associated with risk of EC or OC.

Cancer risk in patients with Graves' disease: a nationwide cohort study

BACKGROUND

The possibility of an association of Graves' disease (GD) with subsequent cancers has been previously reported.

METHODS

Our study used the Taiwanese National Health Insurance Research Database (NHIRD), which identified 5025 newly diagnosed GD patients from 1997 to 2010, and 20,100 frequency matched non-GD patients. The risk of developing cancer for GD patients was measured using the Cox proportional hazard model.

RESULTS

The incidence of developing cancer in the GD cohort was 4.92 per 1000 person-years and was 1.37-fold higher than in the comparison cohort (p<0.001). Compared with patients aged 20-34 years, older age groups demonstrated a higher risk of developing cancer (35-49 years: hazard ratio (HR)=4.15; 50-64 years: HR=7.39;≥65 years: HR=13.4). After adjusting for sex, age, and comorbidities, the HR for developing breast cancer and thyroid cancer was 1.58- and 10.4-fold higher for patients with GD. Furthermore, the incidence rates (IRR) were the highest in the first three years: 2.06 [confidence interval (CI)=1.87-2.27] and 15.6 [CI=13.9-17.5] in breast cancer and thyroid cancer with GD respectively. Specifically, a 16-fold hazard of developing thyroid cancer was present in the first three years in the GD cohort compared to the non-GD cohort [CI=7.95-32.1].

CONCLUSIONS

GD patients have a higher risk of cancer, particularly thyroid and breast cancer sequent within six and three years respectively. Strategies for preventing thyroid and breast cancer are proposed.

TSH receptor antibodies have predictive value for breast cancer - retrospective analysis

Background

Associations between breast cancer and thyroid disorders are reported in numerous studies. Relationships between thyroperoxidase antibodies (TPOAb), thyroglobulin antibodies (TgAb) and breast cancer have been previously demonstrated. However, no analysis has been performed concerning an association between thyrotropin (TSH) receptor antibodies (TSHRAb) and breast cancer. The aim of the study was to evaluate the prevalence of breast cancer or benign breast tumors in patients with Graves’ disease and to analyze a possible relationship between Graves’ disease and these two groups of breast diseases with emphasis to epidemiology and laboratory findings.

Patients and methods

Clinical and laboratory details of 2003 women hospitalized for endocrine disorders were retrospectively analyzed, using an unpaired Student’s t-test, logistic regression analysis, χ² test of independence or the two-sided ratio comparison test.

Results

The coexistence of Graves’ disease and breast cancer was statistically significant. We observed TSHRAb and TgAb more frequently in patients with breast cancer. We found that TSHRAb is the only variable possessing predictive value for breast cancer.

Conclusions

The strong relationship between Graves’ disease and breast cancer is proposed. We suggest that TSHRAb could be described as a positive determinant of breast cancer. The present data call attention to the usefulness of screening for breast cancer in long-term follow-up of patients with autoimmune thyroid disorders, especially of those with Graves’ disease. Similarly, screening for autoimmune thyroid disorders should be performed in patients with nodular breast disease. Additionally, the article draws ideas for further research in order to develop targeted treatment for more successful outcome in patients with breast cancer.

Triiodothyronine levels in relation to mortality from breast cancer and all causes: a population-based prospective cohort study

OBJECTIVE

The potential association between thyroid hormones and breast cancer has been investigated in a large number of studies without conclusive results. This study investigated triiodothyronine (T3) levels in relation to breast cancer mortality in a population with no breast cancer patients at baseline. An additional aim was to study T3 levels in relation to mortality from other cancers and all-cause mortality.

DESIGN AND METHODS

This was a population-based prospective cohort study including 2185 women in whom T3 levels were measured as part of a preventive health project, i.e. before diagnosis in women who later developed breast cancer. Mean follow-up was 24.1 years and record-linkage to The Swedish Cause-of-Death registry identified 471 women who died: 26 out of breast cancer and 182 from other cancers. Mortality was assessed using a Cox's analysis, yielding hazard ratios (HRs), with 95% confidence intervals. Analyses of T3 as a continuous variable were repeated for pre- and peri/postmenopausal women separately.

RESULTS

T3 levels were positively associated with the risk of breast cancer-specific death in the age-adjusted analysis: HR for T3 as a continuous variable was 2.80 (1.26-6.25). However, the crude analysis did not reach statistical significance. Breast cancer mortality was even higher in postmenopausal women: 3.73 (1.69-8.22), but stratified analyses included few events. There were no statistically significant associations between T3 levels and deaths from other cancers, age-adjusted HR: 1.09 (0.72-1.65) or all-cause mortality (1.25:0.97-1.60).

CONCLUSIONS

This study, the first of its kind on prospectively measured T3 levels, indicates that T3 levels are positively associated with breast cancer-specific mortality and that this is not related to a general effect on all-cause mortality.

Perfil dos hormônios da tireoide em pacientes com câncer de mama em estado de menopausa

OBJETIVO: Verificar o perfil dos hormônios tireóideos (HTs) em pacientes pós-menopausa portadoras de carcinoma de mama (CaM). SUJEITOS E MÉTODOS: Participaram 12 pacientes com CaM em estádio I ou II sem intervenções que pudessem interferir na progressão tumoral e um grupo controle com 18 pacientes em pós-menopausa sem CaM. Foram dosados os níveis séricos de anticorpo antitiroperoxidase (TPOAB), hormônio estimulante da tireoide (TSH), tiroxina livre (T4L), estradiol (E2), hormônio folículo estimulante (FSH) e hormônio luteinizante (LH) antes e após a cirurgia, e realizada a imunoistoquímica dos receptores de estrógeno (ER) e progesterona (PR). RESULTADOS: Quatro pacientes com CaM apresentaram alterações do perfil hormonal tireoidiano: dois hipertireoidismo, um hipotireoidismo e positividade TPO-AB, todas com ER e PR positivos. Os níveis de TSH dessas pacientes não foram diferentes dos níveis encontrados no grupo controle (1,89 ± 1,56 vs. 2,86 ± 3,12 mUI/mL), porém os níveis de T4L nas pacientes com CaM foram estatisticamente maiores que o controle (1,83 ± 0,57 vs. 1,10 ± 0,20 ng/dL). CONCLUSÃO: Esses resultados reforçam a necessidade de avaliação do status tireoidiano em pacientes com CaM, uma vez que, na ausência de E2, mudanças clínicas nos HTs podem atuar em vias controladas pelo E2.

Prospectively measured thyroid hormones and thyroid peroxidase antibodies in relation to breast cancer risk

Thyroid hormones influence both normal breast cell differentiation and breast cancer cell proliferation and stimulate the angiogenesis of certain cancer forms. Several cross-sectional studies have measured thyroid hormones/autoantibodies in breast cancer ceases vs. controls, but it is difficult to determine the cause-effect direction in these studies. Only three prospective studies have reported on the subject so far. The aim of our study was to investigate prediagnostically measured levels of thyroid hormones, thyrotropin (TSH) and thyroid autoantibodies in relation to subsequent risk of breast cancer. The Malmoe Diet and Cancer study examined 17,035 women between 1991 and 1996. Blood samples were collected at baseline and free triiodothyronine (T3), free thyroxin (T4), TSH and thyroid peroxidase autoantibodies (TPO-Ab) levels were measured in 676 cases and 680 controls. Relative risks with 95% confidence intervals were assessed using a logistic regression analysis adjusted for potential confounders. Free T4 levels were positively associated with a high risk of breast cancer, and the OR for women with free T4 levels above vs. below the median was 1.40 (1.10-1.77). This association was most pronounced in overweight women (1.51:1.07-2.12). Women with high levels of TPO-Ab had a lower risk of breast cancer, but only the analysis of TPO-Ab as a continuous variable reached statistical significance. Free T4 was in our study positively associated with a high risk of breast cancer. This association was most pronounced in overweight/obese women. Women with a high level of TPO-Ab had a relatively low risk of breast cancer.

Benign thyroid disease is associated with breast cancer: a meta-analysis

The controversial relationship between benign thyroid diseases and breast cancer (BC) has been investigated for over 50 years. Despite extensive population studies, the results as a whole have been inconsistent. The purpose of this study was to collate and analyse available data, calculating a pooled odds ratio (OR) of the risk of BC in patients diagnosed with benign thyroid diseases. Studies were obtained from a database search of MEDLINE, EMBASE, PubMed, Current Contents Connect and Google Scholar with additional cross checking of reference lists. Inclusion criteria required a confirmed diagnosis of a benign thyroid disease, reporting of an OR or data to calculate an OR (and 95% confidence interval, CI) and the use of an internal control group as the comparator. Collated data was assessed for heterogeneity and a pooled OR calculated. 28 studies were included in the meta-analysis. There was significant evidence of an increased risk of BC in patients with autoimmune thyroiditis, evident in a pooled OR 2.92 (95% CI 2.13-4.01). In addition, the results supported an increased risk associated with the presence of anti-thyroid antibodies (OR 2.02, 95% CI 1.63-2.50) and goitre (OR 2.26, 95% CI 1.39-3.69). Subgroup analysis of antibody presence revealed increased risk associated with both anti-TPO (OR 2.64, 95% CI 1.82-3.83) and anti-TG (2.71, 95% CI 1.58-4.69). Quantitative analysis of hypothyroidism and hyperthyroidism was not significant. While these results indicate an association between thyroid auto-immunity and BC, further prospective studies are required to definitively prove causality.

Mutation of thyroid hormone receptor-β in mice predisposes to the development of mammary tumors

Correlative data suggest that thyroid hormone receptor-β (TRβ) mutations could increase the risk of mammary tumor development, but unequivocal evidence is still lacking. To explore the role of TRβ mutants in vivo in breast tumor development and progression, we took advantage of a knock-in mouse model harboring a mutation in the Thrb gene encoding TRβ (Thrb(PV) mouse). Although in adult nulliparous females, a single ThrbPV allele did not contribute to mammary gland abnormalities, the presence of two ThrbPV alleles led to mammary hyperplasia in ∼36% Thrb(PV/PV) mice. The ThrbPV mutation further markedly augmented the risk of mammary hyperplasia in a mouse model with high susceptibility to mammary tumors (Pten(+/-) mouse), as demonstrated by the occurrence of mammary hyperplasia in ∼60% of Thrb(PV/+)Pten(+/-) and ∼77% of Thrb(PV/PV)Pten(+/-) mice versus ∼33% of Thrb(+/+)Pten(+/-) mice. The Thrb(PV) mutation increased the activity of signal transducer and activator of transcription (STAT5) to increase cell proliferation and the expression of the STAT5 target gene encoding β-casein in the mammary gland. We next sought to understand the molecular mechanism underlying STAT5 overactivation by TRβPV. Cell-based studies with a breast cancer cell line (T47D cells) showed that thyroid hormone (T3) repressed STAT5 signaling in TRβ-expressing cells through decreasing STAT5-mediated transcription activity and target gene expression, whereas sustained STAT5 signaling was observed in TRβPV-expressing cells. Collectively, these findings show for the first time that a TRβ mutation promotes the development of mammary hyperplasia via aberrant activation of STAT5, thereby conferring a fertile genetic ground for tumorigenesis.

Thyroid hormones and cancer: clinical studies of hypothyroidism in oncology

PURPOSE OF REVIEW

To collect and assess clinical reports of a putative relationship between thyroid state and the biology of cancers of various types.

RECENT FINDINGS

A number of prospective case-control studies reviewed here have suggested that subclinical hyperthyroidism increases risk of certain solid tumors and that spontaneous hypothyroidism may delay onset or reduce aggressiveness of cancers. Small case studies have reached similar conclusions. A controlled prospective trial of induced hypothyroidism beneficially affected the course of glioblastoma. A context in which to interpret such findings is the recent description of a plasma membrane receptor for thyroid hormone on cancer cells and dividing tumor-associated endothelial cells.

SUMMARY

Accumulating clinical evidence may justify new, broadly-based controlled studies in cancer patients of the possible contribution of thyroid hormone to tumor behavior.

Influence of estradiol and triiodothyronine on breast cancer cell lines proliferation and expression of estrogen and thyroid hormone receptors

OBJECTIVE

To better understand the estrogen (E2) agonist action of triiodothyronine (T3) the effects of these hormones on ER negative MDA-MB-231 breast cancer cells were compared with those on S30, a clone of MDA-MB-231 stably transfected with ERalpha cDNA, in terms of proliferation and modulation of hormone receptors.

RESULTS

Growth experiments showed that MDA-MB-231 was not modulated by any hormone or tamoxifen (TAM). Treatment with E2, 10(-8)M or 10(-9)M had little effect on S30 proliferation. T3 at 10(-8)M significantly inhibited proliferation. This effect was not reverted by TAM. Treatments with 10(-8)M concentration of E2 or T3 reduced ERalpha gene expression in S30, an effect partially blocked by association with TAM, with no effect on TR expression. These results suggest that, in S30, 10(-8)M T3 has a similar action to E2 relative to ERalpha gene modulation.

CONCLUSIONS

Such results emphasize the need of determining T3 levels, before the introduction of antiestrogenic forms of treatment in breast cancer patients.