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

The association between infectious agents and breast cancer: a review of the epidemiologic evidence

PURPOSE

Several viruses have been casually linked to human cancers, including cervical, nasopharyngeal, liver, sarcoma, and Merkel cell carcinomas. However, the etiologic contribution of viral infections to breast cancer, the number one incident cancer among women worldwide, is not well established. Among studies exploring associations of viruses with breast cancer, potential linkages have been identified between breast cancer and five viruses: beta retrovirus, (i.e., mouse mammary tumor virus), human papillomavirus, Epstein Barr virus. bovine leukemia virus, and human cytomegalovirus.

METHODS

In this review, we provide a comprehensive evaluation of epidemiological ecologic, case-control, case-only, and cohort studies investigating these associations. We discuss results from several existing reviews and meta-analyses, evaluate epidemiological studies published in the past five years, and assess the relationship between these viruses and breast tumor clinicopathological factors.

RESULTS

The strongest epidemiological evidence for a viral role in breast cancer exists for MMTV and HPV, though limitations include lack of prospective studies for MMTV and potential detection bias in HPV studies. Viral detection challenges have limited studies of EBV and HCMV. Fewer studies have evaluated BLV, and though it has been associated with higher risk of breast cancer, sample sizes are quite small.   CONCLUSION: While epidemiologic evidence exists for an association between these five viruses and breast cancer, various methodological issues and lack of prospective studies preclude robust conclusions. Future research should prioritize establishing a temporal relationship between infection and disease, minimizing misclassification of detection assays, and further exploring the influence of co-infections.

Non-genetic factors and breast cancer: an umbrella review of meta-analyses

BACKGROUND

Previous research has found associations between various non-genetic factors and breast cancer (BrCa) risk. This study summarises and appraises the credibility of the available evidence on the association between non-genetic factors and BrCa risk.

METHODS

We conducted an umbrella review of meta-analyses. Medline, Scopus, and the Cochrane databases were systematically searched for meta-analyses examining non-genetic factors and BrCa incidence or mortality. The strength of the evidence was graded in four categories (i.e., weak, suggestive, highly suggestive, convincing).

RESULTS

A total of 781 meta-analyses from 280 publications were evaluated and graded. We included exposures related to anthropometric measurements, biomarkers, breast characteristics and diseases, diet and supplements, environment, exogenous hormones, lifestyle and social factors, medical history, medication, reproductive history, and pregnancy. The largest number of examined associations was found for the category of diet and supplements and for exposures such as aspirin use and active smoking. The statistically significant (P-value < 0.05) meta-analyses were 382 (49%), of which 204 (53.4%) reported factors associated with increased BrCa risk. Most of the statistically significant evidence (n = 224, 58.6%) was graded as weak. Convincing harmful associations with heightened BrCa risk were found for increased body mass index (BMI), BMI and weight gain in postmenopausal women, oral contraceptive use in premenopausal women, increased androstenedione, estradiol, estrone, and testosterone concentrations, high Breast Imaging Reporting and Data System (BIRADS) classification, and increased breast density. Convincing protective factors associated with lower BrCa risk included high fiber intake and high sex hormone binding globulin (SHBG) levels while highly suggestive protective factors included high 25 hydroxy vitamin D [25(OH)D] levels, adherence to healthy lifestyle, and moderate-vigorous physical activity.

CONCLUSIONS

Our findings suggest some highly modifiable factors that protect from BrCa. Interestingly, while diet was the most studied exposure category, the related associations failed to reach higher levels of evidence, indicating the methodological limitations in the field. To improve the validity of these associations, future research should utilise more robust study designs and better exposure assessment techniques. Overall, our study provides knowledge that supports the development of evidence-based BrCa prevention recommendations and guidance, both at an individual level and for public health initiatives.

TRIAL REGISTRATION

PROSPERO CRD42022370675.

The Influence of Tumor-Specific Markers in Breast Cancer on Other Blood Parameters

BACKGROUND

Breast cancer is the most frequently diagnosed cancer among women, responsible for the highest number of cancer-related deaths worldwide. There is limited data available related to serum tumor markers in breast cancer and other blood parameters or other glandular laboratory parameters. This study aims to evaluate the correlation of tumor-specific markers for breast cancer with other blood parameters and how these correlations could impact clinical management.

MATERIAL AND METHOD

This retrospective study represents a data analysis from 1 January 2020 to 31 May 2023, in the County Hospital of Timisoara, Romania. We reviewed all the cases where, in the laboratory analyses, the serum tumor specific biomarkers for breast cancer were analyzed.

RESULTS

A statistical analysis was performed in order to identify a possible relationship between CA 15-3 and the various biomarkers and blood parameters included in the present study. Values were classified according to reference ranges. The tests revealed no statistically significant associations between CA 15-3 values and the levels of CA125 (χ2(1) = 1.852, p = 0.174), CEA (χ2(1) = 1.139, p = 0.286), AFP (Fisher's exact test, p = 0.341), fT4 (Fisher's exact test, p = 0.310), TSH (Fisher's exact test, p = 0.177), or PTH (Fisher's exact test, p = 0.650).

CONCLUSION

The findings indicate a lack of strong correlation between CA 15-3 and CA125, CEA, AFP, thyroid function markers, or PTH within this cohort.

The crosstalk between benign thyroid disease and breast cancer: A single center study

This study aims to investigate the relationship between benign thyroid disease and breast cancer. The clinical study includes a total of 600 participants, divided into 2 groups: the control group (N = 300), which consists of individuals from the checkup population during the same periods, and the experimental group (N = 300), which consists of patients with breast cancer. General data of the participants, including age, tumor diameter, tumor staging, pathological classification, lymph node metastasis, and classification of benign thyroid disease, were collected and analyzed. The levels of TT3, TT4, FT3, FT4, TSH, TPOAb, and TgAb in blood samples from the experimental and control groups were determined using a radioimmune method. The levels of TPOAb, TgAb, and TSH in the experimental group were significantly higher than those in the control group, while the levels of TT3, TT4, FT3, and FT4 in the experimental group were significantly lower. The general data of the participants contributed to the appropriate sample size and allocation. Furthermore, benign thyroid disease contributes to the development of breast cancer by regulating the levels of TT3, TT4, FT3, FT4, TSH, TPOAb, and TgAb.

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.

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.

Benign thyroid disease and the risk of breast cancer: An updated systematic review and meta-analysis

Background

The correlation between benign thyroid disease (BTD) and breast cancer (BC) has long been discussed. However, the definite relationship and potential mechanism between them are still disputed. The current meta-analysis aimed at performing a comprehensive assessment of the relationship between different types of benign thyroid disease and the risk of breast cancer, furthermore, assessing whether benign thyroid disease exerts an influence on the aggressiveness of breast cancer.

Method

A systematic literature search (PubMed, Web of Science, MEDLINE, and Embase databases) identified studies to evaluate the correlation between BTD and BC risk. Data were analyzed using version 16.0 STATA software, including the odds ratio (OR) and its corresponding 95% confidence intervals (CIs). Publication bias and quality assessment were conducted for the included studies.

Result

Overall, 18 studies involving 422,384 patients with BTD were incorporated. The outcome showed that autoimmune thyroiditis (OR: 2.56, 95%CI: 1.95-3.37, I2 = 0.0%, p=0.460), goiter (OR: 2.13, 95%CI: 1.19-3.79, I2 = 80.6%, p=0.000), and Graves' disease (OR: 5.01, 95%CI: 1.49-16.82, I2 = 0.0%, p=0.358) was connected with a higher risk of BC. Both hypothyroidism (OR: 0.82, 95%CI: 0.64-1.04, I2 = 85.0%, p=0.000) and hyperthyroidism (OR: 1.07, 95%CI: 0.93-1.24, I2 = 24.9%, p=0.206) had no significant association with the risk of BC. Additionally, the pooled analysis showed no apparent correlation between BTD and aggressiveness of BC. However, subgroup analysis indicated a positive relationship between BTD and aggressiveness of BC in the Europe subgroup (HR: 2.05, 95%CI: 1.32-3.17, I2 = 86.4%, p=0.000).

Conclusion

Autoimmune thyroiditis, goiter, and Graves' disease are connected with an increased risk of BC. Furthermore, subgroup analysis suggested that BTD increases the aggressiveness of BC in the European population geographically. Nevertheless, further research is needed to prove these discoveries.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSION

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

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.

Epidemiological survey of the status of iodine nutrition and thyroid diseases in Guangxi, China

OBJECTIVE

To survey the status of iodine nutrition and the prevalence of thyroid diseases in Guangxi, China, and to explore the risk factors for positive thyroid antibody.

METHODS

We used the multistage stratified cluster random sampling method to select a total of 2488 subjects from an urban and a rural location. All the subjects completed a questionnaire survey, blood and urine samples were also collected, and B-mode thyroid ultrasound was used to determine thyroid function and detect thyroid antibodies.

RESULTS

1) The median level of urinary iodine was 148.53 μg/L in school-age children in Guangxi, China. 2) The prevalence rates for thyroid diseases were as follows: hyperthyroidism, 0.89 %; subclinical hyperthyroidism, 1.05 %; hypothyroidism, 0.69 %; and subclinical hypothyroidism, 8.87 %. The rates of thyroid antibody positivity were as follows: thyroid peroxidase antibody (TPOAb), 13.60 %; thyroglobulin antibody (TGAb), 13.60 %; thyroid antibodies, 18.2 %; and thyroid nodules, 16.94 %. 3) The rate of TPOAb positivity was significantly higher in women aged 18-29, 30-39, 40-49, or 60-69 years than in men in the same age groups (P < 0.05), and the TGAb positivity rate was significantly higher in women than in men of the same age group (P < 0.05). 4) The rate of thyroid antibody positivity was significantly higher in individuals with iodine deficiency than in individuals with adequate iodine (21.6 % vs 18.4 %) or excess iodine (21.6 % vs 15.5 %) (both P < 0.05). 5) The female sex and a family history of thyroid diseases were the major risk factors for thyroid antibody positivity (odds ratio [OR] 3.010, P <0.05; OR 2.486, P <0.05).

CONCLUSION

The overall level of iodine is adequate in Guangxi, China; this level should be maintained to prevent the thyroid diseases related with iodine deficiency or excess of iodine. Female sex and a family history of thyroid diseases are independent risk factors for thyroid antibody positivity.

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.

Bilateral breast myxedema caused by Graves' disease and responsive to multipoint subcutaneous injection of long-acting glucocorticoid: Case report

RATIONALE

With the absence of ophthalmopathy, thyroid dermopathy especially lesions at atypical locations is a very rare presentation. We herein report an original case of bilateral breast myxedema caused by Grave's disease.

PATIENT CONCERNS

A 21-year-old unmarried woman presented with a 4-month history of Grave's disease and a 1-month history of progressive bilateral breast enlargement. She had symmetrical bilateral breast enlargement with redness and nonpitting thickening of the skin, diffusely enlarged thyroid glands, and no exophthalmos.

DIAGNOSIS

Ultrasonography, magnetic resonance imaging scan, and skin biopsy confirmed the diagnosis of bilateral breast myxedema.

INTERVENTIONS

The patient was treated with multipoint subcutaneous injections of triamcinolone acetonide in each breast every month.

OUTCOMES

The bilateral breast returned approximately to its normal size after therapy for 6 months.

CONCLUSIONS

Our case illustrates that multipoint subcutaneous injection of glucocorticoids is beneficial for bilateral breast myxedema.

Co-occurrence of thyroid and breast cancer is associated with an increased oncogenic SNP burden

BACKGROUND

Epidemiological evidence suggests that synchronous or metachronous presentation of breast and thyroid cancers exceeds that predicted by chance alone. The following potential explanations have been hypothesized: common environmental or hormonal factors, oncogenic effect of the treatment for the first cancer, closer follow-up of cancer survivors, shared underlying genetic risk factors. While some cases were found to be related to monogenic disorders with autosomal inheritance, the genetic background of most cases of co-occurring breast and thyroid cancer is thought to be polygenic.

METHODS

In this retrospective case-control study we compared the genetic profile of patients with a history of breast cancer (n = 15) to patients with co-occurring breast and thyroid cancer (n = 19) using next generation sequencing of 112 hereditary cancer risk genes. Identified variants were categorized based on their known association with breast cancer and oncogenesis in general.

RESULTS

No difference between patients with breast and double cancers was observed in clinical and pathological characteristics or the number of neutral SNPs. The unweighted and weighted number of SNPs with an established or potential association with breast cancer was significantly lower in the group with breast cancer only (mean difference - 0.58, BCa 95% CI [- 1.09, - 0.06], p = 0.029, and mean difference - 0.36, BCa 95% CI [- 0.70, - 0.02], p = 0.039, respectively). The difference was also significant when we compared the number of SNPs with potential or known association with any malignancy (mean difference - 1.19, BCa 95% CI [- 2.27, - 0.11], p = 0.032 for unweighted, and mean difference - 0.73, BCa 95% CI [- 1.32, - 0.14], p = 0.017 for weighted scores).

CONCLUSION

Our findings are compatible with the hypothesis of genetic predisposition in the co-occurrence of breast and thyroid cancer. Further exploration of the underlying genetic mechanisms may help in the identification of patients with an elevated risk for a second cancer at the diagnosis of the first cancer.

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.

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.

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.

Risk of Breast Cancer in Females With Hypothyroidism: A Nationwide, Population-Based, Cohort Study

OBJECTIVES

The results of studies investigating the relationship between breast cancer and hypothyroidism vary greatly from study to study. In this study, we analyzed a large and reliable, population-based database to gain a better understanding of the correlation.

METHODS

This retrospective cohort study analyzed patients with hypothyroidism between January 1, 2000 and December 31, 2012 (hypothyroidism cohort) from the Longitudinal Health Insurance Database 2000 in Taiwan. For each woman with hypothyroidism, 1 woman without a history of breast cancer was randomly selected from the Longitudinal Health Insurance Database 2000 and frequency matched (1:4) with women without hypothyroidism by age and index year of hypothyroidism. The study outcome was the diagnosis of breast cancer during a 12-year follow-up period.

RESULTS

In this study, 6665 women with hypothyroidism and 26 660 women without hypothyroidism were identified. The hypothyroidism cohort had a significantly higher risk of breast cancer than the nonhypothyroidism cohort (adjusted hazard ratio [aHR] 1.69 [95% CI, 1.15-2.49]; P = .01), especially in the group aged 40 to 64 years (aHR 2.07 [95% CI, 1.32-3.23]; P = .01). Women in the hypothyroidism cohort taking levothyroxine for a duration ˃588 days showed a significantly decreased risk of breast cancer (aHR 0.37 [95% CI, 0.19-0.71]; P = .003).

CONCLUSION

Women with hypothyroidism are at a higher risk of breast cancer than those without hypothyroidism. Levothyroxine may reduce the risk of breast cancer in a woman with hypothyroidism.

Causal associations of thyroid function and dysfunction with overall, breast and thyroid cancer: A two-sample Mendelian randomization study

Whether thyroid dysfunction plays a causal role in the development of cancer remains inconclusive. We conducted a two-sample Mendelian randomization study to investigate the associations between genetic predisposition to thyroid dysfunction and 22 site-specific cancers. Single-nucleotide polymorphisms associated with four traits of thyroid function were selected from a genome-wide association meta-analysis with up to 72,167 European-descent individuals. Summary-level data for breast cancer and 21 other cancers were extracted from the Breast Cancer Association Consortium (122,977 breast cancer cases and 105,974 controls) and UK Biobank (367,643 individuals). For breast cancer, a meta-analysis was performed using data from both sources. Genetically predicted thyroid dysfunction was associated with breast cancer, with similar patterns of associations in the Breast Cancer Association Consortium and UK Biobank. The combined odds ratios of breast cancer were 0.94 (0.91-0.98; p = 0.007) per genetically predicted one standard deviation increase in TSH levels, 0.96 (0.91-1.00; p = 0.053) for genetic predisposition to hypothyroidism, 1.04 (1.01-1.07; p = 0.005) for genetic predisposition to hyperthyroidism and 1.07 (1.02-1.12; p = 0.003) per genetically predicted one standard deviation increase in free thyroxine levels. Genetically predicted TSH levels and hypothyroidism were inversely with thyroid cancer; the odds ratios were 0.47 (0.30-0.73; p = 0.001) and 0.70 (0.51-0.98; p = 0.038), respectively. Our study provides evidence of a causal association between thyroid dysfunction and breast cancer (mainly ER-positive tumors) risk. The role of TSH and hypothyroidism for thyroid cancer and the associations between thyroid dysfunction and other cancers need further exploration.

Synchronous papillary thyroid carcinoma and breast ductal carcinoma

A 48-year-old woman was admitted to our hospital with a lump in her left breast. She was diagnosed with synchronous papillary thyroid carcinoma and breast ductal carcinoma. The patient underwent four cycles of neoadjuvant chemotherapy with epirubicin and cyclophosphamide, and one cycle of docetaxel. She then underwent left breast mastectomy and radical resection of thyroid cancer (total thyroidectomy and bilateral central group [levels VI and VII] lymph node dissection) at the same time. She was administered three cycles of chemotherapy with docetaxel and radiotherapy. The patient had no metastasis in the follow-up period. A literature search was performed to characterize the epidemiology, etiology, management, and prognosis of this condition. We speculate that hormone treatment could be a probable pathogenesis of synchronous breast and thyroid cancers.

Does hypothyroidism increase the risk of breast cancer: evidence from a meta-analysis

PURPOSE

At present, the relationship between hypothyroidism and the risk of breast cancer is still inconclusive. This meta-analysis was used to systematically assess the relationship between hypothyroidism and breast cancer risk, and to assess whether thyroid hormone replacement therapy can increase breast cancer risk.

METHODS

The relevant articles about hypothyroidism and the risk of breast cancer were obtained on the electronic database platform. Relevant data were extracted, and odd ratios (OR) with corresponding 95% confidence intervals (CI) were merged using Stata SE 12.0 software.

RESULTS

A total of 19 related studies were included in the meta-analysis, including 6 cohort studies and 13 case-control studies. The results show that hypothyroidism was not related to the risk of breast cancer (odd ratios = 0.90, 95% CI 0.77-1.03). In the European subgroup, we observed that patients with hypothyroidism have a lower risk of breast cancer(odd ratios = 0.93, 95% CI 0.88-0.99). Furthermore, no significant correlation was observed between thyroid hormone replacement therapy and the risk of breast cancer. (odd ratios = 0.87, 95% CI 0.65-1.09).

CONCLUSION

Hypothyroidism may reduce the risk of breast cancer in the European population, and no significant correlation was observed between hypothyroidism and breast cancer risk in non-European populations. Due to the limited number of studies included, more large-scale, high-quality, long-term prospective cohort studies are needed.

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.

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.

Risk of breast cancer in women with non-lactational mastitis

Little is known regarding the association of non-lactational mastitis women with breast cancer risk. This population-based cohort study examined the breast cancer risk in women with non-lactational mastitis. We identified 3,091 women with non-lactational mastitis between 2000 and 2011 using the Taiwan National Health Insurance Research Database. We performed 1:4 propensity score matching by age, socioeconomic status and comorbidities and identified 12,364 women without non-lactational mastitis. The mean age of women with non-lactational mastitis was 37.9 years; these women had a higher breast cancer risk than the comparison group (adjusted hazard ratio = 1.94, 95% confidence interval: 1.30–2.90). The incidence rates of breast cancer in women with non-lactational mastitis and the comparison group were 14.79 and 7.57 per 10,000 person-years, respectively. Furthermore, non-lactational mastitis was a risk factor for breast cancer in women aged <50 years, women with lower socioeconomic status and women with hormonal medication (p < 0.05). Women who had more episodes of non-lactational mastitis had a higher risk of developing a breast cancer. Thus, the risk of breast cancer in women with non-lactational mastitis is significantly higher than those without non-lactational mastitis.

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.

Hypothyroidism and related diseases: a methodological quality assessment of meta-analysis

OBJECTIVES

There is an increasing prevalence of hypothyroidism and there is a growing body of meta-analyses (MAs) on the association between hypothyroidism and other diseases. However, the methodological quality of the MAs significantly varies. Thus, this study aimed to evaluate and summarise data on the methodological quality of MAs on the associations between hypothyroidism and other diseases using the Assessment of Multiple Systematic Reviews (AMSTAR) scale, providing suggestions for clinical decision-making processes.

DESIGN

To assess the methodological quality of MAs using the AMSTAR scale.

DATA SOURCES

A systematic literature search was performed in PubMed, EMBASE, the Cochrane Library, web of science and Chinese Biomedicine Literature Database.

ELIGIBILITY CRITERIA

We included MAs that had assessed the association between hypothyroidism and other diseases in humans and that had full texts regardless of the publication status. No restriction applied on language or date.

DATA EXTRACTION AND SYNTHESIS

Two reviewers independently screened the titles and abstracts of all searched literature to acquire potentially eligible publications. The full texts of possible eligible publications were downloaded and assessed. Inconsistent comments were resolved through discussions with a third reviewer.

RESULTS

52 studies were included. The average AMSTAR score of the included articles was 8.6 (range: 5-10), and those of English and Chinese MAs were 8.8 and 7.0, respectively. A total of 52 MAs were evaluated, and 19 (36.5%) and 33 (63.5%) of these MAs were of moderate and high quality, respectively. None of the MAs were of low quality. Only two MAs had an a priori design. Items 3, 5 and 9 had the highest compliance (50/52, 96.2%), and aside from item 1, items 7 and 8 had the lowest compliance (33/52,63.5%). According to the results of these MAs, hypothyroidism was significantly associated with cardiovascular diseases, metabolic diseases, neuropsychiatric disorders, breast cancer and pregnancy outcome.

CONCLUSIONS

The methodological quality of the included MAs on the association between hypothyroidism and other diseases was moderate to high. MAs with high qualities confirmed that hypothyroidism was significantly associated with cardiovascular diseases, metabolic syndrome, preterm birth and neonatal outcomes. Consideration of scientific quality when formulating conclusions should be made explicit and more attention should be paid to improving the methodological quality of MAs, and increasing their applicability for clinical decision-making.

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.

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.

Retrospective Analysis of Patients with Synchronous Primary Breast and Thyroid Carcinoma

Objective

Breast and thyroid cancers are commonly encountered malignancies. Increased risk of breast cancer in follow-up period of thyroid cancer or vice versa has been reported. However, they have some associations, synchronous presentation of these tumors is rare. We presented 12 patients diagnosed as breast and thyroid cancer and treated at the same time.

Materials and Methods

Mastectomy and thyroidectomy were performed in 19 patients at the same time. 7 patients were excluded because of benign thyroid pathology. Therefore 12 patients who had diagnosis of synchronous breast and thyroid cancer were included. Data regarding clinical, pathological, treatment and prognostic factors was retrospectively analyzed.

Results

Total thyroidectomy was performed in all patients. The mean age of patients was 54 years (min. 44-max. 70). Only one patient was male. Thyroid pathology was detected preoperatively by FDG PET-CT scan in 11 patients. Breast reconstruction was performed in three patients. The most commonly seen thyroid malignancy was papillary thyroid carcinoma. Postoperative complication rate was 33.3%. Adjuvant chemotherapy was given in 11 patients whereas one patient received adjuvant radiotherapy.

Conclusion

Although synchronous presentation of breast and thyroid cancer is rare, surgical treatment of both of these tumors can be safely performed at the same time. Association of these tumors should be evaluated by large scaled studies.

[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.

It is no longer the time to disregard thyroid metastases from breast cancer: a case report and review of the literature

BACKGROUND

Metastases to the thyroid gland are more frequent than previously thought, although most of them are occult or not clinically relevant. Overall, only 42 cases of metastases to thyroid from breast cancer have been reported thus far. Here we report the case of a patient with breast cancer metastatic to the thyroid. We also review the 42 previously reported cases (published between 1962 and 2012). This is the first review about metastases to thyroid gland from breast cancer.

CASE PRESENTATION

A 64-year-old woman of Caucasian origin was diagnosed with a lobular invasive carcinoma of the breast (luminal A, stage II). She received adjuvant chemotherapy, followed by endocrine therapy. During follow-up, fine-needle cytology of a thyroid nodule revealed malignant cells that were estrogen-positive, which suggested a diagnosis of metastases to the thyroid. Imaging did not reveal any other metastatic site and showed only enlargement of the left thyroid lobe and an inhomogeneous pattern of colloid and cystic degeneration and calcifications. The patient underwent left hemithyroidectomy. Histology of thyroid tissue showed a colloid goitre containing dispersed small atypical neoplastic cells with eccentric nuclei. Immunohistochemistry showed cytokeratin-19 and oestrogen receptor, but not tireoglobulin, e-cadherin or cytokeratin-7, thereby confirming metastases from a lobular breast carcinoma. Hormonal treatment is ongoing.

CONCLUSION

This case report and first review of the literature on metastases to thyroid from breast cancer highlight the importance of a correct early diagnostic work-up in such cases. Indeed, a primary lesion should be distinguished from metastases given the different treatment protocol related to primary cancer and the clinical impact on prognosis.

Impact of autoimmune diseases on outcome of patients with early breast cancer

Our aim was to analyze the impact of a concurrent autoimmune disease on outcome of patients with early breast cancer. We reviewed medical charts of patients with a diagnosis of autoimmune diseases (AD) among a population of 17.153 cases. We categorized ADs as endocrine, rheumatic, systemic, neurological diseases and vasculitis. For each patient in the study group, we matched 2 patients. The events to determine overall survival (OS) and disease free survival (DFS) were identified from follow-up data. We identified 279 (1.62%) patients with early breast cancer and concurrent ADs. The median follow-up was 7.0 years. The 10-year OS rate was 86% (95% CI, 80% to 91%) in the study group and 90% (95% CI, 86% to 93%) for the control group (p = 0.011). In patients with ER positive/HER2 negative subtype a worse OS was observed in the study group when compared to the control group (p = 0.0046); this difference remained statistically significant when the analysis was restricted to breast cancer mortality (p = 0.045). The 10-year DFS rate was 69% (95% CI, 61% to 76%) in the study group and 72% (95% CI, 66% to 77%) for the control group (p = 0.22). Autoimmunity at diagnosis of early breast cancer is associated with worse survival.

Occupational pesticide exposure and subclinical hypothyroidism among male pesticide applicators

OBJECTIVES

Animal studies suggest that exposure to pesticides may alter thyroid function; however, few epidemiologic studies have examined this association. We evaluated the relationship between individual pesticides and thyroid function in 679 men enrolled in a substudy of the Agricultural Health Study, a cohort of licensed pesticide applicators.

METHODS

Self-reported lifetime pesticide use was obtained at cohort enrolment (1993-1997). Intensity-weighted lifetime days were computed for 33 pesticides, which adjusts cumulative days of pesticide use for factors that modify exposure (eg, use of personal protective equipment). Thyroid-stimulating hormone (TSH), thyroxine (T4), triiodothyronine (T3) and antithyroid peroxidase (anti-TPO) autoantibodies were measured in serum collected in 2010-2013. We used multivariate logistic regression to estimate ORs and 95% CIs for subclinical hypothyroidism (TSH >4.5 mIU/L) compared with normal TSH (0.4-<4.5 mIU/L) and for anti-TPO positivity. We also examined pesticide associations with TSH, T4 and T3 in multivariate linear regression models.

RESULTS

Higher exposure to the insecticide aldrin (third and fourth quartiles of intensity-weighted days vs no exposure) was positively associated with subclinical hypothyroidism (ORQ3=4.15, 95% CI 1.56 to 11.01, ORQ4=4.76, 95% CI 1.53 to 14.82, ptrend <0.01), higher TSH (ptrend=0.01) and lower T4 (ptrend=0.04). Higher exposure to the herbicide pendimethalin was associated with subclinical hypothyroidism (fourth quartile vs no exposure: ORQ4=2.78, 95% CI 1.30 to 5.95, ptrend=0.02), higher TSH (ptrend=0.04) and anti-TPO positivity (ptrend=0.01). The fumigant methyl bromide was inversely associated with TSH (ptrend=0.02) and positively associated with T4 (ptrend=0.01).

CONCLUSIONS

Our results suggest that long-term exposure to aldrin, pendimethalin and methyl bromide may alter thyroid function among male pesticide applicators.

Thyroid-associated genetic polymorphisms in relation to breast cancer risk in the Malmö Diet and Cancer Study

Previous studies have suggested that thyroid function is associated with breast cancer risk, which could have an important clinical impact, as one in eight women will develop a thyroid disorder during her lifetime. However, the underlying pathomechanism behind the association is still unknown. We used the Malmö Diet and Cancer Study (a population-based prospective study consisting of 17,035 women) to examine 17 single nucleotide polymorphisms (SNPs) previously related to levels of free thyroxine (free T4) and thyroid peroxidase antibodies (TPO-Ab) as potential genetic risk factors for breast cancer. A baseline examination including free T4 and TPO-Ab levels was conducted at the time of inclusion. Genotyping was performed on 901 breast cancer patients and 3335 controls. Odds ratios (95% confidence intervals) for high free T4, TPO-Ab positivity, and breast cancer were calculated by logistic regression and adjusted for confounders. We identified one free T4-related SNP (rs2235544, D101 gene) that was significantly associated with both free T4 level and breast cancer risk. There was a suggested association between rs11675434 (TPO gene) and TPO-Ab level, and TPO-Ab-related rs11675434 (TPO), rs3094228 (HCP5), rs1033662 (no registered gene), and rs301806 (RERE) were associated with breast cancer risk. There was an indicated interaction between rs6485050 (no registered gene) and free T4 level in regards to breast cancer risk. This is the first study to suggest an association between thyroid-related SNPs and breast cancer risk. All SNPs have a biological plausibility of being associated with breast cancer risk, and may contribute to the genetic predisposition to breast cancer.

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.

Study on the status of thyroid function and thyroid nodules in chinese breast cancer patients

We performed a study to investigate the status of thyroid nodules and thyroid functions in Chinese breast cancer women. The clinical data of female patients with breast cancer or benign breast diseases and normal populace were evaluated. The thyroxine(T4) level in initially diagnosed breast cancer patients were significantly higher than those in benign breast diseases patients (7.68±1.51 vs 7.29±1.52ug/dl, p<0.001), while the TSH levels were slightly lower than in benign breast diseases patients(3.23±4.59 vs 3.60±6.74uIU/ml, p=0.302). The overall incidence of hypothyroidism in initially diagnosed breast cancer and benign breast diseases patients were 28.65% and 32.74%(p=0.195). During chemotherapy, the T4(7.08±1.69ug/dl), fT3(2.87±0.48pg/ml) and fT4(0.83±0.15ng/dl) levels were significantly lower than in initially diagnosed breast cancer patients(7.68±1.51ug/dl, 3.07±0.50pg/ml, 0.88±0.20ng/dl, p<0.05). The incidence of thyroid nodules in initially diagnosed breast cancer patients, benign breast diseases patients and healthy population were 56.17%, 43.64%, 34.49%(p<0.001). The incidence of TI-RADS≥4 TN in initially diagnosed breast cancer patients and benign breast diseases patients were significantly higher than in normal population(7.27% vs 9.45% vs 2.87%, p<0.001). The incidence of TI-RADS≥4 thyroid nodules in breast cancer patients receiving chemotherapy was significantly higher than in initially diagnosed breast cancer patients(11.71% vs 7.27%, p<0.05). These data indicate that the incidence of thyroid disease in breast disease patients is higher than in normal population in China, and the breast diseases, especially breast cancer, might be related to the high incidence of thyroid nodules.

Hyperthyroidism, Hypothyroidism, and Cause-Specific Mortality in a Large Cohort of Women

BACKGROUND

The prevalence of hyperthyroidism and hypothyroidism is 0.5-4% in iodine-replete communities, but it is 5-10 times higher in women than in men. Those conditions are associated with a broad range of metabolic disorders and cardiovascular diseases. Biological evidence of a role of thyroid hormones in carcinogenesis also exists. However, the association between thyroid dysfunction and cardiovascular disease or cancer mortality risk remains controversial. In a large cohort of women, the associations of hyperthyroidism and hypothyroidism with cause-specific mortality were evaluated after nearly 30 years of follow-up.

METHODS

The prospective study included 75,076 women aged 20-89 years who were certified as radiologic technologists in the United States in 1926-1982, completed baseline questionnaires in 1983-1998 from which medical history was ascertained, and reported no malignant disease or benign thyroid disease except thyroid dysfunction. A passive follow-up of this cohort was performed through the Social Security Administration database and the National Death Index-Plus. Cause-specific mortality risks were compared according to self-reported thyroid status, with proportional hazards models adjusted for baseline year and age, race/ethnicity, body mass index, family history of breast cancer, and life-style and reproductive factors.

RESULTS

During a median follow-up of 28 years, 2609 cancer, 1789 cardiovascular or cerebrovascular, and 2442 other non-cancer deaths were recorded. Women with hyperthyroidism had an elevated risk of breast cancer mortality after 60 years of age (hazard ratio [HR] = 2.04 [confidence interval (CI) 1.16-3.60], 13 cases in hyperthyroid women) compared to women without thyroid disease. Hypothyroid women had increased mortality risks for diabetes mellitus (HR = 1.58 [CI 1.03-2.41], 27 cases in hypothyroid women), cardiovascular disease (HR = 1.20 [CI 1.01-1.42], 179 cases), and cerebrovascular disease (HR = 1.45 [CI 1.01-2.08], 35 cases, when restricting the follow-up to ≥10 years after baseline). Other causes of death were not associated with hyperthyroidism or hypothyroidism, though there was a suggestion of an elevated risk of ovarian cancer mortality in hyperthyroid women based on very few cases.

CONCLUSION

The excess mortality risks observed in a large, prospective 30-year follow-up of patients with thyroid dysfunction require confirmation, and, if replicated, further investigation will be needed because of the clinical implications.

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 peroxidase (TPO) expressed in thyroid and breast tissues shows similar antigenic properties

BACKGROUND

Thyroid peroxidase (TPO) is essential for physiological function of the thyroid gland. The high prevalence of thyroid peroxidase antibodies (TPOAbs) in patients with breast cancer and their protective role had previously been demonstrated, indicating a link between breast cancer and thyroid autoimmunity. Recently, TPO was shown to be present in breast cancer tissue samples but its antigenicity has not been analyzed.

METHODS

In this study, we investigated TPO expression levels in a series of fifty-six breast cancer samples paired with normal (peri-tumoral) tissue and its antigenic activity using a panel of well-characterized murine anti-human TPOAbs.

RESULTS

We have shown that TPO transcripts were present in both normal and cancer tissue samples, although the amounts in the latter were reduced. Additionally, we observed that TPO levels are lower in more advanced cancers. TPO protein expression was confirmed in all tissue samples, both normal and cancerous. We also found that the antigenicity of the immunodominant regions (IDRs) in breast TPO resembles that of thyroid TPO, which is crucial for effective interactions with human TPOAbs.

CONCLUSIONS

Expression of TPO in breast cancer together with its antigenic activity may have beneficial effects in TPOAb-positive breast cancer patients. However, further studies are needed to confirm the beneficial role of TPOAbs and to better understand the underlying mechanism.

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.

Thyroid disorders and mammographic density in Spanish women: Var-DDM study

OBJECTIVES

The association between breast cancer (BC) and thyroid disorders has been widely explored with unclear results. Mammographic density (MD) is one of the strongest risk factor for BC. This study explores the relationship between thyroid diseases and MD in Spanish women.

MATERIALS & METHODS

This cross-sectional study covered 2883 women aged 47-71 years participating in 7 BC screening programs in 2010. They allowed access to their mammograms, had anthropometrical-measures taken, and answered a telephonic epidemiological interview which included specific questions on thyroid diseases. Percentage of MD was assessed with a semiautomatic-computer tool (DM-scan) by two trained radiologists. We calculated the geometric mean of MD percentages (mean MD). Multivariable mixed linear regression models with random screening-center-specific intercepts were fitted, using log-transformed percentage of MD as dependent variable and adjusting for age, body mass index, menopausal status and other confounders. e^β represents the relative increase of mean MD.

RESULTS

13.9% of the participants reported personal history of thyroid disease. MD was not associated to hyperthyroidism (e^β:1.05, 95%CI: 0.82-1.36), hypothyroidism (e^β:1.02, 95%CI: 0.75-1.38), thyroid nodules (e^β:1.01, 95%CI: 0.85-1.19) or thyroid cancer (e^β:1.03, 95%CI: 0.56-1.92). However, women with goiter had lower MD (mean MD_no-goiter: 13.4% vs mean MD_goiter: 10.6%; e^β:0.79, 95%CI: 0.64-0.98) and those with Hashimoto thyroiditis had higher MD (mean MD_{no-thyroiditis}: 13.3% vs mean MD_thyroidits: 25.8%; e^β:1.94, 95%CI: 1.00-3.77).

CONCLUSION

Functional thyroid disorders were not related to MD. However, MD was lower in women with goiter and higher in those reporting Hashimoto's thyroiditis. These relationships should be confirmed in future studies.

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.

Is there an association between thyroid function abnormalities and breast cancer?

OBJECTIVE

The aim of this study was to evaluate the association between thyroid function abnormalities and breast cancer and, in particular, the prognostic markers of breast cancer..

SUBJECTS AND METHODS

Baseline levels of thyrotropin, free triiodothyronine, free thyroxine and thyroid autoantibodies were measured in 97 women with primary breast cancer, 27 women with benign breast disease, and 4 women with atypical ductal hyperplasia. Their baseline levels were compared with those in 48 healthy women with a normal mammography in the last 2 years.

RESULTS

There were no significant associations between history of thyroid disease and breast cancer (p = 0.33). The mean baseline levels of triiodothyronine and thyrotropin did not differ significantly between the compared groups. The mean baseline levels of free thyroxine were found to be significantly higher in the breast cancer group, even after adjusting for thyroid replacement therapy. The presence of thyroid antibodies did not differ significantly between the compared groups. In a subgroup analysis, breast cancer cases with thyroid disease and particularly hypothyroidism had a significantly lower incidence of lymph node metastases compared with breast cancer cases without thyroid disease.

CONCLUSIONS

Our data confirmed the proliferative effect of thyroid hormones on breast cells, which had previously been shown in vitro. Additionally, thyroid disease and particularly hypothyroid function appeared to be associated with a lower incidence of lymph node metastases. Further studies to determine the prognostic role of thyroid hormones in breast cancer are warranted.

The thyroid and breast cancer

PURPOSE OF REVIEW

The female predominance of diseases of the thyroid and breast makes difficult the separation of an expected association with a causal linkage. This review will examine recent reports on associations between thyroid disease and breast cancer, comparing them with previous studies, with a view to elucidating what pointers are available to suggest either a common pathogenesis or novel thyroid-related therapeutic approach, which might arise from this association.

RECENT FINDINGS

Reports on thyroid-breast cancer associations are reviewed under the following headings: breast cancer prevalence in different thyroid disorders and their effect on risk and outcome; the possible role of thyroid autoimmunity, thyroid enlargement, effect of radioactive iodine treatment, role of stable iodine, possible joint antigens sodium iodide transporter and thyroid peroxidase and thyroid-breast cancer coincidence.

SUMMARY

Current studies on thyroid and breast cancer associations confirm earlier findings of the lack of definitive evidence of a causal relationship. The predominant relationship continues to be hypothyroidism or autoimmune thyroid disease perhaps contributing to increased breast cancer risk or outcomes. However, despite many studies and the findings of meta-analyses, elucidating the mechanisms underlying the association remains elusive. At present, there is little justification for utilizing thyroid insights as a possible therapeutic intervention in 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.

Rare Intensely Fluorine-18-fluorodeoxyglucose Avid Large Retropharyngeal Goiter in a Patient with Invasive Breast Carcinoma

Diffuse increased fluorine-18-fluorodeoxyglucose ((18)F-FDG) avidity on positron emission tomography (PET) scans has been demonstrated in patients with chronic thyroiditis, likely secondary to increased inflammatory cell glucose uptake. A complex association has been demonstrated between breast cancer and thyroid disease, although the mechanism remains elusive. Development of chronic thyroiditis and/or goiter in breast cancer patients has been suggested to convey a more favorable prognosis. Goiter extension is almost exclusively into retrosternal space, with only a handful of cases reported with superior extension into retropharyngeal space. We present a rare case of a diffusely enlarged goiter extending superior and posterior into the retropharyngeal space with an associated intense (18)F-FDG avidity standardized uptake value maximum (SUVmax) of 16.1 in a patient with invasive ductal breast cancer. To our knowledge, this represents the first published case of diffusely (18)F-FDG avid goiter with retropharyngeal extension.