Thyroid carcinoma: clinical, pathologic correlations

mRNA expression in papillary and anaplastic thyroid carcinoma: molecular anatomy of a killing switch

Anaplastic thyroid carcinoma (ATC) is the most lethal form of thyroid neoplasia and represents the end stage of thyroid tumor progression. No effective treatment exists so far. ATC frequently derive from papillary thyroid carcinomas (PTC), which have a good prognosis. In this study, we analyzed the mRNA expression profiles of 59 thyroid tumors (11 ATC and 48 PTC) by microarrays. ATC and PTC showed largely overlapping mRNA expression profiles with most genes regulated in all ATC being also regulated in several PTC. 43% of the probes regulated in all the PTC are similarly regulated in all ATC. Many genes modulations observed in PTC are amplified in ATC. This illustrates the fact that ATC mostly derived from PTC. A molecular signature of aggressiveness composed of 9 genes clearly separates the two tumors. Moreover, this study demonstrates gene regulations corresponding to the ATC or PTC phenotypes like inflammatory reaction, epithelial to mesenchymal transition (EMT) and invasion, high proliferation rate, dedifferentiation, calcification and fibrosis processes, high glucose metabolism and glycolysis, lactate generation and chemoresistance. The main qualitative differences between the two tumor types bear on the much stronger EMT, dedifferentiation and glycolytic phenotypes showed by the ATC.

Changes in the balance between proliferation and apoptosis during the progression of malignancy in thyroid tumours

The aim of this study was to gain better insight into molecular changes which reflect disturbances in the balance between proliferation and apoptosis during progression of thyroid malignancy from papillary microcarcinoma (PMC) via clinically manifest papillary carcinoma (PTC) to anaplastic carcinoma (ATC). The apoptosis related molecules (Bcl-2, Bax) and proliferation related marker (PCNA) were analysed immunohistochemically in 120 archival cases comprising PMC (n=34), PTC (n=52) and ATC (n=34). In addition, in situ apoptotic cell death was analysed by the TUNEL method. The average Bcl-2 staining score did not differ between PMC and PTC (p>0.05), but was significantly lower in ATC (p<0.05).The Bax score was higher in PTCs and ATCs than in PMCs (p<0.05). Due to these changes, the Bcl-2/Bax ratio showed a marked decrease from PMC to ATC (p<0.05), while proliferation activity increased significantly from PTC to ATC (p<0.05). Despite high Bax expression, the rate of apoptotic cell death was low in the investigated carcinomas, especially in ATC, i.e. the increase in proliferative activity was not counterbalanced with appropriate cell death. Differences were found in the expression of apoptotic molecules (Bcl-2 and Bax), their ratio (Bcl-2 /Bax) and in the rate of apoptotic cell death and proliferative activity between PMC, PTC and ATC, indicating that disturbances in the balance between apoptosis and proliferation, in favour of the latter, occur gradually during the progression of malignancy in thyroid tumours.

Apoptosis and proliferation related molecules (Bcl-2, Bax, p53, PCNA) in papillary microcarcinoma versus papillary carcinoma of the thyroid

AIM

To gain a better insight into the differences in biological behaviour between papillary microcarcinoma (PMC) and clinically evident papillary thyroid carcinoma (PTC).

METHODS

Immunohistochemical analysis of apoptosis related molecules (Bcl-2, Bax, p53) and proliferation related marker (PCNA) in 39 archival cases of PMC and 46 cases of PTC.

RESULTS

Bcl-2 and Bax were expressed in most PMCs and PTCs. The average Bcl-2 staining score did not differ significantly between PMCs and PTCs (p > 0.05), but the average Bax score was significantly lower in PMCs (p < 0.05). The Bcl-2/Bax ratio was significantly higher in PMCs than in PTCs (p < 0.05). The expression of p53 was similar in PMCs and PTCs, without a correlation with clinical data, but was associated with high Bax expression (p < 0.05) in these cases in both groups. Non-malignant tissue expressed only Bcl-2, but not p53 or Bax. PCNA expression was significantly lower (p < 0.05) in PMC than in PTC and positively correlated with tumour size (p < 0.05).

CONCLUSIONS

The higher Bcl-2/Bax ratio and lower proliferative activity in PMC suggest differences from PTC in the balance between apoptosis and proliferation. However, the presence of p53 and Bax in PMC indicates malignant potential, and thus PMC should be treated with caution.

Galectin-3 expression in papillary thyroid carcinoma: relation to histomorphologic growth pattern, lymph node metastasis, extrathyroid invasion, and tumor size

BACKGROUND

Galectin-3 has been recently recognized as a promising presurgical marker of thyroid malignancy.

METHODS

Galectin-3 expression was examined immunohistochemically in 202 specimens of papillary thyroid carcinoma (PTC) in relation to histomorphologic subtypes and clinicopathologic data. RESULTS.: The sensitivity of galectin-3 immunostaining versus conventional histology was 98% (100 of 102) for classical PTC, 85.2% (46 of 54) for follicular variant, and 50% (23 of 46) for follicular/solid variant of PTC. All cases (n = 36) involving lymph node metastases and 42 of 45 cases with extrathyroid invasion expressed galectin-3. However, among the galectin-3-positive cases (n = 169), 133 were without lymph node metastases, and 127 were without extrathyroid invasion. Galectin-3 expression was not related to the size of intrathyroid PTC.

CONCLUSIONS

Galectin-3 immunohistochemical expression itself is not an indicator of local metastatic spread or extrathyroid invasion of PTC, thus being irrelevant clinically from this aspect. Galectin-3 is an excellent marker for classical PTC but must be used with caution in diagnosing unconventional variants of PTC because of the possibility of false-negative results.

A model for predicting outcomes in patients with differentiated thyroid cancer and model performance in comparison with other classification systems

BACKGROUND

This study was performed to determine the prognostic factors for differentiated thyroid cancer, and to establish a mathematical prognostic model.

STUDY DESIGN

A retrospective study was conducted in 347 differentiated thyroid cancer patients. Univariate and multivariate prognostic factor analyses were carried out using the Kaplan-Meier and Cox regression methods.

RESULTS

Without adjustment for treatment in the multivariate analysis, age, tumor size, angioinvasion, and distant metastasis were significant predictors of outcomes. The very low-risk, low-risk, high-risk, and very high-risk groups were identified from the logistic regression equation. Overall and event-free survival estimations at 10 years were 100% and 100% for very low-risk patients, 88% and 75% for low-risk patients, 30% and 16% for high-risk patients, and 5% and 0% for very high-risk patients. Inclusion of treatment in the multivariate analysis showed, in addition to other variables, that both total or near total thyroidectomy (versus thyroidectomy less than total and near total thyroidectomy, p = 0.0002; hazard ratio, 0.4; 95% CI, 0.3-0.7) and adjuvant radioactive iodine treatment (versus no treatment with radioactive iodine, p = 0.0001; hazard ratio, 0.5; 95% CI, 0.2-0.8) were associated with a reduced hazard of death in the followup period. By subgroup analysis, total and near total thyroidectomy, along with radioactive iodine, appeared to provide a survival benefit for all patients except those in the very low-risk group.

CONCLUSIONS

The proposed mathematical model is satisfactory for predicting outcomes. Total and near total thyroidectomy along with radioactive iodine treatment might provide a survival advantage for differentiated thyroid cancer, except for those with very low risk.

Differential expression of galectin-3 in papillary projections of malignant and non-malignant hyperplastic thyroid lesions

Galectin-3 is a a beta-galactoside binding protein recently proposed to be a promising presurgical molecular marker for distinguishing benign from malignant thyroid neoplasms. We analyzed galectin-3 expression immunohistochemically in papillary areas of hyperplastic lesions of benign thyroid tissue in comparison with malignant papillary projections of papillary thyroid carcinoma (PTC). A monoclonal antibody to galectin-3 and ABC immunohistochemical technique were used to evaluate galectin-3 expression in 26 cases of benign papillary hyperplasia (8 cases of hyperplastic adenoma, 8 cases of hyperplastic colloid goiter, 10 cases of Graves disease) in comparison with 25 cases of PTC. Immunohistochemical results showed no reactivity for galectin-3 in papillary areas of benign hyperplastic lesions. Strong cytoplasmic galectin-3 immunoreactivity was found in all 25 cases of PTC. These results show that galectin-3 expression is a feature of malignant papillary projections but not of benign papillary hyperplasia. Thus, the immunohistochemical evaluation of galectin-3 might contribute to differential diagnosis between malignant and benign thyroid lesions with papillary projections.

[Pathohistologic and immunohistochemical characteristics of thyroid carcinoma]

Numerous pathohistologic criteria, difficulties and pitfalls in the process of diagnosing of thyroid carcinoma are discussed. Benign hyperplastic papillae may be present in colloidal cystic goiter and hyperplastic goiter. These structures are lined by cells with normochromatic nuclei and do not disturb the thyroid tissue architecture. Papillae in papillary thyroid carcinoma have cells with ground-glass, hypochromatic nuclei. Follicles inspissated in capsula of follicular or even colloidal adenoma may be evaluated as capsular invasion--diagnostic feature of follicular carcinoma. Undifferentiated thyroid carcinoma is sometimes similar to fibrosarcoma and reveal cellular pleomorphism, anaplasia and numerous foci of necrosis. Medullary thyroid carcinoma with scanty stromal amyloid, its papillary variant and carcinoid-like histologic type consist of oval cells with eosinophilic cytoplasm and dark nuclei.

The accuracy of fine-needle aspiration biopsy and frozen section in patients with thyroid cancer

A total of 1076 patients with thyroid nodules were reviewed. The accuracy of fine needle aspiration biopsy (FNAB) and frozen section (FS) were compared and clinical risk factors were analyzed. Our results indicate that 67.9% are benign and 32.1% are malignant with the predominance of papillary thyroid cancer (75.1%). Overall diagnostic accuracy for FNAB and FS were 90.8%-91.2% and 89.1%-90.5%, respectively. There were no significant differences between the diagnostic accuracy on FNAB and FS in all tumors except the follicular adenoma and carcinoma. The diagnostic accuracy of FS was higher than FNAB in patients with follicular adenoma (89.3% vs. 58.9%, p < 0.001) and but lower than FNAB in patients with follicular carcinoma (46.2% vs. 92.3%, p < 0.001). In conclusion, FNAB is cost effective in the preoperative evaluation of thyroid nodule. FS could be eliminated in most cases except with follicular and Hürthle cell neoplasms. FS is valuable when result of FNAB is suspicious or unavailable. FS is more appropriate in deciding the extent of thyroidectomy in follicular neoplasm and FNAB is more reliable initial approach to surgery in patients with Hürthle cell neoplasm. Clinical risk factors may help in selecting patients for surgery but cannot exceed FS in deciding the extent of thyroidectomy in patients with follicular and Hürthle cell neoplasms.

Hepatocyte growth factor/scatter factor-induced intracellular signalling

Hepatocyte growth factor (HGF) identical to scatter factor (SF) is a glycoprotein involved in the development of a number of cellular phenotypes, including proliferation, mitogenesis, formation of branching tubules and, in the case of tumour cells, invasion and metastasis. This fascinating cytokine transduces its activities via its receptor encoded by the c-met oncogene, coupled to a number of transducers integrating the HGF/SF signal to the cytosol and the nucleus. The downstream transducers coupled to HGF/MET, most of which participate in overlapping pathways, determine the development of the cell's phenotype, which in most cell types is dual.

The relative roles of endemic goiter and socioeconomic development status in the prognosis of thyroid carcinoma

BACKGROUND

It generally is accepted that the prognosis of thyroid carcinoma is more severe in areas in which goiter is endemic. It could be assumed that this prognosis also is less favorable in developing countries.

METHODS

Clinical features and tumor histology of 1000 consecutive patients were studied: Patient data from the endemic area (EA) were compared with those from the nonendemic area (NEA). In addition, patients from the years 1966-1981 (P1) were compared with those from 1982-1991 (P2). It is obvious that the country's socioeconomic status and health care system improved between the two periods.

RESULTS

The anaplastic and follicular types of thyroid carcinoma were more frequent in EAs (14% and 42.13%, respectively) than in NEAs (6.25% and 38.40%, respectively). The frequency of the anaplastic carcinoma during P1 (16.03%) decreased by half during P2 (7.79%), whereas the frequency of follicular carcinoma remained stable (35.85% and 40.46%, respectively). Clinically, more advanced stages (tumor size, local and distant disseminations) were observed in the study country than in developed countries. A clearcut improvement was observed during P2 whereas differences between the EA and NEAs were few. Survival rates (follicular and papillary types only) were not found to be different between EAs and NEAs (5-year survival: 81.44% and 75.32%, respectively; 10-year survival: 67.93% and 69.52%, respectively). A significant (P < 0.01) increase was observed between P1 and P2 (5-year survival: 72.69% and 84.80%, respectively; 10-year survival: 58.77% and 83%, respectively).

CONCLUSIONS

Compared with endemic goiter, low socioeconomic status appeared to be the major factor accountable for the high prevalence of advanced stage cases and anaplastic carcinomas. Iodine deficiency appeared to play a specific role in the increased prevalence of follicular types of thyroid carcinoma.

Therapeutic strategies and long-term results in differentiated thyroid cancer

Differentiated thyroid carcinoma (DTC) is usually an indolent tumor associated with a low mortality. However, DTC, particularly papillary thyroid carcinoma, happens to be a multicentric tumor and tends to spread to the regional lymph nodes in the early stage of the disease; some patients with DTC do die from metastatic or recurrent disease. Despite the small number of these patients, therapeutic strategies designed to prevent such outcomes should be pursued. In this review, we attempt to evaluate the impact of different therapeutic strategies on survival and recurrence. Consequently, we conclude that the surgical approach to DIC should be individualized on the basis of the biologic behavior of the tumor, rather than on the extent of cancer involvement in the thyroid and regional lymph nodes. It is mandatory to expand our efforts to identify high-risk patients more accurately, thereby facilitating more rational approaches to treatment.

Late bone metastasis from an encapsulated follicular carcinoma of the thyroid without capsular and vascular invasion

A unique case of encapsulated follicular carcinoma of the thyroid, which lacked histologic evidence of capsular and vascular invasion but developed a late bone metastasis, is described. The thyroid tumor was found in a 42-year-old man. It was relatively small (2.5 cm) and totally encapsulated. Histologically, the thyroid tumor showed a microfollicular growth pattern of follicular cells and revealed no histologic evidence of nuclear atypia, mitotic figures or capsular and vascular invasion. The diagnosis of microfollicular adenoma was made and partial thyroidectomy was performed. Bone (rlb) metastasis of the thyroid tumor developed 22 years after the thyroidectomy. The present case suggested that capsular and/or vascular invasion is not always sufficient for the diagnosis of encapsulated follicular carcinoma of the thyroid.

Medullary thyroid carcinoma experienced at Kanazawa University Hospital

Eleven cases of medullary thyroid carcinoma (MTC), which were experienced at Kanazawa University Hospital between 1975 and 1993, were examined to correlate the clinical, histologic, and immunohistochemical findings. Seven patients were women and four men, and the mean age was 46.6 years. The mean follow-up was 88.3 months. Three patients had familial non-multiple endocrine neoplasia (MEN) MTC (familial MTC unassociated with other endocrinopathies) and the remaining eight had sporadic disease. At the end of the observation period, six patients were alive without disease and four were alive with metastatic disease. One patient died of MTC 8.3 years after surgery. Thus, the 10-year survival and disease-free survival rates were 67% and 53%, respectively. Histologically MTCs from the 10 surviving patients showed a classic type, while the one patient who died had a tubular variant MTC. Immunohistochemically, there were no significant correlations between the outcome of the patients and the expression of calcitonin (CT), carcinoembryonic antigen (CEA), calcitonin gene-related peptide (CGRP), or chromogranin A (CgA) in the primary tumors, and there were no differences in expression of these antigens between the primary and the recurrent tumors. Although only a small number of patients with MTC were studied here, it was suggested that the prognosis of MTC is worse than that of papillary and follicular thyroid carcinoma. The patients with lymph node involvement at the time of primary surgery showed a high risk of persistent or recurrent disease. The expressional level for the antigens did not influence the prognosis of MTC.

Thyroid Carcinoma in Japan and the West: Similarities and Differences

Geographic or ethnic differences in the incidence of thyroid carcinoma, as well as in the histologic distribution of thyroid carcinoma between Japan and Western countries, have been described but are still unclear. The recent establishment of histologic criteria for the diagnosis of thyroid carcinoma by the WHO committee has facilitated the comparison of clinicopathological data of patients with thyroid carcinoma all over the world. The aim of the present review article is to clarify the epidemiological and clinicopathological differences of thyroid carcinoma between Japan and Western countries. We found recently no significant differences in the incidence, mortality, and histologic distribution of thyroid carcinoma between Japan and Western countries; this was contrary to our expectation. This is likely attributable to westernization of the Japanese diet, standardized medical levels, and international standardization of histologic criteria of thyroid carcinoma.

Poorly differentiated ('insular') carcinoma of the thyroid

Three cases of unusual poorly differentiated ('insular') carcinoma of the thyroid gland are presented. These three thyroid carcinomas were large; the tumors from patients 1 and 3 were encapsulated, and that from patient 2 showed invasive growth. Microscopically the tumors were characterized by well-defined solid nests (insulae), which were composed of rather small and uniform tumor cells with round to oval nuclei. Formation of small and colloid-containing follicles was associated with these nests to varying degrees. The tumors of patients 1 and 3 were composed entirely of insular components, but that of patient 2 was associated with small areas of well-differentiated follicular carcinoma. The metastatic tumors of patients 1 and 2 were essentially similar to the primary with small foci of follicular carcinoma. Patient 1 is alive with local and mediastinal node recurrences, but patient 2 died of the disease with local recurrences and metastases to lungs, bones and skin. Patient 3 had no recurrences and died of unrelated disease 5 years after surgery. The present study indicates that insular carcinomas have characteristic histologic features and a less favorable prognosis, confirming the findings of previous studies.