Relation between estrogen receptor and malignancy of thyroid cancer

Reproductive Factors but Not Hormonal Factors Associated with Thyroid Cancer Risk: A Systematic Review and Meta-Analysis

Many studies have investigated the association between hormonal and reproductive factors and thyroid cancer risk but provided contradictory and inconclusive findings. This review was aimed at precisely estimating this association by pooling all available epidemiological studies. 25 independent studies were retrieved after a comprehensive literature search in databases of PubMed and Embase. Overall, common hormonal factors including oral contraceptive and hormone replacement therapy did not alter the risk of thyroid cancer. Older age at menopause was associated with weakly increased risk of thyroid cancer in overall analysis (RR = 1.24, 95% CI 1.00–1.53, P = 0.049); however, longer duration of breast feeding was related to moderately reduced risk of thyroid cancer, suggested by pooled analysis in all cohort studies (RR = 0.7, 95% CI 0.51–0.95, P = 0.021). The pooled RR in hospital-based case-control studies implicated that parous women were more susceptible to thyroid cancer than nulliparous women (RR = 2.30, 95% CI 1.31–4.04, P = 0.004). The present meta-analysis suggests that older age at menopause and parity are risk factors for thyroid cancer, while longer duration of breast feeding plays a protective role against this cancer. Nevertheless, more relevant epidemiological studies are warranted to investigate roles of hormonal and reproductive factors in thyroid carcinogenesis.

Role of estrogen in thyroid function and growth regulation

Thyroid diseases are more prevalent in women, particularly between puberty and menopause. It is wellknown that estrogen (E) has indirect effects on the thyroid economy. Direct effects of this steroid hormone on thyroid cells have been described more recently; so, the aim of the present paper was to review the evidences of these effects on thyroid function and growth regulation, and its mechanisms. The expression and ratios of the two E receptors, α and β, that mediate the genomic effects of E on normal and abnormal thyroid tissue were also reviewed, as well as nongenomic, distinct molecular pathways. Several evidences support the hypothesis that E has a direct role in thyroid follicular cells; understanding its influence on the growth and function of the thyroid in normal and abnormal conditions can potentially provide new targets for the treatment of thyroid diseases.

Gender differences in thyroid cancer: a critical review

It has long been known that the incidence of thyroid cancer in women is significantly higher than that in men. The objective of this article is to review gender differences in thyroid cancer, as well as epidemiological, clinical and experimental research on the role of sex hormones, their receptors and other molecular factors in this well-established thyroid cancer gender discrepancy. Although more common in women, thyroid cancer typically presents at a more advanced stage and with a worse disease prognosis in men. Clinical evidence on the impact of estrogen and other sex hormones on thyroid cancer has remained inconclusive, although numerous experimental studies have suggested that these hormones and their receptors may play a role in tumorigenesis and tumor progression. Studies of thyroid cancer cell lines suggest that an imbalance between the two estrogen receptor (ER) isoforms, α and β, may be responsible for the cell proliferation seen with estrogen treatment. Expression studies on thyroid tumors indicate that they express ER and possibly progesterone receptors and androgen receptors, but there is conflicting evidence as to whether or not there is a difference in receptor status between thyroid cancers, benign thyroid lesions and normal thyroid tissue. There have been few studies evaluating the ERα/ERβ profiles in thyroid tumors and normal thyroid tissue. Our understanding of the underlying basis for sex differences in thyroid cancer has improved over the last few decades, but the relationship between gender and thyroid cancer risk has remained elusive. Areas for future research include ERα/ERβ profiling of normal and neoplastic thyroid tissue, association between ER status and tumor dedifferentiation, and evaluation of the signaling pathways by which estrogen and other sex steroids exert their effects on thyroid cancer cells. Sex steroid receptors, and then downstream signaling pathways, represent promising future therapeutic targets for thyroid cancer treatment, and further study is required.

Postmenopause is associated with recurrence of differentiated papillary thyroid carcinoma

Differentiated papillary thyroid carcinoma (D-PTC) is the most common malignancy arising in the thyroid gland. There are gender differences in the incidence of PTC being mainly observed in females. Low-risk groups consisted of men younger than 40-year-old and women younger than 50-year-old, whereas the high-risk group are older patients. We believe that age is not enough to explain the clinical course of this neoplasm and hypothesize that aggressive behavior of D-PTC may be correlated with hormonal status. Studies that support this idea showed that the follicular neoplastic cells had higher estrogen receptor-alpha in premenopausal (28.1+/-4.5) than in postmenopausal women (14.2+/-2.9). According to author's prior observations, there are evidences correlating recurrence of D-PTC with postmenopause in women. Postmenopause status is characterized by estrogen decrease and FSH increases both associated with EGFR activation. Previous observations identified EGFR over-expression in D-PTC of postmenopause when compared with premenopausal ladies.

CONCLUSIONS

Postmenopause is an adverse factor for tumor evolution in women with D-PTC and is associated with EGFR expression. It's introduction in thyroid tumor stratification could be a fine tuning in predicting papillary thyroid carcinoma behavior.

Giant-cell tumors of bone and progesterone receptors

Estrogen receptors, progesterone receptors, and cathepsin D were determined in 10 patients with giant-cell bone tumor. Progesterone receptors were expressed in 5 of 10 patients tested, whereas low levels of estrogen receptors were found in 1 patient. Cathepsin D levels were elevated in 5 of 5 samples studied. High values of progesterone receptors correlated with low tumor grade. Cathepsin D levels correlated negatively with tumor grade but positively with local tumor expansion. Giant-cell bone tumor expressing progesterone receptors may manifest benign behavior. Cathepsin D may be involved in tumor expansion, possibly through its effect on bone resorption.

Epidemiology of reproductive and hormonal factors in thyroid cancer: evidence from a case-control study in the Middle East

Thyroid cancer is the second most common neoplasm among women in Kuwait and several other countries in the Middle East. Most of these countries also have relatively high birth and total fertility rates. To examine potential relationships between reproductive and hormonal factors and thyroid cancer, we conducted a population-based case-control interview study among 238 women diagnosed with thyroid cancer and a similar number of individually matched controls in Kuwait. Among the demographic variables, women with 12+ years of education had a significantly reduced risk of thyroid cancer (OR = 0.4; 95% CI: 0.2-0.8; p-trend <0.05). The average age at diagnosis (+/-SD) of thyroid cancer was 34.7 +/- 11 years. Events such as age at menarche, pregnancy, menopausal status and age at menopause were not associated with thyroid cancer. There was an association with age at last pregnancy and parity. Women who had their last pregnancy at ages > or = 30 years were at a significantly increased risk (OR = 2.1; 95% CI: 1.2-3.8); there was also a significant trend in risk with increasing age at last pregnancy. There was a modest increase in risk among women who had borne > or = 5 children (OR = 1.5; 95% CI: 0.9-2.5). A joint analysis of these factors showed that childbearing during the latter half of reproductive life had a substantial effect on the incidence of thyroid cancer; for any given level of parity, there was about a 2-fold increased risk if the age at last pregnancy was > or = 30 years. A substantial recent-birth effect, in relation to subsequent diagnosis of thyroid cancer, was observed during the second and third year after a birth (OR = 2.0; 95% CI: 1.0-4.1). In contrast, spontaneous abortion seemed to have a protective effect. There was a significant decrease in risk among women who had a miscarriage as outcome of first pregnancy (OR = 0.1; 95% CI: 0.03-0.4) and those who had experienced > or = 3 miscarriages (OR = 0.3; 95% CI: 0.1-0.8; p-trend <0.05). Overall, any female hormone use was not associated with thyroid cancer risk. New association is suggested for a history of post-partum thyroiditis (OR = 10.2; 95% CI: 2.3-44.8). These data support the hypothesis that reproductive factors and patterns may influence, or contribute to, the risk of thyroid cancer among women.

Recent advances in cytometry, cytogenetics and molecular genetics of thyroid tumours and tumour-like lesions

In this review we summarize the most recent advances of flow and image cytometry, cytogenetics and molecular genetics of tumours and tumour-like lesions of the thyroid, especially focusing on the putative relationship between nodular goitres and adenomas, the differential diagnosis of benign and malignant neoplasms and the pathogenesis and prognosis of carcinomas. Data obtained by in situ hybridization and immunohistochemical detection of proliferative markers, metal binding proteins and oncogenes, anti-oncogenes, growth factors and growth factor receptors are also used whenever appropriate.

Expression of the estrogen receptor in human thyroid neoplasms

The expression and quantitation of the estrogen receptor (ER) in human thyroid tumors were examined by biochemical, immunohistochemical, and reverse transcriptase-polymerase chain reaction (RT-PCR) techniques. For this study, neoplasms, adenomatous goiters and adjacent normal thyroid tissues were obtained from 35 patients which included 10 cases of papillary carcinomas, 17 cases of adenomas and 8 cases of adenomatous goiters. Regardless of the histopathological subtype, ER was detected in 19% (5/27) of the neoplastic tissues with the mean value of ER content of 5.0 +/- 1.3 fmol/mg protein and the mean Kd value of 0.38 +/- 0.28 nM. ER was also detected, but at a lower concentration (2.8 +/- 1.6 fmol/mg protein), in the surrounding normal tissues. There was no significant difference between the neoplasms and adenomatous goiters with respect to the incidence of ER positivity and ER content. Furthermore, ER-positive specimens, as determined by both biochemical and immunohistochemical techniques, also showed the expression of ER mRNA detected by RT-PCR method. These results demonstrate that both ER mRNA as well as ER protein are expressed in thyroid neoplasms. This suggests the possibility that estrogen may affect the tumorigenesis or the progression of some thyroid neoplasms.

Immunohistochemical study of estrogen receptor and estradiol on papillary thyroid carcinoma in young patients

We have immunohistochemically examined estrogen receptors (ER) and estradiol (E2) on papillary thyroid carcinoma in young females under the age of 25 years. The 10 young females in this study were compared with 64 females 30 years of age or older who underwent surgery for treatment of papillary thyroid carcinoma. We did not find any significant difference in the incidences of positive staining for E2 between the two groups. Of the specimens obtained from the young patients, 80% (8/10) showed positive staining for ER; this was significantly higher (P < 0.01) than that observed in patients 30 years of age or older (25%). We think that, especially in youth, estrogen may play an important role as a promoting factor. This indication needs further study.