Thyroid carcinoma
	Worst prognosis is observed in advanced forms of thyroid differentiated carcinoma. The experience of Gonzalez-Prado and collaborators (Santiago de Chile) have indicated that 37 patients (out of a cohort of 359 cases of thyroid cancer) had invasion of the larynx, invasion of pre-tracheal muscles or extensive lymph node metastases. In spite of total (25) or near total (12) thyroidectomies followed by lymph nodes resection and ablative doses of radioiodine, 34 (91.9%) patients died of the disease. The authors commented that this worst prognosis was also linked to the relatively advanced age of the patients. Follow-up serum thyroglobulin levels is linked to serum TSH concentrations in patients submitted to total thyroidectomy for differentiated thyroid cancer, reported Guillen et al. (Buenos Aires, Argentina). In a cohort of 152 patients (131 with papillar, 21 with follicular cancer) serum TSH was measured by a third generation assay (normal range: 0.6-3.3 mU/L) and serum Tg by IRMA (1.9-38 ng/mL). The value for serum Tg cut-off was established at 8.5 ng/mL and 115 patients were below this value when TSH was less than 1.5 mU/L. A relatively higher proportion of serum Tg above 8.5 ng/mL was observed when TSH was higher than 1.5 mU/L. They concluded that an effective suppression of serum TSH below 1.5 mU/L should be maintained during the follow-up of all patients operated for thyroid cancer. Focal Radioiodine concentration at the basis of the mouth was reported by Gutierrez et al. (San Isidro, Argentina). In a group of patients (n = 18) with a negative whole body scan but with elevated serum Tg levels, persistent radioiodine concentration at the basis of the mouth was detected either after a tracer dose of 10 mCi or 7 days after the therapeutic doses (70-200 mCi). The abnormal localization of radioiodine was bilateral in 13 patients and unilateral in 5 patients. This abnormal tissue (probably ectopic thyroid tissue) was relatively resistant to treatment with therapeutic doses of radioiodine and could be constituted of fetal-like thyroid tissue not removed at operation. The prognostic value of serum Tg during suppressive doses of L-T4 was evaluated by Chebel and co-authors (Buenos Aires, Argentina) in 46 patients (25 females and 21 males) who were previously thyroidectomized and had received therapeutic doses of radioiodine. Serum Tg was assayed by IRMA and 16 patients were excluded because of interfering anti-Tg auto-antibodies. Of the remaining 30 patients, nine individuals had a positive whole body scan. Those subjects had low serum Tg levels while on suppressive doses of LT4 (Tg less than 2.8 ng/mL) but elevated when off LT4 (16-100 ng/mL). In the remaining patients with negative WBS serum Tg was below 3.2 ng/mL either on or off LT4 suppressive therapy. They concluded that a negative WBS associated with low serum Tg levels on or off LT4 is an excellent sign of good prognosis. The epidemiology of thyroid cancer was retrospectively evaluated in a Chilean province (Valdivia) by Pilleux and collaborators (Valdivia, Chile). They found 70% of papillary cancer, 12% of follicular cancer and also anaplastic (7.7%) and medullary (7.4%) carcinomas in a period of 10 years (1985-1995, total 65 cases or 1.79 new cases/100,00 inhabitants). The male/female ratio was 1:5, with a mean age of appearance of 47.5 years. The patients were submitted to total thyroidectomy with a follow-up period of 1 to 108 months (mean 33 months). The probability of survival at 60 months was estimated to be 75%, excluding the undifferentiated type of cancer. The introduction of an effective salt iodination program modifies the relative prevalence of subtypes of differentiated thyroid cancer, according to Perinetti et al. (Mendoza, Argentina). The incidence and pathology of the thyroid carcinoma was analyzed in 425 patients subdivided by decades (1951 through 1990). The type of thyroid tumor was compared in patients born before 1952 (before iodine prophylaxis) or after 1952 (when salt iodination was introduced). After 40 years of continuous supply of iodine a relative and absolute decline of follicular cancer incidence was confirmed. Simultaneously there was a significant increase in papillary cancer and almost no new cases of undifferentiated thyroid cancer were seen. The authors comment that these features have been observed in other geographically similar regions of the World but the link between iodine deficiency and the histological prevalence of thyroid cancer is not entirely clear. Cerebral metastases are extremely rare in papillary thyroid carcinoma. Roccatagliata and co-authors (Buenos Aires, Argentina) presented the case of a 70y-old female patient previously operated (total thyroidectomy) for a papillary thyroid cancer who developed signs and symptoms of a cerebral hemorrhage after the therapeutic doses of radioiodine. Imaging by MRI identified a cerebral tumor that was subsequently removed and stained positively for thyroglobulin. Remarkably serum Tg was continuously within the normal range throughout the follow-up. Moreover the cerebral tumor did not concentrate the tracer dose at the WBS. The prevalence of this rare localization is about 1.4% of reported patients. Controversies concerning staging of thyroid tumors were discussed by Rosa and co-authors (S&atild;o Paulo, Brazil). They analyzed 570 patients with a post-surgery diagnosis of differentiated thyroid carcinoma subdivided in a modified TNM classification: stage I; single nodule, stage II; lymph node metastases, stage III; capsule invasion, stage IV; distant metastases. After 30 years of follow-up patients in stage I had 90% survival rate, stage II 80%, stage III 52% and stage IV 10%. These values can be used to set a prognosis in other thyroid cancer series. The same group analyzed the results of surgery in 605 cases of thyroid cancer followed-up from 1-32 years. At the end of the observation period 80 patients had died of the disease. The actual survival possibilities were estimated to be 90% for the 278 patients with papillary carcinoma, 85% for the 227 individuals with follicular cancer, 65% for the solitary medullar cancer (n = 48) and only 10% for undifferentiated (anaplastic) thyroid cancer. They compare those relative survival rates with other reports and concluded that they were very similar. Molecular detection of p53 mutations in archival thyroid tumors was reported by Cerrutti and co-workers (São Paulo, Brazil). DNA was extracted from 11 paraffin-embedded thyroid carcinomas (8 papillary, 2 undifferentiated and one follicular). PCR amplification of the region corresponding to exons 5 to 8 of the p53 gene was performed, and screened for mutations using a SSCP technique (electrophoresis followed by silver staining). p53 suppressor gene mutations were suggested by abnormal bands in 2 undifferentiated cancers, 2 papillary and the only follicular cancer studied. DNA sequencing confirmed the point mutation in two of the tissues. The authors concluded that p53 mutations are frequently found in undifferentiated thyroid cancers but may also be found in papillary and follicular tumors. Familial medullary thyroid cancer (FMTC) and MEN 2A can be diagnosed by mutations in the ret proto-oncogene according to a report by Roque and co-authors (Mendoza, Argentina). It is well known that mutations in the ret oncogene are frequently found in FMTC and MEN 2A. In three families with MEN-2A, genomic DNA was obtained from most members and investigated for mutations in exon 11 of the ret gene. All the affected individuals had a point mutation in the ret gene as indicated by restriction analysis. In three relatives with a negative calcitonin test the same ret mutation was present. The authors comment on the usefulness of this methodology for early detection of individuals that carry this mutation and should be considered for surgical treatment. Elevated serum calcitonin levels were observed after surgery for medullary carcinoma as indicated by Gonzalez and cols. (Mexico DF, Mexico). A group of eight female patients (mean age 35y) was submitted to thyroid surgery after a careful protocol for study of medullary thyroid cancer. In six patients a gradient of serum calcitonin level was established between the jugular vein and the forearm vein. This was considered as indicative of cervical lymph node metastases and extensive extirpation of cervical nodes was recommended (lymph nodes removed: 18 to 33). In four patients serum CT level normalized in the post-surgery follow-up. In two of these patients the serum CT is still normal. In the remaining two patients there was indication for extracervical metastases and they were not submitted to surgery. The authors comment that selective catheterisation might be useful for the prognosis of the outcome of the treatment of thyroid medullary carcinoma.