Frequent loss of heterozygosity on chromosomes 3p and 17p without VHL or p53 mutations suggests involvement of unidentified tumor suppressor genes in follicular thyroid carcinoma

Follicular thyroid carcinoma (FTC) exhibits frequent loss of heterozygosity (LOH) on chromosomes 10q and 3p, suggesting involvement of tumor suppressor genes. We screened 14 FTC (10 Hurthle cell carcinomas and 4 nonoxyphilic FTC), 14 papillary thyroid carcinomas, and 7 follicular adenomas for LOH on chromosome arms 1p, 3p, 3q, 10p, 10q, 11p, 11q, 13q, 17p, and 17q. LOH was more frequent in FTC than in follicular adenoma or papillary thyroid carcinoma. In FTC, rates of LOH on 3p (86%), 17p (72%), and 10q (57%) were higher than the average rate of LOH (33%; P < 0.05). Most frequently involved were 3p21-25 and 17p13.1-13.3, the sites for the VHL (3p25-26) and p53 (17p13.1) tumor suppressors. We, therefore, characterized these genes by dideoxy fingerprinting and DNA sequencing. Two FTC had mutations in p53, but only 1 of these exhibited LOH at 17p. No VHL gene mutations were found. Thus, neither p53 nor VHL genes play a significant role in the pathogenesis of differentiated thyroid cancer. LOH on 17p, but not on 3p or 10q, was correlated with mortality. Accordingly, 3p and 10q LOH may represent early, and 17p LOH late, events in FTC development. The data suggest the presence of novel tumor suppressor genes on chromosomes 3p and 17p that may be important in the pathogenesis of FTC.

Extracervical fibrosclerosis causing obstruction of a ventriculo-peritoneal shunt in a patient with hydrocephalus and invasive fibrous thyroiditis (Riedel's struma)

The association of invasive fibrous thyroiditis (IFT) with foci of extracervical fibrosclerosis is well recognized. Affected sites include the retroperitoneum, the mediastinum, the biliary tract, and the orbit. The development of subcutaneous fibrosclerosis, however, is extremely rare. We report a patient with known invasive fibrous thyroiditis and hypoparathyroidism who presented with localized subcutaneous fibrosclerosis of the anterior chest wall resulting in compression of his ventriculoperitoneal shunt. The aetiology of IFT has remained unclear. Several histological and serological features, including the presence of mononuclear cells within the fibrosclerotic process, the occurrence of microscopic vasculitis, and the detection of autoantibodies directed against thyroid-specific antigens in a large proportion of patients with IFT, currently support the notion of autoimmune mechanisms playing a role in the pathogenesis of this rare disease.

Follicular and Hürthle cell thyroid neoplasms. Is frozen-section evaluation worthwhile?

OBJECTIVES

To determine whether (1) frozen-section (FS) evaluation of follicular and Hürthle cell thyroid neoplasms (FHCNs) is accurate, (2) FS aids in intraoperative decision-making, and (3) FS is cost-effective.

DESIGN

Retrospective review of patient histories and FS and paraffin-embedded slides. Permanent histologic sections were considered the standard criterion. Follow-up was achieved in 92% of patients with a mean follow-up of 5.7 years.

SETTING

Tertiary care referral center.

PATIENTS

All patients undergoing thyroidectomy for a suspected FHCN between January 1, 1985, and December 31, 1994. Patients included were those whose condition was diagnosed as FHCN, either on FS, permanent histologic sections, or both.

MAIN OUTCOME MEASURES

Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of FS analysts were determined. Total adjusted hospital charges were compared for those undergoing 1 vs 2 cancer operations. Multivariate analyses were carried out to determine the optimal predictive model for follicular cancer.

RESULTS

The study group included 1023 patients (737 women and 286 men), of whom 83 (8.1%) were diagnosed as having a malignant FHCN on permanent section. The diagnosis of malignant neoplasm was correctly established in 65 (78%) of the 83 patients on FS, thereby permitting definitive surgical management at the first operation. Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy for FS diagnosis of malignant FHCN were 78%, 99%, 90%, 98%, and 98%, respectively. In a multivariate analysis, FS was the most significant variable predictive of malignant neoplasm. Approximately $400,000 was saved in hospital charges by the use of FS as a result of the elimination of many 2-stage operations.

CONCLUSION

Frozen-section evaluation of FHCN can be performed with a high degree of accuracy, permitting considerable cost savings.

Thyroglossal duct carcinoma: report of 12 cases

OBJECTIVE

To report the relative frequency, natural history, and optimal treatment of thyroglossal duct (TGD) carcinoma.

DESIGN

We retrospectively reviewed all cases of TGD carcinoma surgically treated during a 44-year period at a tertiary referral center.

MATERIAL AND METHODS

The computerized medical records database at Mayo Clinic Rochester was searched for patients who had the diagnosis of TGD carcinoma or TGD cyst carcinoma from 1950 through 1994. Medical records and pathologic specimens of these patients were reviewed.

RESULTS

Twelve patients (six male and six female patients), who were 17 to 60 years old (mean, 40), were identified. The frequency of TGD carcinoma among surgically removed TGD cysts was 0.7%. A midline upper neck mass was the initial symptom in all patients. The diagnosis of cancer was made after the Sistrunk procedure in 11 of 12 cases and preoperatively (by fine-needle aspiration biopsy) in only 1 case. All patients had papillary carcinoma. Thyroid involvement was noted in three cases. Nine patients had subtotal or near-total thyroidectomy, and three received postoperative radioactive iodine. After a mean follow-up of 13 years (range, 1 to 38), no patient had a documented local recurrence or distant metastatic involvement, and no tumor-associated mortality was observed.

CONCLUSION

TGD carcinoma is a rare malignant tumor that is usually diagnosed postoperatively. Papillary carcinoma is the most common pathologic finding. The recommended treatment is the Sistrunk procedure followed by near-total or total thyroidectomy by a skilled thyroid surgeon because of the possibility of intrathyroidal foci of cancer. The prognosis is excellent in patients with papillary tumor.

Thyroid carcinoma metastatic to the skin: a cutaneous manifestation of a widely disseminated malignancy

BACKGROUND

Cutaneous metastases develop in 2% to 9% of patients with an internal malignancy. Thyroid carcinoma metastatic to the skin is a rare clinical entity.

OBJECTIVE

Our purpose was to study the clinical and pathologic features and outcome in patients with cutaneous metastasis from thyroid carcinoma.

METHODS

The study included a retrospective analysis of six patients with skin metastases from thyroid carcinoma and a review of the English-language literature since 1964.

RESULTS

Including our six patients, 43 patients with skin metastases from thyroid carcinoma have been reported. Papillary carcinoma was the most common (41%), followed by follicular (28%), anaplastic (15%), and medullary carcinomas (15%). The scalp was the most common site of metastasis. For our patients, the average length of survival after diagnosis of cutaneous metastasis was 19 months.

CONCLUSION

Cutaneous metastasis from thyroid carcinoma is rare and occurs in the setting of disseminated neoplastic disease.

Insular thyroid carcinoma in adolescents: a potentially lethal endocrine malignancy

BACKGROUND

Insular thyroid carcinoma is intermediate in aggressiveness between well differentiated and anaplastic thyroid carcinomas.

METHODS

The authors describe two children with insular thyroid carcinoma who had markedly different outcomes. In the first case, a girl age 15 years, 2 months presented with a large pulsatile mass in the right thyroid lobe. In the second case, a girl age 16 years, 3 months presented after total thyroidectomy was performed elsewhere for confirmed pTNM Stage I insular thyroid carcinoma.

RESULTS

In Case 1, total thyroidectomy was performed, and histologic examination revealed insular thyroid carcinoma with lymph node involvement. Six weeks postoperatively, neck masses reappeared. There was significant radioactive iodine uptake in the thyroid bed and in a palpable right supraclavicular lymph node; this was associated with an increased serum thyroglobulin level. Ultrasound-guided biopsy of the lymph node confirmed recurrent insular carcinoma, and neck dissection was performed. Six weeks later, there was 0.35% iodine uptake in the neck, and the patient was treated with 300 mCi of (131)I. She had no signs of recurrence when last seen 22 months postoperatively. In Case 2, the patient was given 29.9 mCi of (131)I for remnant ablation. Four months postoperatively, fine-needle aspiration biopsy of a high jugular lymph node demonstrated recurrence. The patient was given 200 mCi of (131)I but had no significant response. Right modified neck dissection was performed, followed by external beam radiation. Despite aggressive treatment with a further 500 mCi of (131)I, progressive lung and mediastinal metastases developed, followed by brain metastasis. The patient died 31 months after the initial diagnosis.

CONCLUSIONS

Insular thyroid carcinoma may occur and behave aggressively in children. Vigorous initial surgical and radioactive iodine treatments are warranted.

The effect of the treatment of hypothyroidism and hyperthyroidism on plasma lipids and apolipoproteins AI, AII and E

OBJECTIVE

Although lipid abnormalities are well described in hypothyroidism, effects on apolipoproteins are less well understood. The aim of this study was to examine the effects of thyroid dysfunction on plasma lipids and apolipoproteins.

DESIGN

A prospective study of lipids and apolipoproteins before and after treatment of hypothyroidism and hyperthyroidism.

PATIENTS

Eighteen patients with hypothyroidism and 5 patients with hyperthyroidism were included.

MEASUREMENTS

Plasma cholesterol, triglycerides, HDL cholesterol, apo AI, apo AII, and apo E were measured before and after treatment of the thyroid abnormality.

RESULTS

Total and HDL cholesterol, apo AI and apo E decreased with treatment of hypothyroidism, while triglycerides and apo AII levels were unchanged. The total/HDL cholesterol and LDL/HDL cholesterol ratios also decreased with treatment of hypothyroidism. In contrast, treatment of hyperthyroidism was associated with an increase in total and HDL cholesterol, and apo AI. Triglycerides, apo AII and Apo E were unchanged by treatment of hyperthyroidism. The total/HDL cholesterol and the LDL/HDL cholesterol ratios increased with treatment of hyperthyroidism.

CONCLUSIONS

Hypothyroidism and hyperthyroidism have opposite effects on plasma lipids and apolipoproteins. In hypothyroidism, total and HDL cholesterol, total/HDL cholesterol ratio, apo AI and apo E are elevated. The increase in apo AI without a concomitant increase in apo AII suggests selective elevation of HDL2. In contrast, hyperthyroidism is associated with decreased total and HDL cholesterol, total/HDL cholesterol ratio, and apo AI levels. These effects are reversible with treatment of the underlying thyroid disorder.

Columnar cell carcinoma of the thyroid: report of three additional cases

Columnar cell carcinoma is a recently described variant of thyroid carcinoma that has been associated with an aggressive clinical course. The authors describe three new cases of columnar cell carcinoma occurring in two women and one man aged 62, 46, and 46 years, respectively. The tumors ranged in size from 1 to 7.5 cm, and two of the tumors were associated with distant metastases. One patient died of disease 39 months after presentation. Another patient is alive with distant metastases 27 months after diagnosis. One patient appears to be a long-term survivor with no evidence of metastasis after follow-up of 22 years. This patient had a tumor that was small (1 cm) and encapsulated. DNA ploidy analysis in two tumors showed diploid DNA content, and there was no elevated S phase. All tumors were positive for thyroglobulin and negative for calcitonin and carcinoembryonic antigen (CEA). These findings support the original observation that columnar cell variants of papillary thyroid carcinoma are usually aggressive neoplasms. There does not appear to be an increased incidence of DNA aneuploidy in columnar cell carcinomas to account for their more aggressive behavior. These tumors occur over a wide age range, can metastasize widely, and are not usually responsive to radioactive iodine or chemotherapy.

Tissue eosinophilia and eosinophil degranulation in Riedel's invasive fibrous thyroiditis

The etiology of Riedel's invasive fibrous thyroiditis (IFT) has remained obscure. This rare disorder has been confused in the past with the more common fibrous variant of Hashimoto's disease. The typical histological features of IFT, in particular the presence of an invasive fibrosclerotic process in conjunction with a prominent chronic inflammatory infiltrate, suggest that the release of fibrogenic cytokines and other factors from these cellular infiltrates may play an important role in the pathogenesis of this condition. Our observations in routinely processed tissue sections obtained from patients with documented IFT of striking tissue eosinophilia led us to hypothesize that eosinophils and their products may play a role in the evolution of this disease. Immunofluorescence staining with affinity-purified polyclonal rabbit antibody directed against human eosinophil granule major basic protein revealed marked tissue eosinophilia and abundant extracellular deposition of major basic protein in all specimens from 16 patients with IFT. By contrast, only occasional eosinophils and no extracellular major basic protein were detected in control thyroid tissues obtained from patients with multinodular goiter, Graves' disease, Hashimoto's disease, and normal thyroid tissue. The presence of marked eosinophil infiltration and extracellular major basic protein deposition in IFT and other associated fibrosclerotic conditions suggests a role for eosinophils and their products in propagating the fibrogenesis seen in IFT.

Thyroid cancer nodal metastases: biologic significance and therapeutic considerations

Lymph node metastases at presentation are common in PTC and MTC (about one third of patients at presentation), but are rare in other types of thyroid malignancy, though HCC frequently recurs in lymph nodes. Nodal metastases can be detected by a variety of means, but high resolution ultrasonography may be the method of choice. Unlike other epithelial malignancies, in thyroid cancer neither prognostic significance nor optimal treatment of nodal metastasis are known with certainty. For PTC lymph node metastases at presentation do not seem to adversely affect survival, but do increase the risk of locoregional tumor recurrence. By contrast, in FTC nodal metastases at presentation may adversely affect cause-specific mortality, but because of their rarity definite conclusions are impossible. Except for the oxyphilic variant of FTC (HCC) nodal recurrence in FTC is rare. The most firm evidence of prognostic relevance for nodal metastases in thyroid malignancies exists in medullary thyroid cancer, where most studies suggest that survival and recurrence are both adversely affected by node-positive status at presentation. Primary treatment of nodal metastases is removal of macroscopically affected nodes at initial surgery, optionally supplemented with adjuvant radioiodine treatment in an attempt to reduce recurrence risk. The value, however, of postoperative radioiodine in preventing either nodal recurrence or cancer death in patients with papillary and follicular thyroid cancer remains controversial. Extensive lymph node dissection at presentation offers no advantage (and may cause increased morbidity) in papillary carcinoma, but may be useful in medullary thyroid carcinoma, where nodal metastases seem to increase the risk of cause-specific mortality. In all tumor types postoperative nodal recurrences should primarily be treated surgically.

Follicular thyroid cancer

Follicular thyroid cancer is the second most common thyroid malignancy after PTC. There are marked geographical variations in the relative proportions of FTC and PTC, most likely related to dietary iodine content. In iodine-deficient areas, the relative rate of FTC tends to be increased. Other risk factors for FTC include age over 50 years and female sex. Genetic factors may also have a role in determining disease susceptibility but remain ill-defined. Histologically, FTC is characterized by follicle formation and the absence of any papillary elements in the tumor. Differential diagnosis from a benign adenoma can be difficult. The degree of vascular invasiveness seems to correlate with tumor aggressiveness, and two histologic subtypes, oxyphilic FTC and insular FTC, may be associated with increased morbidity and mortality. Primary treatment for FTC is complete surgical tumor removal. Extensive bilateral surgery beyond this goal may not confer additional benefit but can facilitate adjuvant treatment and follow-up. Postoperative levothyroxine treatment is almost universally used, and patients deemed at high risk of recurrence may benefit from radioiodine remnant ablation. Treatment of metastatic disease involves operation, radioiodine, and, in selected cases, external beam radiation and chemotherapy. Prognosis for patients with metastatic disease is guarded, but most other patients have good outcomes comparable to that in PTC. For nonoxyphilic FTC, high-risk features other than initial metastases include advanced age, locally extensive disease, and the presence of marked angioinvasion. In oxyphilic FTC, DNA aneuploidy is also important. Follow-up should be most intense during the first 5 years after primary treatment and needs to be tailored to the patient's risk of disease progression. For patients at low risk of recurrence (young, small lesions, minimally invasive tumor), serum thyroglobulin measurements may largely suffice, whereas higher risk patients with elevated serum thyroglobulin levels and patients with significant titers of interfering anti-thyroglobulin autoantibodies may also need to undergo periodic diagnostic radioiodine scanning.

Distant metastases in papillary thyroid carcinoma: 100 cases observed at one institution during 5 decades

The present study was designed to define the factors that predict survival in patients with distant metastases (DM) from papillary thyroid carcinoma. We performed a retrospective review of the records of 100 consecutive patients (45 females and 55 males; age range, 8-91 yr) who developed DM after primary treatment at our institution from, 1940-1989. Median follow-up for the 20 survivors was 21 yr (range, 3-38). Cause-specific survival rates at 5, 10, and 15 yr were 40%, 27%, and 24%, respectively, and were not significantly different between the eras 1940-1954, 1955-1969, and 1970-1989 (P = 0.74). By univariate analysis, age at diagnosis of DM was the most important predictor of survival (P < 0.0001), with improved survival occurring in younger patients. Tumor-related factors associated with improved survival included complete resection of the primary tumor (P < 0.005), histological grade 1 (P = 0.006), diploid nuclear DNA (P = 0.03), and lung as first site of DM (P = 0.018). By univariate analysis, use of radioiodine therapy was associated with improved survival (vs. other forms of therapy, P < 0.001). However, by multivariate analysis only age, site of DM, and degree of extrathyroidal invasion of the primary tumor were identified as significant predictors of survival. None of the four treatment variables (external radiation, surgery, chemotherapy, or radioiodine) was a significant predictor of survival in the Cox model. Our retrospective data indicate that 1) outcome has changed little over 5 decades for patients with DM from papillary thyroid carcinoma; and 2) current forms of therapy do not appear to impact on survival.

Medullary thyroid carcinoma in multiple endocrine neoplasia types 2A and 2B

BACKGROUND

Considerable emphasis has been placed on early diagnosis and surgery for multiple endocrine neoplasia (MEN)-related medullary thyroid carcinoma (MTC) during the past two decades. Genetic screening now promises earlier and more accurate diagnosis. We examine our experience with MTC in MEN 2A and MEN 2B and assess the benefits of biochemical screening during the past 20 years.

PATIENTS AND METHODS

Seventy-seven patients undergoing 63 primary total thyroidectomies and 14 reoperative procedures for MEN-related invasive MTC and/or preinvasive C-cell hyperplasia are reported. Fifty-eight patients had MEN 2A and 19 had MEN 2B; 79% of patients had a family history of MTC; 27% had pheochromocytoma, and 25% had hyperparathyroidism.

RESULTS

Patients with MEN 2B had more advanced disease than those with MEN 2A, in spite of presentation at a younger age (15 years versus 24 years). Every patient with MEN 2B had invasive carcinoma, whereas 14% of patients with MEN 2A had C-cell hyperplasia without invasive disease. Nodal metastases were found less frequently in MEN 2A (14%) than MEN 2B (38%), and biochemical cure was achieved in 56% of patients with MEN 2A compared with none in patients with MEN 2B. Among patients with MEN 2A the occurrence of invasive carcinoma increased with age (p = 0.0003); 40% of patients for less than 5 years had invasive MTC compared with 100% at more than 20 years. Cause-specific mortality among patients with MEN and invasive tumors at 6, 12, and 18 years was 2%, 4%, and 7%, respectively, lower than that of patients with sporadic MTC (12%, 17%, and 23%, respectively) treated during the same time period (p = 0.028).

CONCLUSIONS

Intensive biochemical screening of MEN 2 kindreds for MTC can result in detection of early disease and a significant prospect of surgical cure. Genetic testing promises additional benefits through more reliable detection of preinvasive disease, allowing prophylactic thyroidectomy in infancy. In MEN 2B, MTC is considerably more aggressive than in MEN 2A. A policy of routine thyroidectomy in infants with MEN 2B, regardless of serum calcitonin levels, is justified.

Evidence for autoimmune mechanisms in the evolution of invasive fibrous thyroiditis (Riedel's struma)

The etiology of Riedel's invasive fibrous thyroiditis, a rare disorder confused in the past with the more common fibrous variant of Hashimoto's disease, has remained obscure. However, the presence of mononuclear cells in the fibrosclerotic process and the detection of autoantibodies directed against thyroid-specific antigens in a large proportion of patients with invasive fibrous thyroiditis favor an autoimmune pathogenesis of invasive fibrous thyroiditis. Further, an association between invasive fibrous thyroiditis and Hashimoto's thyroiditis has been suggested. Here we report the first two patients in whom invasive fibrous thyroiditis evolved from antecedent Graves' disease, documented by the presence of thyroid dysfunction, bilateral ophthalmopathy, and thyrotropin receptor stimulating autoantibodies. The diagnosis of invasive fibrous thyroiditis was established in both instances on the basis of the established histopathological criteria. The presence of extensive mononuclear cell infiltration within the invasive fibrosclerotic process in these two patients, the close relationship between thyroid-specific autoantibodies, inflammatory parameters, and disease activity, and the response to glucocorticoid therapy all suggest the existence of a link between Graves' disease and invasive fibrous thyroiditis. These findings support the notion of autoimmune mechanisms playing a role in the pathogenesis of Riedel's invasive fibrous thyroiditis.

Locally invasive papillary thyroid carcinoma: 1940-1990

Well-differentiated thyroid carcinoma infrequently invades the upper aerodigestive tract. However, when invasion occurs, it is the source of significant morbidity. The most common structures invaded by thyroid carcinoma are the recurrent laryngeal nerves, larynx, pharynx, and esophagus. Invasion of these structures produces symptoms of airway insufficiency, dysphagia, and hemoptysis. This study was designed to define more clearly the significance of invasion of papillary thyroid carcinoma on survival. At the Mayo Clinic, 262 patients treated for invasive papillary thyroid carcinoma between 1940 and 1990 were retrospectively evaluated. In this group the sites of invasion were muscle 53%, trachea 37%, laryngeal nerve 47%, esophagus 21%, larynx 12%, and other sites 30%. Complete tumor removal was accomplished in 56% of cases. Kaplan-Meier survival curves were calculated for the population. The overall survival was 79% at 5 years, 63% at 10 years, and 54% at 15 years. When the Cox proportional hazard model was applied to the survival data, the factors that had significant influence on survival were invasion of the trachea and the esophagus. Completeness of resection approached statistical significance. Muscle invasion, laryngeal invasion, and recurrent laryngeal nerve invasion had no significant independent influence on survival. These data suggest that when papillary thyroid carcinoma extends beyond the thyroid capsule and invades adjacent structures, the site invaded will influence survival. Survival may be improved in those cases in which complete surgical excision of the tumor is performed.

Paraneoplastic cholestasis and hypercoagulability associated with medullary thyroid carcinoma. Resolution with tumor debulking

The authors report a 69-year-old woman with a hypercoagulable state manifesting as superior sagittal sinus thrombosis, thrombocytosis, right lower extremity deep venous thrombosis, and subsequent pulmonary embolus. The liver enzyme values were elevated in a cholestatic pattern. Carcinoembryonic antigen level was markedly elevated. Evaluation revealed that her longstanding "goiter" had slowly enlarged during the past 6 years. The serum calcitonin level was markedly elevated. Subsequent biopsy revealed medullary thyroid carcinoma. Surgical debulking of the tumor and lymph nodes resulted in substantial reduction of the calcitonin and carcinoembryonic antigen levels in a matter of days. Long-term follow-up revealed normalization of cholestasis and resolution of the hypercoagulable state. Review of the literature revealed no previously reported cholestasis or hypercoagulable state associated with medullary thyroid carcinoma. The literature on paraneoplastic cholestasis, carcinoembryonic antigen production, and hypercoagulable states is reviewed.

Predicting outcome in papillary thyroid carcinoma: development of a reliable prognostic scoring system in a cohort of 1779 patients surgically treated at one institution during 1940 through 1989

BACKGROUND

Multivariate analyses in papillary thyroid carcinoma (PTC) have shown that age, tumor size, local invasion and distant metastasis are independent predictive variables. This study attempted to define a reliable prognostic scoring system for predicting PTC mortality rates with 15 candidate variables that included completeness of primary tumor resection but excluded histologic grade and DNA ploidy.

METHODS

The study group comprised 1779 patients with PTC (followed up for > 26,000 patient-years), divided by treatment dates into 1940 to 1964 (n = 764) and 1965 to 1989 (n = 1015). Cox model analysis and stepwise variable selection led to a prognostic model initially derived from the training set (n = 764). The initial prognostic score was thereafter validated externally with the later (1965 to 1989) "test" data set.

RESULTS

The final model included five variables abbreviated by metastasis, age, completeness of resection, invasion, and size (MACIS). The final prognostic score was defined as MACIS = 3.1 (if aged < or = 39 years) or 0.08 x age (if aged > or = 40 years), + 0.3 x tumor size (in centimeters), +1 (if incompletely resected), +1 (if locally invasive), +3 (if distant metastases present). Twenty-year cause-specific survival rates for patients with MACIS less than 6, 6 to 6.99, 7 to 7.99, and 8+ were 99%, 89%, 56%, and 24%, respectively (p < 0.0001).

CONCLUSIONS

Because the five variables needed for MACIS scoring are readily available after primary operation, such a prognostic system could have widespread applicability in assessment of PTC.

Expression of a potential metastasis suppressor gene (nm23) in thyroid neoplasms

Identification of multiple clinical and pathologic prognostic factors in differentiated thyroid cancer has permitted some degree of risk stratification. However, these clinical indices fail to distinguish potential intrinsic differences in tumor virulence. The nm23 gene has been identified as a potential metastasis suppressor gene that is homologous to nucleoside diphosphate kinases. Studies in human breast cancer have shown a significant inverse correlation between nm23 levels and nodal involvement/tumor recurrence. Given the possible clinical utility of a marker of metastatic potential in the management of thyroid carcinoma, we examined 34 thyroid neoplasms and a human medullary thyroid cancer (MTC) cell line (TT) for nm23 expression. Normalized nm23 expression was assessed by Northern analysis of tumor RNA. nm23 Expression (tumor expression/TT cell expression, mean +/- SE) was 1.14 +/- 0.15* in MTCs (n = 5), 0.70 +/- 0.10* in follicular cancers (n = 6), 0.51 +/- 0.11 in papillary cancers (n = 19), and 0.31 +/- 0.03 in follicular adenomas (n = 4) (*p < 0.05 when compared to adenomas). Within histologic groups, we found no correlation between nm23 expression and nodal involvement of distant metastases. Our results indicate that thyroid neoplasms of different histologies express varying levels of the nm23 transcript. Although nm23 expression seems diminished in metastatic breast cancer, it appears not to be the case in metastatic thyroid cancer. The nm23 gene may therefore have different roles in the evolution and metastases of different neoplasms.