Advances in the diagnosis and management of thyroid neoplasms

[Anaplastic thyroid carcinoma]

Well-differentiated thyroid carcinoma (TC), as papillary and follicular carcinoma, usually follows a relatively benign course after total thyroidectomy and thyroid remnant ablation with 131I. In contrast, anaplastic TC or undifferentiated TC, also derived from the thyroid follicular epithelium, refers to one of the more aggressive human malignancies, which have lost most or all characteristics of the tissue from which it originated. Rapid tumor growth presages early mortality unless combined therapy is aggressively pursued. Definitive curative approach does not exist for most patients. The best approach is still aggressive surgery combined with the associated use of new chemotherapies associated with local external beam radiotherapy.

Thyroid cancer review 2: management of differentiated thyroid cancers

This is the second review article on thyroid cancer dealing with the common differentiated types that comprise 90% of thyroid cancers. Despite clinical management guidelines offered by a number of organisations including the British Association of Otolaryngologists and Head and Neck Surgeon, The British Thyroid Association, The American Association Of Endocrinologists, The American Thyroid Association and the National Cancer Centre Network, debate regarding the management of differentiated thyroid cancer continues. This is because of the absence of good quality research evidence as a consequence of the natural history of this disease.

Role of Fine-needle Aspiration Biopsy and Frozen Section in the Management of Papillary Thyroid Carcinoma Subtypes

Since fine-needle aspiration biopsy (FNAB) was introduced, the value of frozen section (FS) has been questioned. This study compares FNAB and FS sensitivities among the usual form of papillary thyroid cancer (uPTC) and variants of PTC such as tall cell (tcPTC), follicular (fPTC), and Hurthle cell (HcPTC). A total of 257 patients who underwent preoperative FNAB, intraoperative FS, and thyroidectomy for PTC were, randomly selected from a database of a university teaching hospital in Toronto. There were 218 females (84.8%) and 39 males (15.2%), from 19 to 89 years of age (mean of 44 years), having uPTC (n = 212), fPTC (n = 24), HcPTC (n = 14), and tcPTC (n = 7). Data were analyzed using chi2 test. Sensitivities were calculated by division of true positives and by the sum of true positives and false negatives. True positives had to reflect a conclusive diagnosis of cancer. The FNAB sensitivities were uPTC (39.2%), fPTC (25%), HcPTC (42.9%), tcPTC (85.7%), similar to FS sensitivities (p = 0.497) for uPTC (44.3%), fPTC (16.7%), HcPTC (42.9%), and tcPTC (71.4%). Use of FS following FNAB increased sensitivities for uPTC to 56.1%, fPTC to 29.2%, and tcPTC to 100%. In addition, FS did not increase FNAB sensitivity in HcPTC. Combination FNAB plus FS failed in 43.9% of uPTC, 70.8% of fPTC, and 57.1% of HcPTC. We concluded that FNAB and FS sensitivity vary with PTC subtype and are still necessary for selection and treatment. The recognition of morphologic subtypes of PTC from the FNAB could optimize the selection of patients for intraoperative FS, enhance the preoperative assessment of prognosis, facilitate the surgical planning, and simplify the preparation of postoperative adjuvant therapy.

The role of ultrasound-guided fine-needle aspiration biopsy in the previously treated patient with thyroid cancer

The aim of the present study was to evaluate the effectiveness of ultrasound-guided fine-needle aspiration in detecting locoregional recurrence in previously treated patients with thyroid cancer. A retrospective analysis of ultrasound-guided fine-needle aspiration (FNA) biopsy was carried out for suspected recurrence of thyroid cancer over a 5-year period at a single institution. There were 37 biopsies in 37 patients. Each patient's ultrasound report, cytology report and medical notes were examined to determine the result of the biopsy and the patient's outcome. There were 29 true-positives, 6 true-negatives, 1 false-negative and 1 inadequate biopsy. Ultrasound-guided FNA, therefore, had a sensitivity of 96.7%, specificity of 100% and overall accuracy of 97.2% in detecting recurrence. Ultrasound-guided FNA is an accurate method of identifying suspected recurrence.

Molecular genotyping of medullary thyroid carcinoma can predict tumor recurrence

Medullary thyroid carcinoma can have an aggressive behavior, and little is known about the molecular basis for clinical outcome. Defining risk of recurrent or metastatic disease is difficult, and it has been limited to clinical and pathologic features, such as advanced age, cervical lymph node metastases, and stage at presentation. Using microdissection and genotyping, we studied 11 cases of medullary carcinoma for allelic losses in a panel of known tumor suppressor genes. The tumor suppressor genes with the most frequent allelic losses were NF2, l-myc, and p53 (75%, 44%, and 44%, respectively). The average frequency of allelic loss across all tumors was 44% and was higher in tumors that recurred. A combination of previously described high-risk variables (increased patient age and cervical lymph node metastases) with the frequency of allelic loss yielded a high-risk group, in which 6 of 6 patients recurred, and a low-risk group, in which 0 of 5 patients recurred (P = 0.004). Frequency of allelic loss in tumor suppressor genes may provide a useful adjunctive prognostic test in medullary thyroid carcinoma.

Proteomic and postproteomic characterization of keratan sulfate-glycanated isoforms of thyroglobulin and transferrin uniquely elaborated by papillary thyroid carcinomas

Previous studies have suggested that surface components of papillary thyroid carcinoma (PTC) cells may be aberrantly glycanated, but the precise nature of these molecules has not been unveiled nor documented to be of clinical relevance. A monoclonal antibody was raised against a unique keratan sulfate (KS) determinant and used to differentially screen benign and malignant thyroid tissue for the expression of components carrying these moieties. In a total of 349 cases of benign and malignant thyroid lesions, 100% of the 115 PTC cases examined (including various histological subtypes) were found to contain KS-bearing molecules, whereas these were virtually absent from benign tissues and other thyroid tumors, with the exception of 21% of the follicular carcinoma cases analyzed. A composite immunoaffinity chromatography, immunochemistry, and mass spectrometric approach revealed that the PTC-specific KS-bearing macromolecules were unique glycoforms of thyroglobulin and transferrin. Combined, reciprocal immunoprecipitation and Western blotting further indicated that the former glycoform predominated and that most of the transferrin produced by PTC was glycanated with KS moieties. Fluorescent keratanase II-based fingerprinting of the KS moieties bound to these isoforms further demonstrated several PTC-specific peculiarities: 1) that a considerable portion of the moieties was covalently attached via a novel core protein linkage structure; 2) they had an unusual extended average length; 3) an unusual relative ratio of highly sulfated disaccharides terminating with alpha (2-3)-linked N-acetylneuraminic acid capping residues; and 4) a novel unidentified oligosaccharide moiety at the nonreducing terminus. Comparative analysis of the relative distribution of transferrin in benign versus PTC tissues highlighted a marked malignancy-associated abundance of the molecule, with a >75% frequency in expression in PTC. These findings demonstrate that PTC cells synthesize unique post-translationally modified thyroglobulin and transferrin variants in situ that may be directly exploitable for diagnosis, through histological and noninvasive cytological procedures; for devising novel strategies for antibody-guided imaging of this tumor in vivo; and for postsurgery follow-up of PTC patients.

Can Fine-Needle Aspiration Biopsy of Thyroid Nodule Help in Determining the Extent of Surgery in Follicular and Hurthle Cell Neoplasm at a Community Teaching Institution?

Fine-needle aspiration biopsy (FNAB) was used to evaluate cold thyroid nodules in 179 patients treated between 1990 and 1998. The purpose of this study was to see whether FNAB findings of follicular or Hurthle cells could help in planning the extent of thyroid surgery. Group I patients (47) had findings suggestive of follicular or Hurthle cell neoplasm. Group II patients (132) had inconclusive results. In group I FNAB was 100 per cent correct in diagnosing follicular or Hurthle cell neoplasm with a high percentage of malignant findings (malignancy 85 per cent and benign adenoma 15 per cent). In Group II malignancy was found in 16 per cent and benign pathology in 84 per cent. Women were more likely to have malignancy than men. The average age was over 50 years in patients with either malignant or benign nodules. In addition there was no significant difference in average size of benign or malignant nodules (2.9 vs 2.6 cm respectively). When an FNAB finding was suggestive of neoplasm malignancy was found in 85 per cent. On the other hand when an FNAB was inconclusive malignancy was present in 16 per cent. Thus we conclude that using FNAB finding can guide surgical resection and recommend performing total or subtotal thyroidectomy when FNAB is suggestive of neoplasm and lobectomy when FNAB is inconclusive.