The aetiology of thyroid tumours

Curcumin induces endoplasmic reticulum stress-associated apoptosis in human papillary thyroid carcinoma BCPAP cells via disruption of intracellular calcium homeostasis

BACKGROUND

Thyroid cancer is the most common endocrine tumor. Our previous studies have demonstrated that curcumin can induce apoptosis in human papillary thyroid carcinoma BCPAP cells. However, the underlined mechanism has not been clearly elucidated. Endoplasmic reticulum (ER) is a major organelle for synthesis, maturation, and folding proteins as well as a large store for Ca. Overcoming chronically activated ER stress by triggering pro-apoptotic pathways of the unfolded protein response (UPR) is a novel strategy for cancer therapeutics. Our study aimed to uncover the ER stress pathway involved in the apoptosis caused by curcumin.

METHODS

BCPAP cells were treated with different doses of curcumin (12.5-50 μM). Annexin V/PI double staining was used to determine cell apoptosis. Rhod-2/AM calcium fluorescence probe assay was performed to measure the calcium level of endoplasmic reticulum. Western blot was used to examine the expression of ER stress marker C/EBP homologous protein 10 (CHOP) and glucose-regulated protein 78 (GRP78). X-box binding protein1 (XBP-1) spliced form was examined by reverse transcriptase-polymerase chain reaction (RT-PCR).

RESULTS

Curcumin significantly inhibited anchorage-independent cell growth and induced apoptosis in BCPAP cells. Curcumin induced ER stress and UPR responses in a dose- and time-dependent manner, and the chemical chaperone 4-phenylbutyrate (4-PBA) partially reversed the antigrowth activity of curcumin. Moreover, curcumin significantly increased inositol-requiring enzyme 1α (IRE1α) phosphorylation and XBP-1 mRNA splicing to induce a subsets of ER chaperones. Increased cleavage of activating transcription factor 6 (ATF6), which enhances expression of its downstream target CHOP was also observed. Furthermore, curcumin induced intracellular Ca influx through inhibition of the sarco-endoplasmic reticulum ATPase 2A (SERCA2) pump. The increased cytosolic Ca then bound to calmodulin to activate calcium/calmodulin-dependent protein kinase II (CaMKII) signaling, leading to mitochondrial apoptosis pathway activation. Ca chelator BAPTA partially reversed curcumin-induced ER stress and growth suppression, confirming the possible involvement of calcium homeostasis disruption in this response.

CONCLUSIONS

Curcumin inhibits thyroid cancer cell growth, at least partially, through ER stress-associated apoptosis. Our observations provoked that ER stress activation may be a promising therapeutic target for thyroid cancer treatment.(Figure is included in full-text article.).

Diet and Epithelial Cancer of the Thyroid Gland

Enhanced secretion of thyroid stimulating hormone (TSH) has been linked with increased risk of thyroid carcinoma. Diet can increase TSH secretion in various ways: 1) low iodine intake, 2) high goitrogen intake, especially in subjects living in iodine-deficiency areas and 3) direct stimulation of anterior pituitary gland. Excessive iodine intake, however, has also been shown to increase risk of goitre and, perhaps, also thyroid carcinoma. Epidemiological evidence on the role of diet in the etiology of thyroid carcinoma is reviewed here. Ad hoc studies in affluent countries are few and often conflicting. A case-control study conducted in the North of Italy suggests that perhaps dietary aspects other than iodine or goitrogens (i.e. fresh fruit and vegetables and animal fat) may be involved.

Euthyroid athyroxinemia - a novel endocrine syndrome

A 55-year-old female was referred with abnormal thyroid function tests (TFTs); the free thyroxine level (FT4) was undetectable <3.3 pmol/L (normal: 7.9–14.4), while her FT3, TSH and urinary iodine levels were normal. She was clinically euthyroid with a large soft lobulated goitre that had been present for more than thirty years. She received an injection of recombinant human TSH (rhTSH) following which there was a progressive rise of the FT3 and TSH levels to 23 pmol/L and >100 mIU/L respectively at 24 h, The FT4 however remained undetectable throughout. Being on thyroxine 100 µg/day for one month, her FT4 level increased to 15 pmol/L and TSH fell to 0.08 mIU/L. Four years earlier at another hospital, her FT4 level had been low (6.8 pmol/L) with a normal TSH and a raised Tc-99 uptake of 20% (normal<4%). We checked the TFTs and Tc-99 scans in 3 of her children; one was completely normal and 2 had euthyroid with soft lobulated goitres. Their Tc-99 scan uptakes were raised at 17% and 15%, with normal TFTs apart from a low FT4 7.2 pmol/L in the son with the largest thyroid nodule. This is a previously unreported form of dyshormonogenesis in which, with time, patients gradually lose their ability to synthesize thyroxine (T4) but not triiodothyroxine (T3).

CBX7 Expression in Oncocytic Thyroid Neoplastic Lesions (Hürthle Cell Adenomas and Carcinomas)

BACKGROUND

Previous analysis of CBX7 expression in a large number of thyroid adenoma and carcinoma samples revealed a progressive reduction of CBX7 levels that was well related with the malignant grade of thyroid neoplasias. Hürthle cell tumors are unusual thyroid neoplasms characterized by the presence of particular cells called oncocytes.

OBJECTIVES

In order to develop new tools for a more accurate diagnosis of Hürthle cell tumors of the thyroid, we evaluated CBX7 protein levels to verify the possible presence of an expression signature.

METHODS

CBX7 expression was evaluated by immunohistochemistry in a panel of thyroid tissue sections including normal thyroids, goiters, follicular adenomas and oncocytic lesions.

RESULTS

CBX7 expression was low or null in 68% of Hürthle adenomas, whereas it was comparable to normal thyroid tissue in Hürthle hyperplasias and follicular adenomas.

CONCLUSIONS

Reduced expression of CBX7 suggests a more aggressive identity of Hürthle adenomas with respect to non-Hürthle ones.

Modifications in the papillary thyroid cancer gene profile over the last 15 years

BACKGROUND

Evidence for an increased prevalence of BRAF(V600E) mutations has been documented in recent decades. The aim of this study was to evaluate the prevalence of both RET/PTC rearrangements and BRAF(V600E) mutations in an Italian cohort of papillary thyroid carcinoma (PTC) patients followed at the Endocrine Units of Pisa, Milano, and Perugia from 1996-2010.

PATIENTS AND METHODS

In total, 401 PTC patients were examined and grouped according to the time of surgery: group 1, 1996-2000; group 2, 2001-2005; and group 3, 2006-2010. Patients were analyzed for clinical, pathological, and molecular features. In parallel, the molecular characteristics of 459 PTC from Sicily were studied.

RESULTS

The genetic profiles of the three groups were significantly different (P < 0.0001). In particular, the frequency of RET/PTC rearrangements decreased from 1996-2010, occurring in 33 of 100 (33%) of the patients in group 1, 26 of 148 (17%) in group 2, and 15 of 153 (9.8%) in group 3. The incidence of BRAF(V600E) mutations increased over the same period, from 28% in group 1 (28 of 100) to 48.9% in group 2 (73 of 148) and 58.1% in group 3 (89 of 153). A consistent increase in BRAF(V600E) prevalence was observed in the Sicilian group (P < 0.0001). Moreover, a statistically significant increase in the mean age at diagnosis and decrease in tumor size over the study period was observed.

CONCLUSION

The genetic profile of PTC changed over the last 15 yr, with a significant decrease in the prevalence of RET/PTC rearrangements and an increase in BRAF(V600E) mutations. In addition, the mean age at diagnosis increased and tumor size decreased over the study period.

Molecular pathogenesis of follicular cell derived thyroid cancers

Thyroid cancers are the most common endocrine malignancy. Radiation exposure, family history of thyroid cancer and some inherited conditions are the most important predisposing factors for the development of thyroid cancer. Three mitogenic signalling pathways have been described in the thyroid cell, which are influenced by various stimulatory and inhibitory hormones, growth factors and neurotransmitters. Various proto-oncogenes and oncogenes like ras, braf, trk, met and RET also play a role in the signal transduction systems. Two theories have been described in thyroid cancer pathogenesis, the foetal cell carcinogenesis theory and the more common, multistep carcinogenesis theory. The multistep carcinogenesis theory is now the accepted model in many human cancers, including thyroid cancer. The early events of tumour formation are the consequence of activation of either various growth factors or the proto-oncogenes like ras, met or ret. This results in the formation of differentiated thyroid cancers like the papillary, follicular or Hurthle cell cancers. The later stages of tumour formation involve further activation of proto-oncogenes and loss or inactivation of tumour suppressor genes like p53. Based on this theory, follicular carcinomas are generated from follicular adenomas and papillary carcinomas from precursor cells generated from thyrocytes. Anaplastic carcinoma may develop from papillary or follicular carcinoma by dedifferentiation. In this review article, we highlight the molecular pathogenesis of thyroid tumours.

Association of high iodine intake with the T1799A BRAF mutation in papillary thyroid cancer

CONTEXT

Epidemiological studies have indicated that high iodine intake might be a risk factor for papillary thyroid cancer (PTC), which commonly harbors the oncogenic T1799A BRAF mutation.

OBJECTIVE

The objective of the study was to investigate the relationship between BRAF mutation in PTC and iodine intake in patients.

SUBJECTS AND METHODS

We analyzed and compared the prevalences of the T1799A BRAF mutation in classical PTC of 1032 patients from five regions in China that uniquely harbor different iodine contents in natural drinking water, ranging from normal (10-21 microg/liter) to high (104-287 microg/liter). The BRAF mutation was identified by direct DNA sequencing.

RESULTS

The prevalence of BRAF mutation was significantly higher in any of the regions with high iodine content than any of the regions with normal iodine content. Overall, BRAF mutation was found in 387 of 559 PTC with high iodine content (69%) vs. 252 of 473 PTC with normal iodine content (53%), with an odds ratio of 1.97 (95% confidence interval 1.53-2.55) for the association of BRAF mutation with high iodine content (P < 0.0001). In addition, clinicopathological correlation analysis, the largest one of its type ever, showed that BRAF mutation was significantly associated with extrathyroidal invasion, lymph node metastasis, and advanced tumor stages of PTC.

CONCLUSIONS

High iodine intake seems to be a significant risk factor for the occurrence of BRAF mutation in thyroid gland and may therefore be a risk factor for the development of PTC. This large study also confirmed the association of BRAF mutation with poorer clinicopathological outcomes of PTC.

Chromosomal imbalances associated with anaplastic transformation of follicular thyroid carcinomas

The genetic alterations that underlie the progression of follicular thyroid carcinoma towards anaplasia are still largely uncharacterised. We compared the Comparative Genomic Hybridization (CGH) profiles of 20 follicular (FTCs), 12 poorly differentiated (PDTCs) and seven anaplastic thyroid carcinomas (ATCs), in order to identify the chromosomal imbalances potentially associated with cancer progression. We found: (i) when considering that a ‘direct’ transformation of FTC towards anaplasia occurs, the defined significantly important alterations were the increase of gains at 3q (P<0.05) and 20q (P<0.01), and the increase of losses at 7q (P<0.05) and Xp (P<0.01); (ii) regarding poorly differentiated carcinomas as an intermediate independent entity in the anaplastic transformation of follicular cancers, evidenced as important alterations towards anaplasia, were the proportional decrease in copy sequences at 7p, 7q, 12q and 13q resulting from the significant decrease of DNA gains at 7p and 12q (P<0.05), and the significant increase of losses at 7q and 13q (P<0.05). These results unveil the chromosomal regions where genes of interest in thyroid anaplastic transformation are to be located, and demonstrate that different gene dosage copy sequence imbalances are associated to the ‘direct’ pathway of transformation of follicular into anaplastic cancers and to the progressive FTC → PDTC → ATC pathway.

Chromosome imbalances in thyroid follicular neoplasms: a comparison between follicular adenomas and carcinomas

The underlying genetic events associated with follicular thyroid tumorigenesis are still ill defined. In this study, we performed a screening for chromosome imbalances by comparative genomic hybridization (CGH) in a group of 12 follicular adenomas (FAs) and 20 follicular carcinomas (FTCs) previously characterized by conventional cytogenetics and flow cytometry analysis. In general, a great similarity was observed between the CGH profiles of the FAs and FTCs. In both benign and malignant tumors, a combination of gains affecting 5, 7, 12, 17, 19, and 20 was observed. Chromosome 7 was the most frequently affected chromosome, with three regions of consensus gains: 7p11-12, 7q11.3-q21, and 7q31. Recurrent gains of chromosomes 5 and 12 involved 5p11, 5p15, 5q13-q22, 5q21-q23, 12p11, and 12q11-q12. DNA sequence losses were also observed in both tumor groups. Chromosomal arms deleted in at least five of the neoplasms were (in order of frequency): in adenomas, 15q, 2p/2q, 3q, 6p/6q, 11q, and 22q; and in FTCs, 3p, 2p, 8q, 1p, 2q, 3q, 6q, 8p, 9p, 11q, 13q, 6p, and 18q. The statistical evaluation of the CGH data demonstrated that 15q loss was significantly associated with FA. Two regions of minimal common loss were defined by CGH at 15: 15q11-q21 and 15q26-qter. The identification of these regions provides a basis for further molecular studies.

Pituitary lactotroph adenomas develop after prolonged lactotroph hyperplasia in dopamine D2 receptor-deficient mice

Tuberoinfundibular dopamine tonically inhibits PRL expression and secretion from the pituitary gland by the activation of dopamine D2 receptors (D2R) localized on lactotrophs. Mutant female mice that lack D2Rs have persistent hyperprolactinemia but also develop extensive hyperplasia of pituitary lactotrophs and peliosis of the adenohypophysis at 9 to 12 months of age, while age-matched male D2R-deficient mice have no morphologic adenohypophysial lesion. We now report that both female and male D2R-deficient mice 17 to 20 months of age develop pituitary lactotroph adenomas. Of 12 aged female mice examined, all developed monohormonal PRL-immunoreactive neoplasms that had a characteristic juxtanuclear Golgi pattern of PRL staining and loss of the reticulin fiber network. Several of these adenomas were 50-fold larger than normal glands with marked suprasellar extension and invasion of brain but no gross evidence of distant metastases. They also had striking peliosis that was more marked than the lesion seen in the hyperplastic pituitaries of the younger females. These findings demonstrate that a chronic loss of neurohormonal dopamine inhibition promotes the hyperplasia-neoplasia sequence in adenohypophysial lactotrophs. Our results are analogous to previous data indicating that protracted stimulation of adenohypophysial cells by hormones or growth factors results in proliferation with initial hyperplasia followed by the development of neoplasia. Six aged male D2R-deficient mice had slightly enlarged anterior pituitaries similar in size to normal female glands. However, each case exhibited multifocal, microscopic lactotroph adenomas with strong nuclear immunoreactivity for estrogen receptors and Pit-1 transcription factor. The unexpected development of adenomas in males without preexisting or concomitant hyperplasia suggests that prolonged loss of dopamine inhibition may also cause neoplasia by distinct cellular mechanisms in male and female animals.

Reverse transcriptase-polymerase chain reaction analysis of thyrocyte-relevant genes in fine-needle aspiration biopsies of the human thyroid

Currently, fine-needle aspiration cytology is a valuable tool in the routine diagnosis of suspicious thyroid nodules. We present a very sensitive method for the molecular analysis of the expression of several genes important for normal thyroid function in parallel to the cytological diagnosis. We adapted reverse transcriptase polymerase chain reaction (RT-PCR) to amplify thyroid-typical mRNAs in samples of thyroid carcinoma cells as small as those obtained by fine-needle aspiration biopsy (FNAB), ie, 100-1000 cells, and applied this procedure to four routinely taken FNABs. Gene products such as thyroglobulin (Tg), thyroid-stimulating hormone-receptor (TSHr), sodium/iodide-symporter (NIS), type I iodothyronine-5'-deiodinase (DI), and type II iodothyronine-5'-deiodinase (DII) were analyzed. To establish RT-PCR protocols, serial dilutions of follicular thyroid carcinoma cells, FTC-133, which express these genes at low levels, were initially used for RNA isolation. Successful RNA isolation and reverse transcription were checked by the amplification of beta-actin mRNA. We detected the mRNAs coding for Tg in as little as 10 cells, for NIS in 100 cells, and for TSHr, DI, and DII in 10,000 cells. After preparing cytological smears of four routinely taken FNABs, all above-mentioned thyroid-typical mRNAs were observed by using the material remaining in the needle for RNA isolation followed by RT-PCR. This method offers the possibility of obtaining two different types of information from the same routinely taken thyroid FNAB: the cytological diagnosis and the expression pattern of several diagnostically relevant genes. Therefore, a more specific diagnosis could be rendered in the preoperative state, and may lead to more specific therapy.

Characteristics of differentiated thyroid carcinoma in children and adolescents with respect to age, gender, and histology

BACKGROUND

Because of its rarity there have been only a few detailed studies on differentiated thyroid carcinoma (DTC) in children. The current investigation was undertaken to assess the characteristics of DTC with respect to age, gender, and histology in children and adolescents.

METHODS

In a questionnaire-based survey, data from 114 children and adolescents with DTC (age range, 3-18 years) was collected from 65 clinical institutions in Germany. Characteristics of 80 females and 34 males were evaluated and the influence of age, gender, histology, multicentric growth, tumor stage, and lymph node involvement on distant metastases was tested using multivariate discriminant analysis. Comparison between groups was performed using the Student's t test and chi-square test. Correlation between incidence and age was assessed by linear regression analysis.

RESULTS

The overall incidence of thyroid carcinoma in females was higher than in males, with a peak of female/male ratio occurring at puberty. The incidence of DTC correlated with age in females < 16 years (correlation coefficient [r] = 0.84; P = 0.0006), which was more pronounced in children with papillary thyroid carcinoma (PTC) (r = 0.83; P = 0.006) but not in those with follicular thyroid carcinoma (FTC) (r = 0.20; P = 0.16). FTC was associated with less advanced disease (P = 0.009), fewer lymph nodes involved (P = 0.007), and fewer metastases (P = 0.02) compared with PTC. Males tended to have a higher risk for distant metastases. However, statistical analysis failed to reach a level of significance (P = 0.08). Multivariate analysis revealed tumor stage as the only powerful factor (P = 0.02) correlated with distant metastasis.

CONCLUSIONS

The incidence of PTC shows a marked increase in females with the highest female/male ratio occurring at puberty. Childhood thyroid carcinoma frequently is associated with lymph node involvement, distant metastases, and extrathyroidal tumor infiltration. In children FTC appears to be less aggressive than PTC. Advanced local-regional extension stage appears to be the most powerful factor influencing the risk for distant metastases in children.

Dyshormonogenetic Goiter: A Clinicopathologic Study of 56 Cases

Dyshormonogenetic goiters (DG) are genetically determined thyroid hyperplasias due to enzyme defects in thyroid-hormone synthesis. We report 56 cases of DG occurring in 34 females and 22 males. The patients age ranged from newborn to 52 yr (median 16), 75% of the cases occurring before the age of 24. All patients presented with clinically evidence of goiter except for two patients that were diagnosed at autopsy. Hypothyroidism was documented before the histological diagnosis was made in 36 patients (64%). The thyroid gland was enlarged and multinodular in all cases, weighing up to 600g. Microscopically, the most common alteration consisted of markedly cellular nodules exhibiting a variety of architectural appearances, the solid and/or microfollicular patterns predominating. Papillary proliferations and an insular growth pattern were also present. Fibrosis was a common finding; in some instances it was very conspicuous, resulting in irregularities at the edge of the nodules simulating capsular invasion. Other constant features included marked nuclear atypia and minimal amount of colloid. In 18% of the cases, the degree of hyperplasia and atypia were such as to result in a mistaken diagnosis of follicular, papillary, medullary, or undifferentiated carcinoma. Three of the glands contained incidental small neoplasms fulfilling the criteria of papillary microcarcinoma; one of them was multicentric. The presence in a thyroid gland of the combination of these morphologic features should suggest the diagnosis of dyshormonogenetic goiter. The only other condition we are aware of that can result in a similar microscopic picture is iatrogenic goiter resulting from the administration of antithyroidal agents.

Double minutes in the papillary thyroid cancer cell line PTC-1113A

The cell line PTC-1113A was established from a metastasizing recurrent papillary thyroid cancer. The cell line was growing as monolayer and showed a complex karyotype with chromosome numbers ranging from 30 to 140/metaphase. A proportion of metaphases contained double minutes and/or pulverized chromosomes. Extrachromosomal DNA seemed to originate from a B-group chromosome. A chromosome 4 painting probe hybridized to extrachromosomal material, representing double minutes (dmin) and possibly minutes. In addition, fluorescence in situ hybridization (FISH) with the chromosome 4 library detected a translocation chromosome and a pulverized chromosome originating from chromosome 4. PTC-1113A is, to our knowledge, the single papillary thyroid cancer cell line demonstrating evidence of gene amplification.

Proto-RET is rearranged in the new human papillary thyroid cancer cell line PTC-1113A

The receptor tyrosine kinase proto-RET is believed to contribute to thyroid oncogenesis by activation of its tyrosine kinase either by point mutation or rearrangement. The papillary thyroid cancer cell lines PTC-1113A, L, and R were established from a recurrent thyroid cancer and its metastases. The rearrangement of the proto-ret oncogene in the cell line PTC-1113A is demonstrated by Southern analysis utilizing the probe for rearranged ret that encodes the fusion protein H4/tyrosine kinase. In contrast, rearranged ret alleles were not found in the cell lines that developed from metastases, nor in DNA isolated from the recurrent tumor. The cell line PTC-1113A may represent a population of tumor cells that gained a growth advantage due to rearranged ret. This is the second human thyroid cancer cell line harboring rearranged ret, and may serve to study the function of ret activation in thyroid cancers.

Cytogenetics and molecular genetics of carcinomas arising from thyroid epithelial follicular cells

Cytogenetic and molecular analyses of thyroid tumors have indicated that these neoplasms represent a good model for analyzing human epithelial cell multistep carcinogenesis. They comprise, in fact, a broad spectrum of lesions with different phenotypes and variable biological and clinical behavior. Molecular analysis has detected specific genetic alterations in the different types of thyroid tumors. In particular, the well-differentiated carcinomas of the papillary type are characterized by activation of the receptor tyrosine kinases (RTKs), RET and NTRK1 proto-oncogenes. Cytogenetic analysis of these tumors has contributed to defining the chromosomal mechanisms leading to RTK oncogenic activation. In the majority of cases, intrachromosomal inversions of chromosome 10 and chromosome 1 led to the formation of RET-derived and NTRK1-derived oncogenes, respectively. Interestingly, molecular analysis of these oncogenes revealed their nature of chimeric fusion proteins all sharing the tyrosine kinase (TK) domains of the respective proto-oncogenes. Moreover, the sequencing of the oncogenic rearrangements led to the identification of a breakpoint cluster region in both RTK proto-oncogenes. Exposure to ionizing radiation is associated with papillary carcinomas and RET activation has been suggested to be related to this event. Conversely, RAS point mutations are frequently observed in tumors with follicular histology and have been associated with metastatic dissemination. Iodide-deficient areas seem to provide a higher frequency of RAS positive follicular carcinomas. Finally, a high prevalence of TPS3 point mutations has been detected only in undifferentiated or anaplastic carcinomas and found to correlate inversely with 8CL2 expression. All of these findings are contributing to the definition of genetic and environmental factors relevant for the pathogenesis of thyroid tumors. Moreover, the characterization of specific genetic lesions could provide significant molecular tools for a better differential diagnosis and for the development of novel therapeutic avenues for thyroid cancer.

The immunology of thyroid cancer

This article reviews the immunologic aspects of thyroid cancer, including thyroid-specific effector elements on thyroid cancer, and discusses the potential antigens, unique molecular markers, and transcription factors that could serve as targets for immunotherapy. The potential role of this type of treatment for thyroid cancer is examined also.

Thyroid cancer and thyroiditis in the goitrous region of Salta, Argentina, before and after iodine prophylaxis

OBJECTIVE

The importance of iodine intake and thyroiditis in the pathogenesis of thyroid cancer remains controversial. We have investigated the natural history of thyroid cancer and thyroiditis in a goitrous region before and after iodine prophylaxis over a 31-year period.

DESIGN

For the analysis of thyroid cancer the material was divided in two periods. The first 15 years (59 cases), including 5 years before prophylaxis, was compared with the second 16 years (85 cases), a period well after iodine supplementation of salt. Histological diagnosis of the tumours was based on the WHO system. Moderate to severe thyroiditis in the non-tumoral surrounding thyroid from female patients was recorded. For this, the material was analysed in the two periods in relation to the introduction of iodine prophylaxis in 1963, taking account of the age of the patients.

RESULTS

Papillary carcinomas formed the largest group of tumours in both periods, with nearly twice as many in the second period as the first, while the numbers of follicular and medullary carcinomas remained about the same. The ratio of papillary to follicular carcinoma rose from 1.7:1 in the first period to 3.1:1 in the second. All three thyroid lymphomas were of the non-Hodgkin's type, and all occurred in the second period in females aged over 50. A severe lymphoid thyroiditis was present in the two cases with assessable background thyroid tissue. The frequency of lymphoid infiltrate in females rose from 8% (1/12) before 1963 to 25% (18/72) after prophylaxis in the whole series. After salt prophylaxis, thyroiditis was more frequent in patients with papillary carcinoma in general (31%), and clinically significant papillary carcinomas in particular (35%), than in those with non-papillary tumours (6%) (chi 2, P < 0.05 and P < 0.025, respectively).

CONCLUSIONS

Our observations indicate that a high dietary intake of iodine may be associated with a high frequency of papillary carcinoma and thyroiditis, and that thyroiditis is more commonly associated with papillary carcinoma than with other thyroid tumours. The occurrence of non-Hodgkin's lymphomas only in the post-prophylaxis period may be linked to an increase in thyroiditis.

Thyroid cancer incidence in Asian migrants to the United States and their descendants

We compared incidence rates of primary cancer of the thyroid among United States-born and foreign-born Chinese, Japanese, and Filipino residents of the US with rates among US-born Whites. Thyroid cancers diagnosed between 1973 and 1986 occurring among individuals 15 to 84 years of age residing in western Washington state, the San Francisco-Oakland (California) area, or the state of Hawaii were included in the analysis. Population estimates by age, gender, ethnicity, and country of birth were obtained for these areas from the US Bureau of the Census. Filipino women born in the Philippines had 3.2 (95 percent confidence interval = 2.7-3.8) times the rate of thyroid cancer of US-born White women, while US-born Filipino women were not at any increased risk. Philippine-born Filipino men also had a relatively high rate of thyroid cancer (relative risk [RR] = 2.6), more so than US-born Filipino men (RR = 1.5). Among Japanese, risk of thyroid cancer varied by birthplace, but the direction of the association differed by gender and by histologic type of cancer. No clear association with birthplace was noted among Chinese men or women. These data suggest that persons residing in one or more regions from which Filipino-Americans migrated have been exposed to environmental influences that have increased their subsequent risk of thyroid cancer.

Towards understanding the molecular basis of thyroid cancer

Cancer is a multistep phenomenon and multiple genetic lesions are involved in the emergence of the cancerous lesion. This has best been demonstrated in colonic cancer. The authors review their work and that of others highlighting what is known about thyroid cancer. They implicate ras mutations predominantly in follicular carcinoma, rearrangement of the ret proto-oncogene in papillary carcinoma and the tumor suppressor genes p53 and retinoblastoma gene product in all stages of thyroid carcinoma. They find a low rate of ret proto-oncogene rearrangement in the Saudi population (>5%) as compared to elsewhere in the world (20%). They find TSH receptor message abundance to be predictive of prognosis in thyroid cancer patients. Lastly, they examine whether the abundance of the anti-metastatic gene nm23 message abundance negatively correlated with the tendency of thyroid tumors to metastasize and find that not to be the case in thyroid carcinoma. The study of oncogenes and tumor suppressor genes in the pathogenesis of thyroid cancer is in its infancy; however, rapid progress is being made in identifying genes participating in malignant thyroid cell transformation.

Gene p53 mutations are restricted to poorly differentiated and undifferentiated carcinomas of the thyroid gland

The p53 gene was analyzed in tumor specimens obtained from 52 patients with various types of carcinoma of the thyroid gland by a combined molecular and immunocytochemical approach. The histologic types included 37 well-differentiated papillary and follicular carcinomas, 8 poorly differentiated, and 7 undifferentiated carcinomas. The p53 gene was shown to be unaffected in all differentiated tumors by single-strand conformation polymorphism analysis. However, in two out of eight (25%) of poorly differentiated carcinomas and five out of seven (71%) undifferentiated carcinomas, p53 mutations were identified and subsequently characterized by DNA sequencing. One undifferentiated carcinoma displayed two areas with varying degrees of differentiation. The comparative analysis of the p53 gene, in both the more and the less differentiated area of this tumor, clearly showed that the p53 mutation was confined to the latter component of the tumor specimen. These results indicate that mutations of the p53 gene are associated with the most aggressive histologic types of thyroid tumors, such as the undifferentiated carcinoma and, to a certain extent, the poorly differentiated carcinoma, and that the alterations of this gene represent a late genetic event in human thyroid carcinogenesis.

Incidence pattern of thyroid cancer in Norway: influence of birth cohort and time period

The incidence of thyroid cancer in Norway increased about 2-fold for both sexes during the period 1955 to 1989 (4691 cases). In the last 5-year period, however, a decline was observed, especially among females. The ratio between age-adjusted incidence rates in Northern Norway compared with Southern Norway was 1.6 for females and 1.5 for males, and the incidence pattern during the period was similar in the 2 regions. The analysis of age-cohort-period models showed a strong cohort effect in both sexes. The reason for this is not clear, although radiation treatment during childhood and dietary habits may possibly be involved. A weaker but statistically significant and transient period effect was also present, giving relatively higher incidence rates, especially in the 1970s. Although this result may be consistent with an influence of radioactive fallout in the northern area, more detailed studies are needed.

The impact of geographical, clinical, dietary and radiation-induced features in epidemiology of thyroid cancer

Cancer of the thyroid accounts for less than 1% of all cancers recognised each year, but the incidence is rising. Much of the early work of the epidemiology and aetiology of thyroid cancer was based on the assumption that thyroid cancer can be treated as an entity. The recognition that two distinct types of endocrine cell occur within the thyroid has made it clear that any discussion of the aetiology and epidemiology of thyroid malignancies must take into account the histological classification of these tumours. Moreover, there are difficult problems to be considered when comparing thyroid cancer incidence across tumour registries, because of a lack of standardisation or morbidity data collection, difficulties in histological diagnosis, varying rates of diagnosis of occult papillary carcinoma, and prevalence and techniques of autopsies. So far only a relatively small proportion of thyroid cancer cases can be explained with adequate certainty as regards epidemiology and aetiology. As in cancer in general, the aetiology and epidemiology of thyroid cancer in detail remains unknown in the majority of cases.

In vitro and in vivo characterizations of established human follicular carcinoma cell line derived from thyroid cancer: a novel model for well-differentiated thyroid malignant tumor

A continuous cell line, named SMC R86 F1, was established from a surgically resected primary thyroid lesion. The cell grew as an adhering monolayer with a doubling time of about 25 hours in modified Eagle's medium supplemented with fetal bovine serum. When the cells were transplanted into athymic nude mice, tumors developed at the site of inoculation. The cells not only showed epithelial origin upon light and electron microscopic examination but also possessed a biosynthetic marker human thyroglobulin (hTg). In order to examine the iodide trapping ability of the xenografts, radioiodine at doses of 3.7 MBq was injected into the peritoneum of 131I treated nude mice bearing xenografts at about 4 weeks after the cell inoculation. Judging from the results of scintigraphic, autoradiographic and biodistribution studies, viable tissue of the xenografts in the treated mice had the ability to trap radioiodine. Histological sections of the xenografts resected from the treated mice consisted of follicle-like and trabecular growing structures, and immunohistochemically the cytoplasm of the tissues was hTg positive. The cells possessed the ability to trap radioactive iodine in vitro under the control of TSH. In addition, the expression of iodinated 19S Tg in the cell cytoplasms in the monolayer cultures was revealed by immunoblotting and autoradiographic assays. These observations provide strong evidence that the SMC R86 F1 cell line possesses well-differentiated properties of the malignant thyroid follicular epithelial cells.

Cytogenetic study of a papillary thyroid carcinoma with a rearranged chromosome 10

Cytogenetic findings of a multifocal papillary thyroid cancer and a metastatic lymph node from a 29-year-old white female patient are reported. Two clonal aberrations were observed: a trisomy 7 in one nodule, and a rearranged chromosome 10 in a separate nodule and in a lymph node. The rearrangement of 10q described here is similar to other published cases and is relevant for interpreting the molecular findings associated with thyroid cancer.

Cytogenetic and molecular genetic studies of follicular and papillary thyroid cancers

Cytogenetic studies have shown frequent clonal abnormalities in papillary carcinoma (PTC) and follicular carcinoma (FTC). Loss of heterozygosity (LOH) may suggest the presence of tumor suppressor genes and has not been reported in these neoplasms. These studies were undertaken to determine if consistent chromosomal abnormalities are associated with thyroid cancer, to determine likely regions for molecular genetic investigations, and to determine if there is allelic loss in thyroid tumors. Cytogenetic analysis of 26 PTC and 5 FTC showed clonal abnormalities in 9 and included -Y, +5, or inv(10)(q11.2q21.2) in PTC, and -Y or near haploidy in FTC. Using DNA probes specific for chromosomes 1, 3, 10, 16, and 17, we carried out restriction fragment length polymorphism analysis on 6 FTC, 3 follicular adenomas (FA), and 12 PTC. LOH of all informative loci on chromosome 3p was observed in all 6 FTC, but not in FA or PTC. No LOH was observed for loci mapped to chromosome 10 in PTC. Our results suggest: cytogenetic abnormalities of chromosome 10q are associated with PTC; cytogenetic and molecular abnormalities of chromosome 3 are associated with FTC; and a tumor suppressor gene may be present on the short arm of chromosome 3 important for the development or progression of FTC.

Loss of heterozygosity on chromosome 1p in thyroid adenoma and medullary carcinoma, but not in papillary carcinoma

We analyzed 53 loci on 21 chromosomes other than chromosome 4 to detect possible loss of heterozygosity in 31 thyroid tumors using polymorphic DNA markers that detect allelic deletions at specific chromosomal loci. Loss of heterozygosity on chromosomes 1, 7 and 12 was detected in one follicular thyroid adenoma, and on chromosome 1 in two medullary thyroid carcinomas. However, no loss of heterozygosity was detected at any of the loci examined in papillary thyroid carcinomas. These results suggest that chromosomal loss detected in thyroid adenoma is one of the signals for risk of premalignant transformation, and that inactivation of unknown genes on chromosome 1p contributes to tumorigenesis of medullary thyroid carcinoma. Some genetic changes other than chromosomal losses may participate in the tumorigenesis of papillary thyroid carcinoma.

Diet and thyroid cancer: a pooled analysis of four European case-control studies

The relationship between frequencies of consumption of selected indicator foods and the risk of thyroid cancer was investigated in a pooled analysis of 4 case-control studies conducted in 3 areas of northern Italy and the Swiss Canton of Vaud, on a total of 385 histologically confirmed cases of thyroid cancer and 798 controls in hospital for acute, non-neoplastic, non-hormone-related diseases. Cases tended to consume significantly more frequently a number of starchy foods: the odds ratio (OR) for the highest vs. lowest tertile was 1.8 for pasta or rice, 2.1 for bread, 1.6 for pastry and 2.0 for potatoes. ORs also tended to be above unity for several types of meat and significantly so for chicken and poultry, cooked ham, salami and sausages. Raw ham and fish were significantly protective (OR = 0.7 in the highest tertile for both). Significant direct associations were observed with cheese (OR = 1.4 for the highest tertile), butter (OR = 2.1) and oils other than olive (OR = 1.6). The risk estimates were below unity for most types of vegetables and fruits, and the inverse trends were significantly for carrots (OR = 0.6 for the highest tertile), green salad (OR = 0.6) and citrus fruits (OR = 0.7). No association was observed with alcohol intake. These results were consistent and reproducible across various study centers.

Hyperfunctioning metastatic follicular thyroid carcinoma in Pendred's syndrome

A 66-year-old woman with Pendred's syndrome underwent a partial thyroidectomy when she was 17 years old. At the age of 52 years, she had a second thyroid operation because of hyperthyroidism due to a toxic multinodular goiter with a mediastinal extension consisting of several separate nodules. Five years later a hyperfunctioning metastatic follicular carcinoma was diagnosed histologically. After treatment with radioactive iodine, the patient was well. To the authors' knowledge, this is the first description of a metastatic follicular thyroid carcinoma in Pendred's syndrome and the first report of hyperthyroidism occurring after malignant degeneration of a dyshormonogenetic goiter.

Descriptive epidemiology of thyroid cancer in the Swiss Canton of Vaud

Although substantial decreases have been recorded, age-standardized mortality rates from thyroid cancer in Switzerland are still the highest in Europe in men (0.9/100,000), together with those from Austria, and the third highest (1.0/100,000) in women. Detailed analysis of 308 new cases registered between 1974 and 1987 in the Swiss Canton of Vaud revealed an overall incidence rate of 1.36/100,000 men (world standard) in 1974-1980 and of 1.74/100,000 in 1981-1987. Corresponding values for women were 4.28 and 4.51, respectively. Thus, women constituted the majority of all cases (76%). Papillary carcinoma was the most frequent histological type (53%) followed by follicular (27%), undifferentiated (5%) and medullary (2%); other morphologies and clinical tumours accounted for 13% of the whole series. In both sexes, most of the apparent increase over the calendar period was restricted to the papillary type. Overall 5- and 10-year survival rates were 71% and 57%. When various factors were introduced in a Cox proportional-hazard model, young age at diagnosis (hazard rate for greater than or equal to 65 years vs less than 45 = 14.7; 95% confidence interval = 7.5-29.1) and good histological differentiation (hazard rate for papillary and follicular vs undifferentiated = 0.4) emerged as strong favourable and independent prognostic factors. The reduced hazard rate for women, other factors being equal, was of borderline significance (0.7, 95% confidence interval = 0.5-1.0), whereas no significant difference was observed between follicular and papillary carcinomas, and calendar periods of diagnosis.

Tumours in Iceland. 11. Malignant tumours of the thyroid gland. A histological classification and epidemiological considerations

All malignant primary tumours of the thyroid gland submitted for histological diagnosis in Iceland during the 30 years 1955-1984, and available for review, were typed histologically according to the World Health Organization classification but also taking into account the more recent well recognized follicular variant of papillary carcinoma. A total of 480 thyroid tumours were classified with a female--to male ratio of 2.8 (367 females, 129 males). The age distribution is much what would be expected, the anaplastic type of carcinomas occurring in the elderly while papillary and follicular tumours occur over a much wider age range. The incidence of thyroid carcinomas in Iceland is about 2-3 times higher than in the other Nordic countries. This is largely due to an unusually high incidence of the papillary type of carcinoma. Overall, the papillary carcinoma accounted for 80% of thyroid malignancies. The tumours diagnosed incidentally at autopsy were about 20% of the entire material, and these tumours were only of the differentiated types of thyroid carcinoma. Even if the incidentally diagnosed tumours are excluded, the percentage of papillary tumours is 77% which is unusually high. The papillary type of carcinomas occasionally occurred in familial clusters in Iceland but not sufficiently to account for the unusually high incidence. Some of the possible etiological factors are discussed.

Descriptive epidemiology of thyroid cancer in Hawaii

Data were analyzed from 1110 thyroid cancer cases between 1960 and 1984 identified by the Hawaii Tumor Registry, a population-based Statistics, Epidemiology and End Results (SEER) participant covering the entire state of Hawaii. Incidence rates for men and women were relatively stable during this 25-year period. The overall age-adjusted rates were 8.1 per 100,000 for women and 3.1 per 100,000 for men. There was a significant variation in incidence on the basis of ethnicity, with the highest rates for women occurring in Filipinos (18.2 per 100,000) and for men in Chinese (6.3 per 100,000). A comparison of different populations around the world showed that Hawaii has some of the highest reported incidence rates for thyroid cancer. In addition, a comparison of ethnic-specific incidence rates for groups living in Hawaii with people of the same ethnic backgrounds living in other geographic areas showed that Hawaii residents generally have much higher rates, suggesting that environmental influences are responsible for the unusually high rates in Hawaii.

The relation of susceptibility to and biologic behavior of thyroid epithelial cell cancer to HLA-DR1

Fifty-two patients with thyroid epithelial cell cancer were studied for evidence of association with human leukocyte antigens (HLA). Twenty-eight patients (53.8%) and 19.4% of 160 controls were HLA-DR1-positive, conferring a relative risk of 4.85 (chi 2 = 21.3, P less than 0.0001). HLA-DR1 was increased in all histologic types of thyroid cancer. Interestingly 10 of 12 patients with metastatic disease were DR1-positive compared to 18 of 41 patients without metastases (relative risk = 6.1, chi 2 = 4.7, P less than 0.05). This study suggests that major histocompatibility complex-linked gene(s) determine susceptibility to and the biologic behavior of thyroid cancer.

Thyroid cancer. Survival in 148 cases followed for 10 years or more

One hundred forty-eight patients with differentiated carcinoma of the thyroid treated between May 1954 and April 1973 are presented. There were 89 papillary and 59 follicular carcinomas. They were classified according to Woolner criteria. Treatment consisted of surgery I-131 and thyroid hormone. Recurrences occurred in 8.7% of the patients, and lethality at the end of the observation period was 3.3%. The impact of histologic type, extent of the primary, and age of the patient at the time of treatment on prognosis were studied. The data were submitted to statistical analysis. This study revealed that these factors are determinant on prognosis. Best survival rates were observed in patients 40 years of age or younger at the time of treatment, in patients with intrathyroid papillary carcinomas, and in patients with noninvasive follicular carcinomas.

High relative frequency of thyroid papillary carcinoma in northern Portugal

Two hundred and twelve papillary and 40 follicular carcinomas were found in 3002 thyroid glands examined from 1931 to 1975 in four Laboratories of Pathology that fairly cover northern Portugal. There was a striking preponderance of women both in papillary (female:male = 6.9:1) and follicular carcinoma (5.7:1). Sex-specific frequency of malignancy was significantly greater in men (13.3%) than in women (8.8%). The overall papillary/follicular ratio was 5.3:1 and did not significantly change throughout the study period. Papillary/follicular ratio was not significantly greater in litoral (5.5:1) than in regions with a low iodine intake and a relatively high prevalence of goiter (3.5:1). It is advanced that this high relative frequency of papillary carcinoma in northern Portugal, even in goiter areas, may reflect the existence of a racial factor since there is not enough evidence to support the influence of dietary iodine, previous irradiation and concurrent thyroiditis.