Menstrual and reproductive factors in the risk of differentiated thyroid carcinoma in young women in France: a population-based case-control study

Prediction of cytology-histology discrepancy when Bethesda cytology reports benign results for thyroid nodules in women: with special emphasis on pregnancy

Objectives: Benign category of Bethesda classification is generally well known to carry a false-negative rate of 0-3%. The current study was designed to investigate the rate of false-negative cytology in patients who underwent thyroidectomy for presumably benign thyroid diseases. Predictive risk factors for false results and malignancy were evaluated along with cytology-histology discrepant cases.Materials and methods: Females who underwent thyroidectomy between May 2014 and December 2022 were included. Demographics, ultrasound (US) features, fine-needle aspiration (FNA) diagnosis, surgical indications and outcomes, final histology reports, risk factors, and malignancy rate were recorded. Cytology-histology discrepant cases were further evaluated for interpretation errors and risk factors. Statistical analyses were performed using Fisher's exact and Mann-Whitney U tests.Results: Of 581 women with a benign thyroid disease who underwent thyroidectomy, 91 was diagnosed as incidental carcinoma (15.6%) and most was T1a (4.9 ± 2.7 mm, 95.6%). Final histology reports revealed mostly papillary carcinoma (93.4%). Predictors of malignancy such as age, family history, previous radiation exposure, and iodine-deficient diet did not help in risk stratification (p > 0.05, for each). However, FNA taken during pregnancy was determined as a risk factor (n = 7, 7.6%, p < 0.05) since it may cause a delay in diagnosis. Cytology-histology discrepant cases were seen to be mostly due to sampling errors (45%, p < 0.05), followed by misinterpretations (37.3%, p < 0.05). There was no reason for discrepancy in 17.5%, and this was linked to inherent nature of thyroid nodule with overlapping cytologic features. Best identifiable risk factor for misinterpretation was pregnancy as well (n = 5, 14.7%, p < 0.05).Conclusions: Risk of malignancy in a presumably benign thyroid disease should not be ignored. Radiology-cytology correlation by an experienced dedicated team may help in decreasing sampling errors. Physiologic changes caused by pregnancy may shade malignant transformation in thyrocytes, and it would be appropriate to be cautious about benign FNA taken during this period.

Women consuming oral contraceptives containing cyproterone acetate and ethinylestradiol show a higher risk of thyroid cancer than nonusers

This study explored whether the risk of thyroid cancer in Asian women is associated with consumption of oral contraceptives (Diane-35). We conducted a population-based, retrospective cohort study using the Taiwan National Health Insurance Research Database. From the database, 9865 women aged 18 to 65 years who were prescribed Diane-35 between 2000 and 2012 were included in the Diane-35 group, and 39,460 women who were not prescribed Diane-35 were included in the comparison group and were frequency-matched by age and index year. Both groups were followed until 2013 to calculate the incidence of thyroid cancer. Hazard ratios (HR) and 95% confidence intervals (CI) were estimated using Cox proportional hazard model. The median (standard deviation) follow-up duration was 7.08 (3.63) and 7.04 (3.64) years in the Diane-35 and the comparison group, respectively. The incidence of thyroid cancer was 1.80-fold higher in the Diane-35 group than in the comparison group (2.72 vs 1.51 per 10,000 person-years). The cumulative incidence of thyroid cancer was significantly higher in the Diane-35 group than in the comparison group (log-rank test, P = .03). An elevated hazard ratio of thyroid cancer was observed in the Diane-35 group than in the comparison group (HR: 1.91, 95% CI: 1.10-3.30). In subgroup analysis, patients aged 30 to 39 years showed a higher hazard ratio of developing thyroid cancer after consuming Diane-35 than those in the comparison group (HR: 5.58, 95% CI: 1.84-16.91). The study provides evidence that women aged 30 to 39 years consuming Diane-35 are at increased risk of thyroid cancer. Nevertheless, a larger population with a longer follow-up may be necessary to confirm causality.

Association between breastfeeding and breast, thyroid, and cervical cancer among Korean adult women: based on the Korean Genome and Epidemiology Study

Purpose

The purpose of this study was to explore the association between breastfeeding and the prevalence of breast, thyroid, and cervical cancer among Korean adult women.

Methods

The study was a secondary analysis of data from the Korea Genome and Epidemiology Study. The final samples were 113,944 Korean women among 173,205 urban-based cohort participants collected between 2004 and 2013 for adults aged forty and over. To determine the association between female cancers and breastfeeding experience, the number of childbirth, and total breastfeeding duration, logistic regression analysis was done. The demographic characteristics, health behavior, and female history were adjusted.

Results

The prevalence of breast cancer was 1.37 times higher in the non-breastfeeding group than in the breastfeeding group. Compared to having breastfed for more than 36 months, the prevalence of thyroid cancer was 1.68 times higher at breastfeeding for 13 to 36 months, 1.67 times higher at breastfeeding for 6 to 12 months, and 2.06 times higher at breastfeeding less than 6 months. Also, the prevalence of cervical cancer was 1.54 times higher at breastfeeding for 13 to 36 months, compared to breastfeeding for more than 36 months.

Conclusion

This study found that breastfeeding experience and a longer breastfeeding duration are associated with reduced risk of breast, thyroid, and cervical cancer in Korean women. It can be used as a basis for encouraging breastfeeding, and suggests further research on modifiable factors that reduce cancer risks.

Sex Bias in Differentiated Thyroid Cancer

Differentiated thyroid cancers are more frequent in women than in men. These different frequencies may depend on differences in patient's behavior and in thyroid investigations. However, an impact on sexual hormones is likely, although this has been insufficiently elucidated. Estrogens may increase the production of mutagenic molecules in the thyroid cell and favor the proliferation and invasion of tumoral cells by regulating both the thyrocyte enzymatic machinery and the inflammatory process associated with tumor growth. On the other hand, the worse prognosis of thyroid cancer associated with the male gender is poorly explained.

Adapted dietary inflammatory index and differentiated thyroid carcinoma risk in two French population-based case-control studies

PURPOSE

Thyroid cancer is the most common endocrine cancer and its etiology is still not well understood. The aim of the present study was to assess the association between an adapted dietary inflammatory index and differentiated thyroid cancer (DTC) risk in two population-based case-control studies (CATHY and YOUNG-THYR) conducted in France.

METHODS

These studies included a total of 1321 DTC cases and 1502 controls, for which an adapted dietary inflammatory index (ADII) was computed based on food frequency questionnaires in each study separately. The association between ADII and thyroid cancer risk was assessed using logistic regression models controlling for potential confounders.

RESULTS

Higher ADII scores, corresponding to a higher pro-inflammatory potential of the diet, were associated with higher DTC risk (odds ratio (OR) for 1 standard deviation (SD) increase: 1.09, 95% confidence interval (CI): 1.01, 1.18, P: 0.03). Associations were stronger in analyses restricted to women (OR for 1-SD increase: 1.14, 95% CI 1.04, 1.25, P: 0.005), as well as in women with lower education level, current smoking, or high body mass index.

CONCLUSION

Our study suggests that a pro-inflammatory diet is associated with an increased risk of DTC, especially when combined with other inflammatory conditions such as tobacco smoking or overweight. Our findings will help better understand the role of diet-induced inflammation in DTC etiology.

Multiethnic genome-wide association study of differentiated thyroid cancer in the EPITHYR consortium

Incidence of differentiated thyroid carcinoma (DTC) varies considerably between ethnic groups, with particularly high incidence rates in Pacific Islanders. DTC is one of the cancers with the highest familial risk suggesting a major role of genetic risk factors, but only few susceptibility loci were identified so far. In order to assess the contribution of known DTC susceptibility loci and to identify new ones, we conducted a multiethnic genome-wide association study (GWAS) in individuals of European ancestry and of Oceanian ancestry from Pacific Islands. Our study included 1554 cases/1973 controls of European ancestry and 301 cases/348 controls of Oceanian ancestry from seven population-based case-control studies participating to the EPITHYR consortium. All participants were genotyped using the OncoArray-500K Beadchip (Illumina). We confirmed the association with the known DTC susceptibility loci at 2q35, 8p12, 9q22.33 and 14q13.3 in the European ancestry population and suggested two novel signals at 1p31.3 and 16q23.2, which were associated with thyroid-stimulating hormone levels in previous GWAS. We additionally replicated an association with 5p15.33 reported previously in Chinese and European populations. Except at 1p31.3, all associations were in the same direction in the population of Oceanian ancestry. We also observed that the frequencies of risk alleles at 2q35, 5p15.33 and 16q23.2 were significantly higher in Oceanians than in Europeans. However, additional GWAS and epidemiological studies in Oceanian populations are needed to fully understand the highest incidence observed in these populations.

Reproductive and menstrual factors for papillary thyroid cancer risk: A case-control study in Chinese women

BACKGROUND

Thyroid cancer (TC) is threefold more common in women than men. Reproductive and menstrual factors may be related to the onset of papillary thyroid cancer (PTC). This study aims to determine the association of reproductive and menstrual factors with PTC in Chinese females.

METHODS

A total of 335 histologically confirmed cases of PTC were recruited in this case-control study. The controls were matched for age with a deviation of ± 2 years, which conducted from September 2016 to February 2019. Logistic regression models were applied to identify the association of reproductive and menstrual factors with PTC.

RESULTS

After adjustment by some variables, early menarche age (OR ≤ 13 years vs. > 13years = 2.40, 95 % CI 1.12-5.13) and shorter lifetime breastfeeding (OR <6 months vs. ≥ 6 months = 1.99, 95 % CI 1.11-3.55) significantly increased the risk of PTC, whereas younger age at first pregnancy had a protective effect against PTC (OR ≤ 24years vs. > 24 years = 0.66, 95 % CI 0.44-0.98). There was a positive correlation between premenopausal and PTC in the lower age group (OR _{premenopausal vs. Menopause by natural} =2.34, 95 %CI 1.03-5.28).

CONCLUSIONS

Early menarche age, abortion, shorter breastfeeding duration and premenopausal may be related to the occurrence of PTC. Early age at first pregnancy and larger number of full-time pregnancies were possible to decrease the risk of PTC.

Role of DNA Repair Variants and Diagnostic Radiology Exams in Differentiated Thyroid Cancer Risk: A Pooled Analysis of Two Case-Control Studies

BACKGROUND

Given the increased use and diversity of diagnostic procedures, it is important to understand genetic susceptibility to radiation-induced thyroid cancer.

METHODS

On the basis of self-declared diagnostic radiology examination records in addition to existing literature, we estimated the radiation dose delivered to the thyroid gland from diagnostic procedures during childhood and adulthood in two case-control studies conducted in France. A total of 1,071 differentiated thyroid cancer (DTC) cases and 1,188 controls from the combined studies were genotyped using a custom-made Illumina OncoArray DNA chip. We focused our analysis on variants in genes involved in DNA damage response and repair pathways, representing a total of 5,817 SNPs in 571 genes. We estimated the OR per milli-Gray (OR/mGy) of the radiation dose delivered to the thyroid gland using conditional logistic regression. We then used an unconditional logistic regression model to assess the association between DNA repair gene variants and DTC risk. We performed a meta-analysis of the two studies.

RESULTS

The OR/mGy was 1.02 (95% confidence interval, 1.00-1.03). We found significant associations between DTC and rs7164173 in CHD2 (P = 5.79 × 10-5), rs6067822 in NFATc2 (P = 9.26 × 10-5), rs1059394 and rs699517 both in ENOSF1/THYS, rs12702628 in RPA3, and an interaction between rs7068306 in MGMT and thyroid radiation doses (P = 3.40 × 10-4).

CONCLUSIONS

Our results suggest a role for variants in CDH2, NFATc2, ENOSF1/THYS, RPA3, and MGMT in DTC risk.

IMPACT

CDH2, NFATc2, ENOSF1/THYS, and RPA3 have not previously been shown to be associated with DTC risk.

Clinical value of matrix metalloproteinase-2 and -9 in ultrasound-guided radiofrequency ablation treatment for papillary thyroid carcinoma

OBJECTIVE

This study aimed to investigate serum matrix metalloproteinase (MMP)-2 and MMP-9 levels in patients with papillary thyroid carcinoma (PTC).

METHODS

Forty-one patients with PTC undergoing ultrasound-guided radiofrequency ablation (RFA) and 56 controls were included. Serum MMP-2 and MMP-9 levels were determined by enzyme-linked immunosorbent assay before and after surgery. Potential affecting factors were evaluated by logistic regression analysis.

RESULTS

Serum MMP-2 and MMP-9 levels were significantly higher in PTC patients compared with controls, and decreased significantly after surgery. According to receiver operating characteristic curve analysis, diagnostic values for preoperative serum MMP-2 and MMP-9 levels were 82.4% and 86.6%. There was no contrast-agent perfusion in the ablation zone in 88.5% of lesions, and enhancement within or at the lesion edge in 11.4%. The volume reduction at 3 months' follow-up was >40%. Age, microcalcification, irregular shape, and lesion diameter and number were influencing factors for PTC. Age, and lesion diameter and number were independent risk factors, while calcification and morphology were protective factors.

CONCLUSION

Serum MMP-2 and MMP-9 levels have important clinical values for the diagnosis and treatment of PTC by RFA. Preoperative serum MMP-2 and MMP-9 levels, combined with other affecting factors, contribute to disease prognosis.

Risk of thyroid cancer following hysterectomy

BACKGROUND

Hysterectomy has been associated with increased thyroid cancer risk but whether this reflects a biological link or increased diagnosis of indolent cancers due to greater medical contact remains unclear.

METHODS

We recruited 730 women diagnosed with thyroid cancer and 785 age-matched population controls. Multivariable logistic regression was used to assess the association overall, and by tumour BRAF mutational status as a marker of potentially higher-risk cancers. We used causal mediation analysis to investigate potential mediation of the association by healthcare service use.

RESULTS

Having had a hysterectomy was associated with an increased risk of thyroid cancer (odds ratio [OR] = 1.45, 95 % confidence interval [CI] 1.07-1.96). When stratified by indication for hysterectomy, the risk appeared stronger for those who had a hysterectomy for menstrual disorders (OR = 1.67, 95 % CI 1.17-2.37) but did not differ by tumour BRAF status. Approximately 20 % of the association between hysterectomy and thyroid cancer may be mediated by more frequent use of healthcare services.

CONCLUSIONS

The observed increased risk of thyroid cancer among those with hysterectomy may be driven, at least partly, by an altered sex steroid hormone milieu. More frequent healthcare service use by women with hysterectomy accounts for only a small proportion of the association.

A narrative review of pregnancy after malignancies in young women that don't originate in the female genital organs or in the breast

While cancer during pregnancy and its treatment has grown to be a popular topic in recent years, little is known on how to advise patients looking to conceive or conceiving after cancer treatment. The aim of this paper is to review the available literature on the impact of pregnancy on survivors of the most common childhood cancers, brain cancer, haematological malignancies, thyroid cancer, melanomas and sarcomas. Its main objective is to be a source of information for clinicians looking to counsel patients in these delicate moments exploiting all the available literature, albeit scarce. Given the available literature, we conclude that the presence of a multidisciplinary team is of great importance in supporting the patient and her loved ones when facing pregnancy with a previous cancer diagnosis.

Menstrual, reproductive and hormonal factors and thyroid cancer: a hospital-based case-control study in China

BACKGROUND

There have been considerable studies on the effects of reproductive factors on thyroid cancer risk, while findings are inconsistent. In this analysis, we aimed to investigate the associations between menstrual, reproductive and hormonal factors with thyroid cancer occurrence in a population of Chinese women.

METHODS

Using data from a 1:1 matched case-control study performed between 2015 and 2017 in Zhejiang Province of China, a second analysis of 2261 pairs of female subjects was conducted. The possible effects for thyroid cancer were evaluated in logistic regression models by odds ratios (ORs) with 95% confidence intervals (CIs).

RESULTS

Later age at first pregnancy (for > 25 vs. ≦ 20 years, OR: 0.47, 95% CI 0.23-0.96) and longer duration of breast feeding (for 6-12 vs. ≦ 6 months, OR: 0.49, 95% CI 0.24-0.98) were significantly associated with decreased occurrence of thyroid cancer, while no trend was observed. Stratified by age at enrollment, only the association with duration of breast feeding remained significant, but limited to younger women (≦ 50 years).

CONCLUSIONS

Our results suggested that women with later age at first pregnancy or longer breast feeding duration were less likely to have thyroid cancer. These findings supported an influence role of reproductive factors in thyroid cancer risk.

Changes in the Demographic and Clinicopathological Characteristics of Thyroid Cancer: A Population-Based Investigation in Algeria, 1993-2013

Over the last three decades, the incidence of thyroid cancer has increased worldwide. The reasons for this increase remain controversial. In Algeria, however, to date, information on thyroid cancer has been limited to a hospital-based case series. We analyzed data from a population-based cohort study in Oran District, Algeria, to describe demographic and clinicopathological characteristics of patients diagnosed with thyroid cancer between 1993 and 2013. Medical records and pathology reports of thyroid cancer patients who had surgery were reviewed. Changes in demographic and clinicopathological features over the 21-year period are described. During the study period, thyroid cancer was diagnosed in 1248 women (86.5%, mean age 43.7 ± 15.2 years) and 195 men (23.4%, mean age 48.1 ± 15.9 years). Most cases (83.1% for women and 69.8% for men) sought a diagnosis following a self-neck check. The most common histologic types were papillary (58.3%), follicular (29.7%), anaplastic (4.1%), and medullary (0.8%) carcinomas. The incidence of papillary carcinomas significantly increased (p < 0.001) while the incidence of other histologic types significantly decreased over time. Tumor size overall significantly decreased (p < 0.001) while the frequency of small (≤20 mm) and larger (>20 mm) carcinomas significantly increased (p < 0.05). The frequency of thyroid cancers with capsular effractions and angioinvasions also decreased over time. Thyroid cancer incidence in Algeria has increased substantially in line with international trends with changes in clinical practice being a possible contributing factor. However, the increasing papillary-to-follicular cancer ratio may be due to changes in iodine nutrition status in Algeria. Further research, including exploration of biological and molecular features of thyroid cancer, will enable a better understanding of risk factors and etiopathogenetic mechanisms.

Correlation analysis between the pre-operative contrast-enhanced ultrasound parameters and biological characteristics of papillary thyroid carcinoma and associated risk factors for prognosis after radiofrequency ablation

The present study aimed to assess the correlation between the contrast-enhanced ultrasound (CEUS) parameters and biological characteristics of papillary thyroid carcinoma (PTC), and identify risk factors of recurrence for the prognosis after radiofrequency ablation. A total of 72 patients with PTC were included. Disease recurrence and metastasis were evaluated based on the imaging performance and laboratory tests. Perfusion parameters were recorded and compared. After biopsy, the tumor tissues were subjected to hematoxylin and eosin staining, and the expression levels of P53 and Ki67 were detected using immunohistochemistry. The association between the CEUS parameters and the expression of P53 and Ki67 was analyzed. Risk factors for disease recurrence were analyzed using logistic regression. Compared with normal tissues, PTC tissue was characterized by a slow perfusion pattern with no obvious enhancement. The peak time and intensity were lower, while the initial increasing time and mean transit time (MTT) were longer in the PTC tissue. The expression levels of P53 and Ki67 in PTC tissues were associated with age, local infiltration, lymph node metastasis and the number of lesions, but not with gender, tumor size, histological type or degree of differentiation. The initial increasing time, peak time and MTT were negatively correlated, while the peak intensity was positively correlated with the expression of P53 and Ki67 in PTC tissues. Multivariate logistic regression analysis suggested that lymph node metastasis, age, local infiltration, peak intensity and MTT were risk factors for disease recurrence. In conclusion, quantitative CEUS parameters are closely linked to the biological characteristics of PTC and may serve as indicators for the prognosis of patients.

Role of GSTM1 and GSTT1 genotypes in differentiated thyroid cancer and interaction with lifestyle factors: Results from case-control studies in France and New Caledonia

Background

GSTM1 and GSTT1 are involved in detoxification of xenobiotics, products of oxidative stress and in steroid hormones metabolism. We investigated whether GSTM1 and GSTT1 gene deletion was associated with DTC risk and explored interaction with non-genetic risk factors of DTC.

Methods

The study included 661 DTC cases and 736 controls from two case-control studies conducted in France and New Caledonia. Odds ratios (OR) and their confidence interval (CI) for DTC associated with GST genotypes, alcohol drinking, tobacco smoking, body mass index and hormonal factors were calculated using logistic regression models.

Results

Results are presented for Europeans and Melanesians combined, as no heterogeneity between groups was detected. We found that DTC risk increased with obesity and decrease with alcohol drinking. After stratification by gene deletion status, the OR for obesity was 5.75, (95%CI 2.25–14.7) among individuals with GSTT1 and GSTM1-deleted genotype, and 1.26, (95%CI 0.89–1.77) in carriers of both genes (p-interaction = 0.02). The OR for drinking ≥1 glass/week was 0.33 (95%CI 0.15–0.74) in GSTT1-null individuals while it was 1.01 (95%CI 0.67–1.52) in non-null carriers of the gene (p-interaction = 0.01). No interaction between GST genotypes and other non-genetic risk factors was detected.

Conclusion

GSTM1 and GSTT1 genotypes may modulate the DTC risk associated with BMI and alcohol consumption.

Menstrual and reproductive factors in the risk of thyroid cancer in Japanese women: the Japan Public Health Center-Based Prospective Study

The aim of this study was to evaluate the associations between menstrual and reproductive factors and thyroid cancer risk among Japanese women. A total 54 776 women aged 40-69 years completed a self-administered questionnaire, which included menstrual and reproductive history. During 1990-2012, 187 newly diagnosed cases of thyroid cancer were identified. Hazard ratios (HRs) and 95% confidence intervals (CIs) for menstrual and reproductive factors and incidence of thyroid cancer were estimated using Cox proportional hazards regression. Postmenopausal women who had natural menopause were at reduced risk of thyroid cancer than premenopausal women in the age-area-adjusted model (HR: 0.62 per 1 year increase, 95% CI: 0.39-0.99), but this association was slightly attenuated and no longer statistically significant in the multivariable-adjusted model. On analysis by menopausal status, an inverse association between age at menarche and risk of thyroid cancer was observed for premenopausal women (HR: 0.83 per 1 year increase, 95% CI: 0.70-0.98, P trend=0.03), but not for postmenopausal women. The risk of thyroid cancer increased with surgical menopause compared with natural menopause (HR: 2.34, 95% CI: 1.43-3.84). Although increasing age at menopause and duration of fertility were associated with an increased risk of thyroid cancer, this association was not observed among postmenopausal women. This study confirmed that early age at menarche for premenopausal women and surgical menopause and late age at natural menopause for postmenopausal women were associated with the development of thyroid cancer. Our results support the hypothesis that exposure to estrogens increases the risk of thyroid cancer.

Early menarche is independently associated with subclinical hypothyroidism: a cross-sectional study

Background Subclinical hypothyroidism (SH) is more frequent in females than males, with a female to male ratio ranging from 1.5 to 5 in the general population. The aim of this study was to evaluate for the first time the association of reproductive factors, particularly age at menarche, with SH risk. Materials and methods In a cross-sectional study, reproductive factors such as age at menarche, at menopause and at first birth, lactation, parity, full-term pregnancies, reproductive years, use of oral contraceptives and hormonal replacement therapy, somatometric data and insulin resistance parameters were recorded in 72 consecutive female patients with SH and 72 healthy female controls matched on age (±5 years) and date of diagnosis (±1 month). Results SH cases exhibited significantly younger age at menarche than controls (12.6 ± 1.2 vs. 13.3 ± 0.8 years, respectively, p < 0.001). Cases presented later age at first pregnancy with a lower number of full-term pregnancies (p = 0.04). Early age at menarche was independently associated with SH risk, above and beyond thyroid autoimmunity, body mass index (BMI), hip circumference (HC), homeostatic model assessment of insulin resistance and alcohol consumption [odds ratio (OR): 0.22, 95% confidence interval (CI): 0.11-0.44; p < 0.001]. Conclusions It is possible that an interplay of early exposure to estrogens, as expressed by early menarche, and induction of thyroid autoimmunity may be associated with SH risk. More prospective studies shedding light on the role of estrogens in SH are required to confirm these findings.

Fasting serum glucose, thyroid-stimulating hormone, and thyroid hormones and risk of papillary thyroid cancer: A case-control study

BACKGROUND

This study was to investigate the association of fasting serum glucose (FSG), thyroid-stimulating hormone (TSH), and thyroid hormones with papillary thyroid cancer (PTC).

METHODS

A total of 649 participants were included in this case-control study. The associations of FSG, TSH, free triiodothyronine (FT3) and free thyroxine (FT4) with PTC were estimated using an unconditional logistic regression.

RESULTS

Compared with the lowest quintile of TSH levels, odds ratios (ORs) and 95% confidence intervals (CIs) for association between PTC risk and highest quintile of TSH levels were 1.67 (95% CI, 0.99-2.83). However, this risk correlation was more significant in PTC cases with ≤1.0 cm tumor size (adjusted OR, 1.95; 95% CI, 1.08-3.54; adjusted P-trend, 0.05). The PTC risk was also inversely associated with the serum FT3 level in all participants (adjusted P-trend, 0.001), but positively associated with the serum FT4 (adjusted P-trend, 0.001) and FSG (adjusted P-trend, 0.01) levels. Among the participants without diabetes, the individuals with high FSG levels and abnormal TSH concentration had an increased PTC risk (adjusted OR, 3.38; 95% CI, 1.78-6.42).

CONCLUSION

The current study provides evidence for the association of FSG, TSH, and thyroid hormones (FT3 and FT4) with PTC risk. However, larger relative studies are needed.

The Emerging Role of Estrogens in Thyroid Redox Homeostasis and Carcinogenesis

Reactive oxygen species (ROS) are the most critical class of free radicals or reactive metabolites produced by all living organisms. ROS regulate several cellular functions through redox-dependent mechanisms, including proliferation, differentiation, hormone synthesis, and stress defense response. However, ROS overproduction or lack of appropriate detoxification is harmful to cells and can be linked to the development of several diseases, such as cancer. Oxidative damage in cellular components, especially in DNA, can promote the malignant transformation that has already been described in thyroid tissue. In thyrocyte physiology, NADPH oxidase enzymes produce large amounts of ROS that are necessary for hormone biosynthesis and might contribute to the high spontaneous mutation rate found in this tissue. Thyroid cancer is the most common endocrine malignancy, and its incidence is significantly higher in women than in men. Several lines of evidence suggest the sex hormone estrogen as a risk factor for thyroid cancer development. Estrogen in turn, besides being a potent growth factor for both normal and tumor thyroid cells, regulates different mechanisms of ROS generation. Our group demonstrated that the thyroid gland of adult female rats exhibits higher hydrogen peroxide (H₂O₂) production and lower enzymatic antioxidant defense in comparison with male glands. In this review, we discuss the possible involvement of thyroid redox homeostasis and estrogen in the development of thyroid carcinogenesis.

Estrogen receptor β upregulated by lncRNA-H19 to promote cancer stem-like properties in papillary thyroid carcinoma

Estrogen receptor β (ERβ) plays critical roles in thyroid cancer progression. However, its role in thyroid cancer stem cell maintenance remains elusive. Here, we report that ERβ is overexpressed in papillary thyroid cancer stem cells (PTCSCs), whereas ablation of ERβ decreases stemness-related factors expression, diminishes ALDH⁺ cell populations, and suppresses sphere formation ability and tumor growth. Screening estrogen-responsive lncRNAs in PTC spheroid cells, we find that lncRNA-H19 is highly expressed in PTCSCs and PTC tissue specimens, which is correlated with poor overall survival. Mechanistically, estradiol (E2) significantly promotes H19 transcription via ERβ and elevates H19 expression. Silencing of H19 inhibits E2-induced sphere formation ability. Furthermore, H19 acting as a competitive endogenous RNA sequesters miRNA-3126-5p to reciprocally release ERβ expression. ERβ depletion reverses H19-induced stem-like properties upon E2 treatment. Appropriately, ERβ is upregulated in PTC tissue specimens. Notably, aspirin attenuates E2-induced cancer stem-like traits through decreasing both H19 and ERβ expression. Collectively, our findings reveal that ERβ-H19 positive feedback loop has a compelling role in PTCSC maintenance under E2 treatment and provides a potential therapeutic targeting strategy for PTC.

Association between vitamin D deficiency and risk of thyroid cancer: a case-control study and a meta-analysis

PURPOSE

Although vitamin D is reportedly associated with various cancers, the association between vitamin D and thyroid cancer is indefinite. We aimed to investigate whether this association applies to thyroid cancer (TC).

METHODS

A total of 276 Chinese Han people were recruited in a current matched case-control study. Multivariable conditional logistic regression was computed to estimate the association between plasma 25(OH)D and papillary thyroid cancer (PTC). In addition, we searched relevant studies in PubMed and Web of Science databases before December 2017 to conduct a meta-analysis.

RESULTS

In our case-control study, plasma 25(OH)D concentration was inversely associated with PTC risk (highest tertile vs lowest tertile: adjusted OR = 0.25; 95% CI 0.10, 0.61; P_trend = 0.003). This association was independent of body mass index and physical activity (all adjusted P_interaction > 0.05). A total of 11 studies were included in the meta-analysis, among which ten studies have been published and one was our case-control study. Compared with 25(OH)D non-deficient group, the pooled OR of TC was 1.42 (95% CI 1.17, 1.73) in the deficient group. Similarly, blood 25(OH)D levels in patients with TC were tend to be lower than those in the controls (SMD = - 0.20, 95% CI - 0.36, - 0.03).

CONCLUSIONS

A high level of circulating 25(OH)D was associated with a decreased TC risk. This association has important significance in public health and should, therefore, be further studied.

Fertility Drugs Associated with Thyroid Cancer Risk: A Systematic Review and Meta-Analysis

Associations have been demonstrated between fertility drugs and a variety of hormone-sensitive carcinomas. The purpose of this study was to determine the relationship between fertility drugs used in the treatment of female infertility and the risk of thyroid cancer. To investigate the clinical significance of fertility drugs used for the treatment of female infertility and the risk associated with thyroid cancer, we performed a literature search using PubMed, MEDLINE, the Cochrane Library, the Web of Science, and EBSCOHOST for comparative studies published any time prior to July 21, 2017. The studies included women who were treated for infertility with fertility drugs, such as clomiphene citrate, gonadotropins, or other unspecified fertility agents, which reported the incidence of thyroid cancer as the main outcome. Eight studies were included in the meta-analyses. Among women with infertility, there was a significant positive association between thyroid cancer risk and the use of fertility drugs (relative risk [RR] = 1.35; 95% confidence interval [CI] 1.12–1.64; P = 0.002). Additionally, among women with infertility, the use of clomiphene citrate was associated with an increased risk of thyroid cancer compared to women who did not use fertility drugs (RR = 1.45; 95% CI 1.12–1.88; P = 0.005). After pooling results, we found that the parity status of infertile women using fertility drugs was not associated with thyroid cancer risk (RR = 0.99; 95% CI 0.61–1.58, P = 0.95). In summary, clomiphene citrate (the most commonly used fertility drug) and other fertility drugs are associated with an increased risk of thyroid cancer.

Pregnancy in papillary thyroid cancer survivors

OBJECTIVE

To evaluate “papillary thyroid carcinoma-pregnancy” interaction among cancer survivors.

MATERIAL AND METHODS

The clinical records of 8 pregnant women who received treatment for papillary thyroid cancer before their pregnancy were evaluated. Clinical features, pregnancy/perinatal outcomes and high-risk factors were compared with 45 controls who were randomly assigned from the institutional perinatal medicine database.

RESULTS

Patients in the cancer group were older than the control group (34.3 vs 29.8 years). The cesarean section rate was higher (62.5% vs 33.3%) and the APGAR scores at the 1^st and 5^th minutes were lower in the cancer group.

CONCLUSION

Management of pregnancies with papillary thyroid cancer treatment and follow-up requires a multidisciplinary approach with careful antenatal care and perinatal surveillance. Patients who have received papillary thyroid cancer treatment can safely undergo pregnancy.

Dietary habits during the 2 months following the Chernobyl accident and differentiated thyroid cancer risk in a population-based case-control study

BACKGROUND

The Chernobyl nuclear power plant accident occurred in Ukraine on April 26th 1986. In France, the radioactive fallout and thyroid radiation doses were much lower than in highly contaminated areas. However, a number of risk projections have suggested that a small excess in differentiated thyroid cancer (DTC) might occur in eastern France due to this low-level fallout. In order to investigate this potential impact, a case-control study on DTC risk factors was started in 2005, focusing on cases who were less than 15 years old at the time of the Chernobyl accident. Here, we aim to evaluate the relationship between some specific reports of potentially contaminated food between April and June 1986 - in particular fresh dairy products and leafy vegetables - and DTC risk.

METHODS

After excluding subjects who were not born before the Chernobyl accident, the study included 747 cases of DTC matched with 815 controls. Odds ratios were calculated using conditional logistic regression models and were reported for all participants, for women only, for papillary cancer only, and excluding microcarcinomas.

RESULTS

The DTC risk was slightly higher for participants who had consumed locally produced leafy vegetables. However, this association was not stronger in the more contaminated areas than in the others. Conversely, the reported consumption of fresh dairy products was not statistically associated with DTC risk.

CONCLUSION

Because the increase in DTC risk associated with a higher consumption of locally produced vegetables was not more important in the most contaminated areas, our study lacked power to provide evidence for a strong association between consumption of potentially contaminated food and DTC risk.

Parity and Risk of Thyroid Cancer: a Population-Based Study in Lithuania

An association between parity and thyroid cancer risk has been investigated in a number of independent studies but yielded contradictory findings. The aim of this study was to explore the association between parity and thyroid cancer risk. The population-based cohort study in Lithuanian was conducted. The study dataset based on the linkages between all records from the 2001 population census, all cancer incidence records from the Lithuanian Cancer Registry, and all death and emigration records from Statistics Lithuania for the period between 6 April 2001 and 31 December 2009. Cox's proportional hazards regression models were used to estimate the hazard ratios (HRs) for parity, age at first birth, number of children, place of residence, education, and age at census. The cohort of 868,105 women was followed for 8.6 years, and 1775 thyroid cancer cases were diagnosed during the study period. The significantly higher thyroid cancer risk was observed among parous women (HR = 1.45, 95% CI: 1.20, 1.75) and in women with 1, 2, and 3 children, after adjusting for the possible confounding effects of relevant demographic variables. The findings of this study are consistent with the hypothesis that parity might be associated with the risk of thyroid cancer in women.

Are dietary reports in a case-control study on thyroid cancer biased by risk perception of Chernobyl fallout?

BACKGROUND

In retrospective case-control studies performed following nuclear tests or nuclear accidents, individual thyroid radiation dose reconstructions are based on fallout and meteorological data from the residential area, demographic characteristics, and lifestyle as well as dietary information. Collecting the latter is a controversial step, as dietary declarations may be affected by the subjects' beliefs about their risk behavior. This report analyses the potential for such bias in a case-control study performed in eastern France.

METHODS

The study included 765 cases of differentiated thyroid carcinoma matched with 831 controls. Risk perceptions and beliefs of cases and controls were compared using Chi² tests and differences in dietary reports were analyzed using a two-way ANOVA.

RESULTS

In general, atmospheric pollution and living near a nuclear power plant were the two major risks that may influence thyroid cancer occurrence cited by cases and controls. When focusing in particular on the consequences of the Chernobyl accident, cases were more likely to think that the consequences were responsible for thyroid cancer occurrence than controls. Vegetable consumption during the two months after the Chernobyl accident was correlated with the status of subjects, but not to their beliefs. Conversely, consumption of fresh dairy products was not correlated with the status or beliefs of subjects.

CONCLUSION

We found no evidence of systematic bias in dietary reports according to the status or beliefs held by subjects about the link between thyroid cancer occurrence and Chernobyl fallout. As such, these dietary reports may be used in further studies involving individual dosimetric reconstructions.

Hormonal and reproductive risk factors of papillary thyroid cancer: A population-based case-control study in France

The three times higher incidence of thyroid cancer in women compared to men points to a role of female sex hormones in its etiology. However the effects of these factors are poorly understood. We analyzed the association between thyroid cancer and hormonal and reproductive factors among women enrolled in CATHY, a population-based case-control study conducted in France. The study included 430 cases of papillary thyroid cancer and 505 controls frequency-matched on age and area of residence. The odds ratios for thyroid cancer increased with age at menarche (p trend 0.05). Postmenopausal women were at increased risk, as compared to premenopausal women, particularly if menopause followed an ovariectomy, and for women with age at menopause <55years. In addition, use of oral contraceptives and menopausal hormone therapy reduced the association with thyroid cancer by about one third, and breastfeeding by 27%. Overall, these findings provide evidence that the risk of thyroid cancer increases with later age at menarche and after menopause, and decreases with use of oral contraceptives and menopausal hormone therapy. These findings confirm an implication of hormonal factors in papillary thyroid cancer risk, whose mechanisms need to be elucidated.

Female Reproductive Factors and Differentiated Thyroid Cancer

Differentiated thyroid cancer (DTC) is markedly more common in women than men, the highest female-to-male ratio being recorded during the reproductive period. This evidence has led to the suggestion that female hormonal and reproductive factors may account for the observed DTC gender disparity. This review focuses on current evidence on the risk of DTC in conjunction with major female reproductive factors, including the impact of pregnancy on DTC occurrence and progression/recurrence. Overall, studies exploring the link between the risk of DTC and menstrual and menopausal factors, oral contraceptives and/or hormone replacement therapy, showed these associations, if any, to be generally weak. Nonetheless, there is some evidence that higher levels of exposure to estrogens during reproductive years may confer an increased risk of DTC. As far as pregnancy is concerned, it is unclear whether a potential association between parity and risk of DTC actually exists, and whether it is enhanced in the short-term following delivery. A possible role for pregnancy-related factors in DTC progression has been recently suggested by some reports, the results of which are consistent with a worse outcome in the short-term of women diagnosed with DTC during gestation compared to non-pregnant control patients. Also, some progression of disease has been described in women with structural evidence of disease prior to pregnancy. However, there seems to be no impact from pregnancy in DTC-related death or overall survival. Several in vitro and animal studies have evaluated the influence of estrogens (E) and estrogen receptors (ERs) on thyroid cell proliferation. Presently available data are indicative of a role of E and ERs in thyroid cancer growth, although considerable discrepancies in respect to ER expression patterns in thyroid cancer tissues actually exist. Further studies providing more direct evidence on the possible role of E and of placental hormones and growth factors on thyroid growth may expand our knowledge on the mechanisms beyond the gender disparity of proliferative thyroid diseases.

FOXE1 Polymorphism Interacts with Dietary Iodine Intake in Differentiated Thyroid Cancer Risk in the Cuban Population

BACKGROUND

The incidence of differentiated thyroid cancer (DTC) is low in Cuba, and the contribution of dietary factors to DTC in this population has not been investigated so far. The aim of this study was to evaluate the relationship between dietary iodine intake and DTC with regard to the interaction with environmental factors or some common single nucleotide polymorphisms (SNPs), based on a case-control study carried out in Cuba.

METHODS

A total of 203 cases and 212 controls from the general population were interviewed face-to-face using the dietary intake questionnaire and the photo booklet from the E3N cohort. A specific food composition table was constructed for this study. For each parameter studied, the odds ratio (OR) was stratified on age group and sex, and further adjusted for dietary energy, smoking status, ethnic group, level of education, number of pregnancies, and body surface area.

RESULTS

The risk of DTC was significantly reduced with increasing consumption of fish (p = 0.04), but no association between total dietary iodine intake and DTC risk was evident (p = 0.7). This lack of significant association was true whatever the age, the smoking status, the dietary selenium intake, and the ethnicity (p > 0.05). DTC risk was positively and strongly associated with the number of copies in the minor allele (A) for SNP rs965513 near FOXE1 among people who consumed less iodine than the median (p = 0.005).

CONCLUSION

Overall, the majority of the studied population had an optimal dietary iodine intake. DTC risk was inversely associated with high fish consumption. Furthermore, DTC risk was positively associated with the number of copies in the minor allele (A) of rs965513 among people who consumed less iodine than the median. Because these findings are based on post-diagnostic measures, studies with pre-diagnostic dietary iodine are needed for confirmation.

Estrogen and thyroid cancer is a stem affair: A preliminary study

Gender influences Papillary Thyroid Cancer (PTC) with an incidence of 3:1 when comparing women to men with different aggressiveness. This gender discrepancy suggests some role of sex hormones in favoring the malignant progression of thyroid tissue to cancer. Estrogens are known to promote Stem Cell self-renewal and, therefore, may be involved in tumor initiation. The goals of these studies are to investigate the underlying causes of gender differences in PTC by studying the specific role of estrogens on tumor cells and their involvement within the Cancer Stem Cell (CSC) compartment. Exposure to 1nmoll^-1 Estradiol for 24h promotes growth and maintenance of PTC Stem Cells, while inducing dose-dependent cellular proliferation and differentiation following Estradiol administration. Whereas mimicking a condition of hormonal imbalance led to an opposite phenotype compared to a continuous treatment. In vivo we find that Estradiol promotes motility and tumorigenicity of CSCs. Estradiol-treated mice inoculated with Thyroid Cancer Stem Cell-enriched cells developed larger tumor masses than control mice. Furthermore, Estradiol-pretreated Cancer Stem cells migrated to distant organs, while untreated cells remained circumscribed. We also find that the biological response elicited by estrogens on Papillary Thyroid Cancer in women differed from men in pathways mediated. This could explain the gender imbalance in tumor incidence and development and could be useful to develop gender specific treatment of (PTC).

Recreational Physical Activity and Differentiated Thyroid Cancer Risk: A Pooled Analysis of Two Case-Control Studies

PURPOSE

Physical activity has been hypothesized to influence cancer occurrence through several mechanisms. To date, its relation with thyroid cancer risk has been examined in relatively few studies. We pooled 2 case-control studies conducted in Cuba and Eastern France to assess the relationship between self-reported practice of recreational physical activity since childhood and thyroid cancer risk.

METHODS

This pooled study included 1,008 cases of differentiated thyroid cancer (DTC) matched with 1,088 controls (age range 9-35 and 17-60 years in the French and Cuban studies, respectively). Risk factors associated with the practice of recreational physical activity were estimated using OR and 95% CI. Logistic regressions were stratified by age class, country, and gender and were adjusted for ethnic group, level of education, number of pregnancies for women, height, BMI, and smoking status.

RESULTS

Overall, the risk of thyroid cancer was slightly reduced among subjects who reported recreational physical activity (OR = 0.8; 95% CI 0.5-1.0). The weekly frequency (i.e. h/week) seems to be more relevant than the duration (years).

CONCLUSION

Long-term recreational physical activity, practiced since childhood, may reduce the DTC risk. However, the mechanisms whereby the DTC risk decreases are not yet entirely clear.

Spatiotemporal Co-existence of Female Thyroid and Breast Cancers in Hangzhou, China

Thyroid and breast cancers (TC, BC) are common female malignant tumors worldwide. Studies suggest that TC patients have a higher BC risk, and vice versa. However, it has not been investigated quantitatively if there is an association between the space-time TC and BC incidence distributions at the population level. This work aims to answer this question. 5358 TC and 8784 BC (female) cases were diagnosed in Hangzhou (China, 2008-2012). Pearson and Spearman rank correlation coefficients of the TC and BC incidences were high, and their patterns were geographically similar. The spatiotemporal co-existence of TC and BC distributions was investigated using the integrative disease predictability (IDP) criterion: if TC-BC association is part of the disease mapping knowledge bases, it should yield improved space-time incidence predictions. Improved TC (BC) incidence predictions were generated when integrating both TC and BC data than when using only TC (BC) data. IDP consistently demonstrated the spatiotemporal co-existence of TC and BC distributions throughout Hangzhou (2008-2012), which means that when the population experiences high incidences of one kind of cancer attention should be paid to the other kind of cancer too. The strength of TC-BC association was measured by the IDP coefficients and incidence prediction accuracy.

A review on thyroid cancer during pregnancy: Multitasking is required

Thyroid cancer is the second most common cancer diagnosed during pregnancy after breast cancer. The goal of management is to control malignancy and prevent maternal and fetal complications as a result of maternal hypothyroidism. The role of female sex hormones as an etiologic factor was investigated, with no clear association. Pregnancy can cause an increase in size of a previously existed thyroid nodule through the structural similarity between TSH and BHCG, and the normally expressed estrogen receptors on thyroid gland cells. Effect of pregnancy on development and prognosis of differentiated thyroid malignancies (papillary and follicular) has also been studied. The prognosis of thyroid cancer is not worse in patients diagnosed during pregnancy or those who got pregnant after curative treatment. Termination of pregnancy is not indicated at all, surgery can be delayed till after delivery except in rapidly growing aggressive tumors. While radioactive iodine ablation is absolutely contra-indicated, the new systemic therapies are not well studied during pregnancy. However, almost all these new agents are classified as FDA category C or D and are better to be avoided. The effect of pregnancy on other types of thyroid cancer (medullary and anaplastic thyroid tumors) is not well studied because of very low incidence with pregnancy. The endocrinological management of thyroid cancer during pregnancy is of utmost importance. The hypothyroidism after total thyroidectomy can cause fetal hypothyroidism. Therefore, the management of thyroid cancer related to pregnancy needs a multidisciplinary team.

Parity and thyroid cancer risk: a meta-analysis of epidemiological studies

Although observational studies have assessed the relationship between parity and thyroid cancer risk, the findings are inconsistent. To quantitatively assess the association, we conducted a systematic review and meta-analysis. PubMed and Embase were searched up to January 2015. Prospective or case-control studies that evaluated the association between parity and thyroid cancer risk were included. We used the fixed-effects model to pool risk estimates. After literature search, 10 prospective studies, 12 case-control studies and 1 pooled analysis of 14 case-control studies including 8860 patients were identified. The studies had fair methodological quality. Pooled analysis suggested that there was a significant association between parity and risk of thyroid cancer (RR for parous versus nulliparous: 1.09, 95% CI 1.03-1.15; I2=33.4%). The positive association persisted in almost all strata of subgroup analyses based on study design, location, study quality, type of controls, and confounder adjustment, although in some strata statistical significance was not detected. By evaluating the number of parity, we identified that both parity number of 2 versus nulliparous and parity number of 3 versus nulliparous demonstrated significant positive associations (RR=1.11, 95% CI 1.01-1.22; I2=31.1% and RR=1.16, 95% CI 1.01-1.33; I2=19.6% respectively). The dose-response analysis suggested neither a non-linear nor linear relationship between the number of parity and thyroid cancer risk. In conclusion, this meta-analysis suggests a potential association between parity and risk of thyroid cancer in females. However, the lack of detection of a dose-response relationship suggests that further studies are needed to better understand the relationship.

Breastfeeding and thyroid cancer risk in women: A dose-response meta-analysis of epidemiological studies

BACKGROUND & AIMS

The association between breastfeeding and thyroid cancer risk is not consistent from epidemiological studies. To better clarify the association including assessing a potential dose-response relationship, we conducted a comprehensive meta-analysis.

METHODS

We searched PubMed (MEDLINE) up to November 2015 for prospective studies or case-control studies that evaluated the association between breastfeeding and risk of thyroid cancer. Effect estimates were pooled using a fixed-effects model.

RESULTS

Nine reports (2 prospective studies, 6 case-control studies and 1 pooled analysis of 14 case-control studies) involving 2423 cases and 350,081 non-cases were identified. After pooling relevant studies, there was a significant inverse association between ever breastfeeding and risk of thyroid cancer (RR = 0.91, 95% CI 0.83-0.99), with minor heterogeneity (I(2) = 10.1%). The dose-response analysis revealed a significant linear relationship between the duration of breastfeeding and risk of thyroid cancer. The summary RR for an increment of 1 month of breastfeeding with risk of thyroid cancer was 0.983 (95% CI 0.98-0.99). When focusing on cohort studies, a more prominent linear dose-response relationship was detected, with the combined RR for every increment of 1 month of breastfeeding to be 0.965 (95% CI 0.96-0.97).

CONCLUSIONS

This meta-analysis suggests that breastfeeding is potentially inversely associated with thyroid cancer risk. Also longer duration of breastfeeding may further decreases thyroid cancer risk. If validated in large-scale prospective studies, our findings may have implications for impacting women's decision in breastfeeding.

Anthropometric Risk Factors for Differentiated Thyroid Cancer in Young Men and Women From Eastern France: A Case-Control Study

The incidence of thyroid cancer has risen over the past decade, along with a rise in obesity. We studied the role of anthropometric risk factors for differentiated thyroid cancer at the time of diagnosis and at age 20 years in a case-control study conducted in eastern France between 2005 and 2010. The study included 761 adults diagnosed with differentiated thyroid cancer before 35 years of age between 2002 and 2006. They were matched with 825 controls from the general population. Odds ratios were calculated using conditional logistic regression models and were reported for all participants, those with papillary cancer only, and women only. The risk of thyroid cancer was higher for participants with a high body surface area (BSA), great height, or excess weight and for women with a high body fat percentage. Conversely, no significant association was found between body mass index and the risk of thyroid cancer. In the present study, we provide further evidence of the role of BSA and excess weight in the risk of thyroid cancer. These epidemiologic observations should be confirmed by further exploration of the biological mechanisms responsible for the associations of obesity and BSA with thyroid cancer.

Linear reduction in thyroid cancer risk by oral contraceptive use: a dose-response meta-analysis of prospective cohort studies

STUDY QUESTION

Is there an association between oral contraceptive (OC) use and thyroid cancer risk in females?

SUMMARY ANSWER

OC use is inversely associated with the risk of thyroid cancer in females.

WHAT IS KNOWN ALREADY

OC use may be relevant to the risk of thyroid cancer as suggested by some epidemiological studies. However, the findings are inconsistent regarding the effect direction and size.

STUDY DESIGN, SIZE, DURATION

This systematic review and meta-analysis included a total of 1906 patients from about 1.3 million individuals who had participated in 9 prospective cohort studies. The follow-up length ranged 7.5-15.9 years.

PARTICIPANTS/MATERIALS, SETTING, METHODS

PubMed (MEDLINE) was searched through to January 2015 for eligible studies. References of relevant review articles were also manually screened. Prospective cohort studies that evaluated the association between OC use and thyroid cancer risk were included. Study characteristics including patients' characteristics, length of the follow-up and risk estimates were extracted. The quality of the studies was also assessed.

MAIN RESULTS AND THE ROLE OF CHANCE

The included studies were of high methodological quality according to the Newcastle-Ottawa Quality Assessment Scale. After pooling risk estimates from all the studies, there was a significant inverse association between the longest versus shortest duration of OC use and the risk of thyroid cancer [relative risk (RR) = 0.84, 95% confidence interval (CI) 0.73-0.97], with no considerable heterogeneity (I(2) = 26.1%). There was no significant publication bias. The significant association persisted in the subgroup of high-quality studies (RR = 0.84, 95% CI 0.72-0.97). By dose-response analysis, there was a linear relationship (P = 0.0001) between the duration of OC use and thyroid cancer risk. The summary RR for an increment of 1 year of OC use was 0.96 (95% CI 0.94-0.98), with no significant heterogeneity.

LIMITATIONS, REASONS FOR CAUTION

Individual patient data were unavailable for a more accurate estimation.

WIDER IMPLICATIONS OF THE FINDINGS

These results indicate that OC use may decrease the risk of thyroid cancer in females. This may have implications for women's decisions regarding the use of OC.

STUDY FUNDING/COMPETING INTERESTS

No funding was involved for this study. No conflicts of interest are declared.

Impact of estrogen and progesterone receptor expression on the clinical and molecular features of papillary thyroid cancer

BACKGROUND

Thyroid cancer is highly prevalent in women during the fertile age, which suggests a possible impact of hormonal and reproductive factors.

METHODS

We studied the expression of estrogen receptor α (ERα or ESR1) and progesterone receptor (PR or PGR) in 182 female and male patients with papillary thyroid cancer and correlated it to clinical and molecular features.

RESULTS

ERα and PR expression was found in 66.5 and 75.8% of patients respectively and was significantly correlated with larger tumor size and with a non-incidental diagnosis. Moreover, a trend toward a higher prevalence of local metastases was observed in ER- and PR-expressing tumors, which possibly indicates a more aggressive behavior. Interestingly, the occurrence of the 'receptor conversion' phenomenon, which has already been reported to have a negative prognostic effect in breast cancer, was demonstrated for the first time in thyroid tumors. Indeed, almost all of the ERα-positive primary tumors analyzed had ERα-negative metastatic lymph nodes. At the genetic analyses, BRAF(V600E) mutation was detected in 23.2% of the tumors and had a higher prevalence in larger tumors and in those with a stronger ERα or PR staining.

CONCLUSIONS

The whole of the findings reported in the present study argue for an association between ERα and PR sex hormone receptor expression and a more aggressive presentation. Although no impact on outcome was found, the evaluation of ERα and PR receptor expression could add insights into the biological behavior of tumors and could modify the follow-up, particularly in fertile women affected with persistent disease.