TSH suppression in the management of thyroid nodules and thyroid cancer

Thyroid hormones for euthyroid patients with simple goiter growing over time: a survey of European thyroid specialists

BACKGROUND

Treatment of simple goiter (SG) growing over time with thyroid hormone (TH) therapy is discouraged by international guidelines.

PURPOSE

To ascertain views of European thyroid specialists about TH treatment for euthyroid patients with growing SG and explore associations with management choice.

METHODS

Online survey on the use of TH for growing SG among thyroid experts from 28 European countries.

RESULTS

The response rate was 31.5% (5430/17,247). Most respondents were endocrinologists. Twenty-eight percent asserted that TH therapy may be indicated in euthyroid patients with a growing SG. National and regional differences were noted, from 7% of positive responses in The Netherlands to 78% in Czech Republic (p < 0.0001). TH was more frequently prescribed by respondents over 40 years old (OR 1.77, 2.13, 2.41 if 41-50, 51-60, >60, respectively), and working in areas of former iodine insufficiency (OR 1.24, 95% CI 1.03-1.50). TH was less frequently prescribed by endocrinologists (OR 0.77, 95% CI 0.62-0.94) and respondents working in Southern Europe (OR 0.40, 95% CI 0.33-0.48), Northern Europe (OR 0.28, 95% CI 0.22-0.36) and Western Asia (OR 0.16, 95% CI 0.11-0.24) compared to Western Europe. Associations with respondents' sex, country, availability of national thyroid guidelines, and gross national income per capita were absent or weak.

CONCLUSIONS

Almost a third of European thyroid specialists support treating SG with TH, contrary to current guidelines and recommendations. This calls for urgent attention.

Multi-targeted approach in the treatment of thyroid cancer

While accounting for only 1% of solid organ malignancies (9% in women), thyroid carcinoma is the most common malignancy of the endocrine system. Although most patients have a favorable prognosis, over 1,500 people will die from thyroid carcinoma each year. The spectrum of disease types range from papillary thyroid cancer, which is a well-differentiated indolent tumor, to anaplastic carcinoma, a poorly differentiated fulminant cancer. With advances in diagnostic methods, surgical techniques, and clinical care of patients with thyroid carcinoma, the current management of thyroid cancer demands a multidisciplinary approach. The majority of patients with well-differentiated thyroid carcinoma of follicular cell origin are cured with adequate surgical management; however, some thyroid malignancies such as medullary thyroid carcinoma (MTC) or poorly differentiated thyroid carcinomas frequently metastasize, precluding patients from a curative resection. As such, novel palliative and therapeutic strategies are needed for this patient population. Here, we explore the current management of thyroid carcinoma, including surgical management of the primary tumor, lymph node disease, and locoregional recurrence. Likewise, we explore the application of current molecular techniques, reviewing nearly two decades of data that have begun to elucidate critical genetic pathways and therapeutic drug targets which may be important in specific thyroid tumor types.

Surgical treatment of thyroid diseases in elderly patients

BACKGROUND

We evaluated the safety of thyroid surgery in elderly patients, in whom surgical procedures usually are considered more hazardous than in younger patients.

METHODS

The medical records of all the patients who were aged 70 years or older who had undergone thyroid surgery between January 1998 and June 2008 were reviewed.

RESULTS

A total of 320 patients were included. The preoperative diagnosis was multinodular goiter in 171 cases, toxic goiter in 59 cases, suspicious or indeterminate thyroid nodule in 60 cases, and thyroid carcinoma in 30 patients. Total thyroidectomy was performed in 283 patients, thyroid lobectomy in 15 patients, and a completion thyroidectomy was performed in 22 patients. The final histology showed thyroid cancer in 86 patients and benign disease in 234.

CONCLUSIONS

Thyroid surgery in patients aged 70 years or older is safe and the relatively high rate of thyroid carcinoma and toxic goiter may justify an aggressive approach.

Evaluation of suppressive therapy for cold thyroid nodules with levothyroxine: double-blind placebo-controlled clinical trial

OBJECTIVE

To study the efficacy of levothyroxine suppressive therapy in the management of benign thyroid nodules.

METHODS

We performed a double-blind clinical trial comparing levothyroxine treatment (1.5 to 2.0 mg/kg of body weight daily) (N = 32) with placebo (N = 30) for a 1-year period in patients with a benign, cold thyroid nodule confirmed by biopsy and 99mTc-pertechnetate scanning, who were randomly assigned to the treatment or control group. High-resolution sonography was used to measure the size of the nodules before and after the treatment. Suppression of thyrotropin was evaluated by the administration of thyrotropin-releasing hormone to 10 patients randomly in each group.

RESULTS

The mean volume of the thyroid nodules decreased significantly after 6 months in both the levothyroxine group (from 12.8 +/- 11.9 mL to 9.4 +/- 9.8 mL; P = 0.003) and the placebo group (from 13.2 +/- 10.2 mL to 11.5 +/- 8.0 mL; P = 0.003). After 12 months, however, the volume of the nodules had increased. Thus, no significant decrease was found in the mean nodule volume in either study group at 1 year in comparison with the mean volume at baseline (final mean volume: 12.4 +/- 16.7 mL in the levothyroxine group and 11.7 +/- 13.6 mL in the placebo group).

CONCLUSION

Suppressive therapy with levothyroxine for a period of 12 months proved to be ineffective in significantly reducing the size of the thyroid nodules in our patients despite effective suppression of the thyrotropin level.

Risk factors for recurrent nodular goiter after thyroidectomy for benign disease: case-control study of 244 patients

Surgery for recurrent nodular goiter is associated with a significant risk of parathyroid and recurrent laryngeal nerve (RLN) morbidity. Total thyroidectomy for benign disease is assessed. The aim of this study was to evaluate the risk factors for recurrence and the morbidity associated with reoperation. From 1969 to 1996 a total of 4334 thyroidectomies were performed, of which 122 were for recurrent nodular goiter (group I: 116 women, 6 men). A matched case-control study of 122 patients operated on for nonrecurrent multinodular goiter was performed (group II: 112 women, 10 men). Age, family history, initial surgery, pathology, and morbidity were compared in the two groups by chi2 test, Fisher's exact test, and the Mantel-Haenszel test. The mean age was 39.88 years in group I and 47.89 years in group II. There was no statistical difference in relation to the extent of thyroidectomy or morbidity after initial surgery. Statistical differences were identified regarding age (p = 0.000002) and the multinodular nature of the initial goiter (p = 0.005). Bilaterality and family history were less significant (p = 0.09 andp = 0.08, respectively). Temporary RLN palsy and temporary hypoparathyroidism were higher in group I (12.3% vs. 5.7%,p = 0.0737; 10.6% vs. 1.7%, p = 0.00337). Permanent RLN palsy was found in 0.8% in group I and in none in group II (p = 0.5, NS). Young age and multiple nodules at initial surgery are risk factors for recurrence. A higher rate of temporary morbidity was demonstrated after surgery for recurrent goiter. Total thyroidectomy for multinodular goiter is advisable.

Thyrotoxicosis due to metastatic papillary thyroid cancer in a patient with Graves' disease

Thyrotoxicosis resulting from functional thyroid cancer metastases is extremely rare, and is mostly caused by follicular cancer. The lesions causing thyrotoxicosis are usually bulky and extensive. We report here a patient with Graves' disease and concomitant papillary thyroid cancer who developed metastases causing symptomatic thyrotoxicosis. His serum titers of thyroid stimulating Ig (TSIs) were elevated. We believe that TSIs were responsible for thyrotoxicosis by stimulating hormonogenesis in the metastatic lesions.

Effects of thyroid hormone suppression therapy on adverse clinical outcomes in thyroid cancer

BACKGROUND

Long-term thyroid hormone (TH) therapy aiming at the suppression of serum thyrotropin (TSH) has been traditionally used in the management of well differentiated thyroid cancer (ThyrCa). However, formal validation of the effects of thyroid hormone suppression therapy (THST) through randomized controlled trials is lacking. Additionally, the role - if any - of TSH effect at low ambient concentrations upon human thyroid tumorigenesis remains unclear.

AIM

Evaluation of the effect of THST on the clinical outcomes of papillary and/or follicular ThyrCa.

METHODS

By using a quantitative research synthesis approach in a cumulative ThyrCa cohort, we evaluated the effect of THST on the likelihood of major adverse clinical events (disease progression/recurrence and death). A total of 28 clinical trials published during the period 1934-2001 were identified; only 10 were amenable to meta-analysis. Causality was assessed by Hill criteria.

RESULTS

Out of 4, 174 patients with ThyrCa, 2, 880 (69%) were reported as being on THST. Meta-analysis showed that the group of patients who received THST had a decreased risk of major adverse clinical events (RR = 0.73; Cl = 0.60-0.88; P < 0.05). Further, by applying a Likert scale, 15/17 interpretable studies showed either a 'likely' or 'questionable' beneficial effect of THST. Assessment of causality between TSHT and reduction of major adverse clinical events suggested a probable association.

CONCLUSIONS

THST appears justified in ThyrCa patients following initial therapy. As most primary studies were imperfect, future research will better define the effect of THST upon ThyrCa clinical outcomes.

Differentiated thyroid carcinoma in the elderly

The overall prognosis of patients with differentiated thyroid cancer is excellent, but the prognosis is rapidly worsening, when the disease is diagnosed in elderly patients. Old patients more often present with poor prognostic features, such as large tumors, follicular or Hürthle cell subtypes, extrathyroidal growth and distant metastases. Therefore, an optimal therapeutic approach is recommended. Current therapy includes a total thyroidectomy, if necessary combined with a lymph node dissection and followed by high dose radioiodine ablation. Radioiodine therapy in elderly patients meets specific problems, concerning thyroid hormone withdrawal, side effects of 131I and nursing problems. Additional treatment of residual, recurrent or metastatic disease must be tailored, according to the stage of the disease, and should not be denied on the basis of chronological age. Lifelong treatment with suppressive thyroid hormone therapy does not lead to important long-term side effects at old age.

Thyroid malignancy in endemic nodular goitres: prevalence, pattern and treatment

AIMS

The epidemiology of thyroid cancers in goitre endemic zones has not been recently reviewed, and changes being currently reported have been from studies in non-endemic areas. The aims of this study were to present the clinical pattern of thyroid malignancy in a goitre endemic area and identify recent changes, if any.

METHODS

The study was conducted at Obafemi Awolowo University Teaching Hospitals Complex, Ile-Ife, Nigeria between January 1983 and December 1993. Records of patients with nodular goitres treated with thyroidectomy were reviewed, and the clinical features, laboratory parameters, treatment, outcome and follow-up of histologically-proven malignant cases were studied.

RESULTS

Thirty-six of 279 (12.9%) patients, aged 13-85 years (mean)=43.7+/-14.7 years), carried malignant goitres, and most (80%) were young or middle-aged women. Of the well-differentiated cancers, follicular type was the most prevalent, being six- and 12-fold as frequent as papillary and medullary cancers (69%vs 11% and 5.6%), respectively. Lymphoma accounted for 5.6%, fibrosarcoma, 5.6% and anaplastic, 2.8%. No relationship was demonstrable between cancer type, duration of goitre and age at diagnosis (r=0.06 and 0.17, respectively).

CONCLUSIONS

Thyroid cancers afflict comparatively young women in our environment, and follicular cancer remains the predominant type, partly as a result of persisting dietary iodine deficiency.

Changes of expression level of the differentiation markers in papillary thyroid carcinoma under thyrotropin suppression therapy in vivo immunohistochemical detection of thyroglobulin, thyroid peroxidase, and thyrotropin receptor

BACKGROUND AND OBJECTIVES

Differences in the expression levels of Thyroglobulin (Tg), Thyroid peroxidase (TPO) and thyrotropin receptor (TSH-R) in primary and recurrent specimens under a suppressive serum TSH condition were elucidated in 26 papillary carcinoma patients.

METHODS

Immunohistochemical detection was performed by use of each monoclonal antibody against Tg, TPO, and TSH-R. The staining concentrations of the three markers in each specimen were measured for comparison.

RESULTS

The mean staining concentrations of Tg, TPO, and TSH-R in the entire primary tumor were 103.92, 104.6 and 89.25, respectively. Five cases showed stronger expression of all the differentiation markers and eight cases showed weaker expression of all these markers in recurrent tissue than in primary tumors. The weaker expression of TSH-R at the recurrent site as compared with that at the primary site significantly demonstrated the shortness of the disease free interval or overall survival. There were significant differences between the death due to cancer and the weaker expression of TSH-R in the recurrent tumor as compared with that in the primary tumor.

CONCLUSIONS

Under the TSH suppressive condition, the markers were not expressed uniformly among recurrent tumors. Even under that state, however, low expression of TSH-R in the recurrent tissue was strongly related to a poorer outcome in the patients.

Recurrent or persistent thyroid cancer of follicular cell origin

Most patients with differentiated thyroid cancer of follicular cell origin have a favorable postoperative course, and their prognosis often appears to be unrelated to the extent of initial surgical treatment in some studies. Important questions that need to be addressed include whether the extent of the initial operation has any impact on the subsequent tumor-free survival and total survival, and whether patients with persistent or recurrent disease benefit from reoperation.

Role of thyroid-stimulating immunoglobulin in aggressiveness of well-differentiated thyroid cancer

OBJECTIVE

To assess whether a relationship exists between thyroid-stimulating antibodies and increased aggressiveness of thyroid cancer.

METHODS

We analyzed clinical, histologic, and biochemical data, including thyroid-stimulating antibodies, from 26 patients (24 women and 2 men) who had had well-differentiated thyroid carcinoma for 1 to 5 years and had undergone total thyroidectomy and radioactive iodine ablative therapy. For analysis, the overall study cohort was divided into two groups: group 1 (N = 16), with stable disease and no evidence of metastatic activity, and group 2 (N = 10), with aggressive disease and substantiated metastatic involvement.

RESULTS

The thyroid-stimulating antibodies ranged from 92 to 129% in group 1 and from 95 to 118% in group 2. Thus, both study groups had thyroid-stimulating antibody levels within the normal range (normal, <130%).

CONCLUSIONS

Apparently, thyroid-stimulating antibodies had no contributory role in the growth of the metastatic lesions in the 10 patients with aggressive disease. Further studies should be undertaken to investigate other potential factors involved in stimulating the progression of thyroid cancer.

Follicular neoplasms: the role for observation, fine needle aspiration biopsy, thyroid suppression, and surgery

The diagnosis and management of follicular carcinoma of the thyroid gland remains a controversial topic. Fine needle aspiration, although very sensitive with other types of thyroid cancer, has limited accuracy with follicular lesions. The role of suppression combined with observation has yet to gain widespread acceptance. The extent of surgical excision of follicular carcinoma also raises several competing views. The goal of this review is to address these issues and present an algorithm for the management of follicular neoplasms of the thyroid.

Anaplastic transformation of a papillary carcinoma of the thyroid in a patient with Graves' disease with varied activity of thyrotropin receptor antibodies

We describe a 75-year-old man who had had a lump in his neck for about 15 years. At his first visit to our hospital, poorly differentiated papillary carcinoma of the thyroid was diagnosed by means of aspiration cytology; x-rays revealed the presence of lung metastases. He was thyrotoxic with positive thyroid stimulating antibody (TSAb). He was reluctant to undergo surgery. In an early stage of the treatment for Graves' disease, he became hypothyroid with decreased TSAb activity and strongly positive thyroid stimulation blocking antibody (TSBAb), and rapid growth of the thyroid carcinoma with anaplastic transformation was observed. The increase in the size of the transformed thyroid carcinoma was shown to be exponential by ultrasonography. This is a rare case in which anaplastic transformation of the thyroid papillary carcinoma became apparent during treatment of Graves' disease with varied activity of thyrotropin receptor antibodies.

Management options for solitary thyroid nodules in an endemic goitrous area

An analysis of management of 546 cases of solitary thyroid nodules in an endemic area is presented. None of the evaluating procedures could effectively isolate benign from malignant disease. Of 508 cases considered clinically to be benign, 42 harboured malignancy on histological examination whereas of the 38 cases suspected clinically to be malignant, 21 were histologically benign. 131I-Thyroid scanning also lacked sensitivity in identifying malignant nodules since the prevalence of malignancy in cases which were 'cold' (44/316) was not significantly different from that amongst the 'uniform' cases (15/142). Fine-needle aspiration cytology, although the most sensitive and specific evaluating modality, did not decrease the number of operations for solitary thyroid nodules nor did it increase the incidence of malignancy amongst the operated cases, because of its limitations in differentiating benign from malignant follicular neoplasms. The conditions under which surgery was advocated are described.

Thyroid-stimulating hormone promotes the secretion of vascular endothelial growth factor in thyroid cancer cell lines

BACKGROUND

Vascular endothelial growth factor (VEGF) is a vascular endothelial cell-specific mitogen secreted by some cancer cells and is a major regulator of angiogenesis. Because thyroid-stimulating hormone (TSH) promotes growth and progression of thyroid cancers, we postulated that TSH may increase the production and secretion of VEGF by thyroid cancer cells.

METHODS

We examined primary cultures of normal human thyroid (NT 1.0), medullary thyroid cancer (MTC 1.1), and cell lines derived from the papillary (TPC-1), follicular (FTC-133), and Hürthle cell (XTC-1) thyroid cancer. We quantified the concentration of VEGF in conditioned medium by means of enzyme-linked immunosorbent assay.

RESULTS

Cell lines derived from thyroid secrete VEGF. Basal VEGF secretion was similar in normal and thyroid cancer cells, except XTC-1, which has high basal secretion (p < 0.01). All thyroid cancer cells secrete significantly more VEGF than normal thyroid cells after TSH (10 mIU/ml) stimulation (p < 0.05). TSH stimulated secretion of VEGF in FTC-133 (8.2 ng/dl versus 18.8 ng/dl), TPC-1 (5.5 ng/dl versus 26.9 ng/dl), and MTC 1.1 (5.9 ng/dl versus 13.4 ng/dl) cell lines (p < 0.01), but not in NT 1.0 (8.4 ng/dl versus 9.9 ng/dl) and XTC-1 (25.4 ng/dl versus 31.2 ng/dl) cells.

CONCLUSIONS

These results suggest that VEGF secretion is constitutively activated in some thyroid cancers and that VEGF secretion is stimulated by TSH; thus TSH may promote growth in some thyroid cancers by stimulating VEGF secretion and angiogenesis.

Decreased growth rate and tumour formation of human anaplastic thyroid carcinoma cells transfected with a human thyrotropin receptor cDNA in NMRI nude mice treated with propylthiouracil

The effect of the human TSH-receptor (TSHR) on the growth of human anaplastic thyroid carcinoma cells lacking the endogenous expression of TSHR, was studied both in vitro and in vivo in NMRI nude mice. Cells from a human anaplastic thyroid carcinoma cell line (C643) were transfected with a TSHR cDNA, and clones were isolated after neomycin selection. The expression of a functional receptor protein was ensured by analysis of the specific binding of 125I-TSH and measurement of TSH-induced cAMP. Incorporation of [3H]thymidine and increase in cell number was slightly inhibited by TSH in TSHR-expressing cells in vitro. In order to investigate whether the regained expression of a functional TSHR protein in C643 cells could influence the in vivo growth, cells were injected subcutaneously into NMRI nude mice. To manipulate the endogenous level of TSH, animals were given 6n-propyl-2-thiouracil (PTU; resulting in a high TSH level), T4 (a low TSH level) or no treatment (as a control). There seemed to be a TSH induced inhibition of tumour growth, since tumours in mice treated with PTU grew after a longer take rate and with a slower growth rate. The present results suggest a TSH-mediated growth inhibition in the TSHR-transfected C 643 anaplastic thyroid carcinoma cells.

Endocrine Treatment of Cancer

Cancer has been treated by hormonal manipulation for over 100 years. Although therapeutic progress during this period has resulted mainly from clinical observation, more rational treatment approaches are now emerging from insights into the molecular basis of hormone-responsiveness. Among these are the recognition that hormonal signalling effects are transduced via specific receptor proteins, and the possibility that tumour lysis by hormonal therapies is effected by triggering of a programmed cell death pathway. Clinical progress has already been achieved through basic advances: receptor assays, for example, now permit prediction of treatment benefit in various settings. However, much remains to be learned about the mechanism and application of hormonal anticancer treatments.

Surgical considerations and approach to thyroid cancer

Patients with thyroid cancer can be safely treated by an experienced endocrine surgeon. More extensive initial surgery such as total or near-total thyroidectomy seems to decrease tumor recurrence and prolong life. When such operations can be done with minimal complications, we believe it is the treatment of choice because even low-risk patients have a 4% or 5% risk of eventually dying of thyroid cancer. If this risk of death from thyroid cancer can be decreased to 1% or 2% and the rate of serious complications is 1% or 2%, the authors believe total thyroidectomy is indicated. Most patients can be discharged within 1 day of total thyroidectomy.

Thyroid cancer management

OBJECTIVE

Thyroid cancer is the commonest endocrine malignancy, yet management remains controversial. Many endocrinologists advocate diagnosis by fine needle aspiration (FNA), treatment by thyroidectomy, ablative radioiodine (131I) and TSH suppression, together with follow-up with 131I scans or thyroglobulin (Tg) measurements. 131I (therapy or diagnosis) is given only when TSH is > 30 mIU/I. With this strategy in mind, the aim of the present study was to audit existing clinical practice in a large Edinburgh teaching hospital to establish whether a need existed for local guidelines for the management of thyroid cancer.

DESIGN AND PATIENTS

Retrospective case-note audit of 46 patients, aged 55 (range 26-86) years, admitted between 1988 and 1993 with a diagnosis of thyroid cancer.

DIAGNOSIS

Our FNA false negative rate was high (13%), aspiration technique varied considerably, and cytological reporting was not standardized.

TREATMENT

Three (11%) patients received 131I despite suboptimal TSH levels because of poorly developed mechanisms to prevent this, and 7 (25%) patients had inadequate suppression of TSH as a result of poor interspecialty communication.

FOLLOW-UP

Three (11%) patients were scanned despite TSH levels < 30 mIU/I, and in 5 (18%) Tg checks were incomplete.

CONCLUSIONS

This audit identifies several shortcomings from what might be considered optimum management of thyroid cancer; practice was far from uniform even among the endocrinologists within a single hospital and interdisciplinary communication was poor. A locally agreed and implemented protocol should address most of these problems and improve the care of thyroid cancer patients.

Thyroid growth factors, signal transduction pathways, and oncogenes

Growth of thyroid cancer cells is stimulated by various growth factors via signal transduction pathways. TSH, EGF, IGF, and TGF-alpha stimulate and TGF-beta inhibits thyroid cell growth. TSH stimulates thyroid cells via both the adenylate cyclase-PKA and the PLC-PKC-Ca signal transduction pathways. TSH-r, ras, gsp, ret, trk, and myc are oncogenes that are activated in some thyroid neoplasms. P53 and RB are tumor suppressor genes that are inactivated in some thyroid cancers.

Free thyroid hormones and a third-generation TSH assay in the detection of hyperthyroidism during long-term thyroxine treatment in thyroid carcinoma patients

We evaluated the value of serum-free thyroid hormone and thyrotropin (TSH) concentrations in the detection of peripheral hyperthyroidism during thyroxine suppression therapy. A total of 57 patients on a stable thyroxine dose and 70 controls participated in the study. Serum-free thyroxine (FT4), free triiodothyronine (FT3) and TSH were measured by immunoassays based on time-resolved fluorescence (Delfia). The assay for TSH was a modification of a third generation Delfia hTSH Ultra method. The patients were classified into euthyroid and hyperthyroid subgroups based on clinical signs and symptoms (Wayne index). Systolic time intervals (STI) were measured. The Wayne indices were higher among patients than controls (p < 0.0001). The STI results were similar in patients and controls. Only FT4 had the discriminatory power for classifying euthyroid and hyperthyroid patients according to discriminant analyses. The diagnostic value of FT4 was further assessed by calculating the area under the relative operating characteristic (ROC) curve. The area was 0.707 (SE 0.0918), which was significantly different from an area of 0.5, i.e. the area of a test of no value (p = 0.032). In conclusion, a high serum FT4 concentration indicates hyperthyroidism during long-term thyroxine treatment among thyroid carcinoma patients. Although the degree of TSH suppression can now be exactly monitored with new third generation TSH assays, hyperthyroidism cannot be defined using TSH concentration in thyroid carcinoma patients. Therefore, additional serum FT4 concentration assays are needed in the assessment of hyperthyroidism associated with TSH suppression therapy in thyroid carcinoma patients.

Biphasic effects of thyrotropin on invasion and growth of papillary and follicular thyroid cancer in vitro

The rationale for TSH suppression in the treatment of follicular thyroid cancer (FTC) and papillary thyroid cancer (PTC) is to inhibit tumor growth, prevent recurrent disease, and eventually prolong survival. We analyzed the effects of TSH on invasion and growth of 3 FTC cell lines from 1 patient (FTC133, primary; FTC236, lymph node; FTC238, lung metastasis) and 2 PTC cell lines (PTC-UC1, PTC-UC3). Cell growth and invasion through an 8-micron pore polycarbonate membrane coated with Matrigel were measured using the MTT assay. The dose-response to TSH was biphasic, stimulating invasion and growth of FTC and PTC at low concentrations (0.1-10 mU/mL), and inhibiting them at high concentrations (100 mU/mL). Interestingly, the metastatic FTC cell lines had higher basal invasion, but were less responsive to TSH than the primary tumor. TSH (1 mU/mL) stimulated invasion of FTC133 by 21%, FTC236 by 8%, and FTC238 by 8% (p < 0.01). At 100 mU/mL, TSH inhibited invasion of FTC133 by 21%, compared to 11% in FTC236 and 12% in FTC238. Also, TSH dose-dependently influenced proliferation of follicular thyroid cancer cells. At low concentrations it stimulated growth of FTC133 (20%) and inhibited it at high concentrations (23%; p < 0.01). Again, the amplitude of TSH effects was significantly smaller in the cell lines from metastatic tumors. TSH affected invasion and growth of PTC-UC1 and PTC-UC3 also biphasically. These results show that TSH may act as a mitogenic and antimitogenic growth factor for invasion and proliferation of well-differentiated thyroid cancer cells in vitro.

Hyperthyroidism associated with metastatic thyroid carcinoma

We report a patient with unilateral thyroid carcinoma, who developed hyperfunction of the thyroid gland during the metastatic progression of the thyroid carcinoma. Concurrently with this event, TSI increased and it is suggested that the differentiated aggressive metastatic thyroid neoplasm had initiated the autoimmune disorder leading to TSI production and thus to hyperplasia and hyperfunction of the thyroid resulting in hyperthyroidism.

Expression of the estrogen receptor in human thyroid neoplasms

The expression and quantitation of the estrogen receptor (ER) in human thyroid tumors were examined by biochemical, immunohistochemical, and reverse transcriptase-polymerase chain reaction (RT-PCR) techniques. For this study, neoplasms, adenomatous goiters and adjacent normal thyroid tissues were obtained from 35 patients which included 10 cases of papillary carcinomas, 17 cases of adenomas and 8 cases of adenomatous goiters. Regardless of the histopathological subtype, ER was detected in 19% (5/27) of the neoplastic tissues with the mean value of ER content of 5.0 +/- 1.3 fmol/mg protein and the mean Kd value of 0.38 +/- 0.28 nM. ER was also detected, but at a lower concentration (2.8 +/- 1.6 fmol/mg protein), in the surrounding normal tissues. There was no significant difference between the neoplasms and adenomatous goiters with respect to the incidence of ER positivity and ER content. Furthermore, ER-positive specimens, as determined by both biochemical and immunohistochemical techniques, also showed the expression of ER mRNA detected by RT-PCR method. These results demonstrate that both ER mRNA as well as ER protein are expressed in thyroid neoplasms. This suggests the possibility that estrogen may affect the tumorigenesis or the progression of some thyroid neoplasms.

TSH suppression by octreotide in differentiated thyroid carcinoma

OBJECTIVE

This study evaluates the addition of octreotide and L-thyroxine to shorten the period of exposure to unduly elevated TSH levels in patients with differentiated thyroid carcinoma undergoing total body scan with 131I.

DESIGN

Fourteen thyroidectomized patients were studied after total body scan and the restarting of different doses of thyroxine. After one year a second total body scan and a schedule of the same dose of thyroxine combined with octreotide were performed in each subject.

PATIENTS

Patients were divided into four groups according to the treatment: seven patients received initially 100 micrograms of L-thyroxine (Group 1) and after 1 year 100 micrograms of L-thyroxine plus 300 micrograms of octreotide/day (Group 3); the other seven received initially 150 micrograms of L-thyroxine (Group 2) and then 150 micrograms of L-thyroxine plus 300 micrograms of octreotide/day (Group 4).

MEASUREMENTS

Serum TSH, T3 and T4 were measured on the day of radioiodine administration (day 0) and after 14, 21, 30, 45, 60 and 90 days.

RESULTS

Mean basal TSH levels were elevated in all four groups ranging from 104 to 91 mU/I without significant differences. The patterns of TSH inhibition were however different in the four groups studied. TSH remained very elevated for a long time in Group 1 patients: at day 90 the TSH value was still 2.1 +/- 1.2 mU/I (mean +/- SEM). Patients in Groups 2 and 3 showed a similar pattern: TSH was suppressed in 45 days. The most rapid TSH inhibition was observed in Group 4 patients with a mean decrease of 88% in 14 days and complete suppression in 30 days.

CONCLUSIONS

TSH suppression by L-thyroxine is very slow and it can be significantly enhanced by combined octreotide administration. Combined therapy is safe and offers an alternative choice when high dosages of L-thyroxine are inappropriate or in conditions of advanced illness.

Endocrine surgical diseases of elderly patients

The causes, evaluation, and preoperative and postoperative care of primary hyperparathyroidism and thyroid nodules in the elderly patient population have been described. Primary hyperparathyroidism is easily diagnosed and is almost always curable by surgery. Elderly patients with asymptomatic disease are candidates for nonoperative, expectant management. If they become symptomatic, surgery should be performed. Postoperative care of the elderly patient who has undergone parathyroid exploration is potentially complicated by the patient's other medical problems, including cardiac and pulmonary difficulties, variable severity of symptoms of hypocalcemia, and sensitivity to medications. Thyroid nodules in the elderly may present later than in younger patients and are more likely to contain malignant tissue. Tissue diagnosis preoperatively, usually by FNA testing, is mandatory. Anaplastic thyroid carcinoma and thyroid lymphoma are both treated nonoperatively. Thyroid surgery in the elderly is usually well tolerated, although other medical conditions, as mentioned above, may complicate postoperative care. Thyroid carcinoma in the elderly carries a worse prognosis than in younger patients and should always be treated with postoperative adjuvant (radioablative) therapy. Although this does not affect survival (from the thyroid cancer), it does extend the disease-free interval. As the number of elderly patients increases, the frequency with which these disorders are encountered will also rise. It is important to realize that almost all elderly patients can both tolerate and benefit from surgical correction of these two disorders, if appropriate preoperative evaluation is coupled with excellent intraoperative and postoperative care.

Diagnosis, treatment, and outcome of follicular thyroid carcinoma

BACKGROUND

There have been numerous studies concerning the diagnosis, treatment, and prognosis of patients with papillary thyroid carcinoma, but relatively few addressing patients with follicular carcinoma.

METHODS

The authors analyzed their experience with 65 patients who underwent 96 thyroid operations for pure follicular thyroid carcinoma from 1956 to 1990.

RESULTS

The patients were 43 women and 22 men with a mean age of 45 years who were followed postoperatively for a mean of 10.4 years. Fifty-two patients (80%) were seen initially with a solitary thyroid nodule, and 24 (37%) had symptoms at presentation. Median tumor size was 2.2 cm. Fine-needle aspiration biopsy was performed in 20 patients, revealing a follicular neoplasm in 18 patients (90%) and an inadequate specimen in 2 patients. Nineteen patients received thyroid-stimulating hormone (TSH)-suppressive thyroid hormone therapy for an average of 4.5 months before surgery; tumor size remained the same in 10 patients (53%), increased in 5 (26%), and decreased in 2 (11%). At presentation, six patients had lymph node involvement, three had locally invasive tumors, and two had distant metastases. Initial operative treatment was lobectomy in 32 patients (49%), total thyroidectomy in 15 patients (23%), lobectomy plus contralateral partial or subtotal lobectomy in 11 patients (17%), and lesser procedures in 7 patients (11%). Twenty-nine patients had a completion total thyroidectomy, so that final surgical treatment consisted of total thyroidectomy in 44 patients (68%). Among 39 patients having intraoperative frozen section, only 3 (8%) were correctly diagnosed as having cancer. Permanent complications occurred during 3 of the 96 operations. Three patients (5%) have died of thyroid cancer (one with anaplastic transformation) since thyroidectomy, and two are living with distant metastatic disease.

CONCLUSIONS

Patients with follicular thyroid cancer, when first examined, usually have solitary thyroid nodules that are follicular neoplasms by aspiration cytology, and these nodules fail to regress in response to TSH-suppressive therapy. Frozen section rarely aids in management. The preferred treatment for follicular neoplasms is lobectomy followed by completion total thyroidectomy for histologically proven carcinomas larger than 1.0 cm. Total thyroidectomy allows use of thyroglobulin and radioiodine scanning to detect and treat metastatic disease. Complications of thyroidectomy were uncommon, and the mortality rate in treated patients was relatively low.

Increased phospholipase C activity in neoplastic thyroid membrane

The phospholipase C (PLC)-protein kinase C (PKC) signal transduction pathway appears to be important for cellular growth of many normal and neoplastic tissues. Because alterations in the thyroid-stimulating hormone (TSH) receptor-adenylate cyclase-protein kinase A system in some thyroid tumors do not correlate with tumor size, invasiveness, or metastatic potential, we studied the PLC activity in both normal and neoplastic thyroid tissues from 11 patients. Five of these patients had follicular adenomas and 6 had papillary carcinomas. An 8,000 x g membrane fraction and a 105,000 x g cytosol fraction were prepared from the normal and neoplastic human thyroid tissues. PLC hydrolyzes phosphatidylinositol, 4,5-diphosphate (PIP2) to diacylglycerol (DAG) and inositol 1,4,5-triphosphate (IP3). Phospholipase C activity was determined measuring the hydrolysis of [3H]-PIP2. The activity of PLC in the neoplastic thyroid tissue membrane fraction (20.91 +/- 2.28 nmol PIP2 hydrolyzed/mg protein/120 min) was higher than that in normal thyroid membrane (14.27 +/- 0.82) (p < 0.05). In contrast, PLC activity was similar in the neoplastic (16.12 +/- 0.86 nmol PIP2 hydrolyzed/mg protein/120 min) and normal (16.66 +/- 0.60) cytosol. There was no difference between PLC activity in the membrane fraction from adenomas (21.21 +/- 3.71 nmol PIP2 hydrolyzed/mg protein/120 min) when compared with thyroid carcinomas (20.67 +/- 3.14). Neoplastic thyroid membranes have greater PLC activity than that found in normal thyroid membranes from the same patients. Although PLC activity in benign and malignant thyroid membranes was similar, the increased PLC activity in thyroid neoplasms may be responsible for or contribute to the enhanced growth of some thyroid tumors.

Mutational activation of RAS and GSP oncogenes in differentiated thyroid cancer and their biological implications

Activating mutations of ras-genes (Kirsten-ras, Harvey-ras, N-ras) and genes encoding for the alpha subunit of G-proteins (Gs, Gi2, Gi3, Go, Gz) were assessed in 32 differentiated thyroid cancer (DTC) tissues from German (n = 22) and American (n = 10) patients. Gs-protein (GSP) and/or ras mutations were found in 69% of all tissues with a heterogeneous distribution pattern. An increased prevalence could be demonstrated in metastatic (8 of 9 mutation positive) when compared to localized disease (13 of 23 mutation positive) (p less than 0.001) and in patients greater than 50 years of age (16 of 18 mutation positive), when compared to younger patients (6 of 14 mutation positive) (p less than 0.001). No activating mutations were found on H-ras and K-ras genes nor on genes encoding for the alpha subunits of Gi2, Gi3, Go, and Gz. Differentiated thyroid cancer tissue from German patients revealed a higher prevalence for GSP mutations (73%) than did DTC from American patients (20%) (p less than 0.001). We demonstrated a high frequency of ras and GSP mutations in DTC and suggest that these mutations may contribute to our basic understanding of this disease and might initiate a new search for more rational and individualized therapeutic approaches in patients with DTC.

Effect of TSH in human thyroid cells: evidence for both mitogenic and antimitogenic effects

The well-known mitogenic effects of TSH observed in vivo on the thyroid are not always reproducible of human thyroid cells in vitro where conflicting results have been obtained. In order to clarify this issue, we have used primary cultures of human thyroid cells obtained from normal tissue and maintained in serum-free medium for several days. In this in vitro model we have studied the effect of TSH on growth by measuring three different parameters: [3H]-thymidine incorporation, cell counts, and DNA measurement. Monolayer cultures were plated at both low and high cell density (2 x 10(4) and 8 x 10(4) cells/25 mm well, respectively). Although at either cell density cultures were equally able to functionally respond to TSH in terms of cAMP accumulation a significant growth response to TSH was observed only in low density cultures. In high density cultures TSH had an antimitogenic effect. Moreover, TSH potentiated the mitogenic effect of insulin only in low density cultures. In contrast to TSH, FCS induced a similar proliferative response at both high and low cell density. Following TSH stimulation, cAMP content was always increased, paralleling the effect of growth in low density but not in high density cultures. The cAMP analogues dibutyryl-cAMP and 8-bromo-cAMP, as well as cholera toxin and forskolin, did not mimic the mitogenic effect of TSH but had an antiproliferative effect. In addition, these agents blunted the proliferative effect of insulin. These data suggest that in thyroid cells TSH is able to elicit both a mitogenic and an antimitogenic effect depending on the environmental conditions such as cell density.(ABSTRACT TRUNCATED AT 250 WORDS)

TRIAC (3,5,3'-triiodothyroacetic acid) has parallel effects at the pituitary and peripheral tissue levels in thyroid cancer patients treated with L-thyroxine

OBJECTIVE

To investigate whether the addition of 3,5,3'-triiodothyroacetic acid (TRIAC) to thyroxine (T4) treatment can suppress TSH secretion without inducing thyrotoxicosis at the periphery.

DESIGN

Thyroid cancer patients were studied with different treatment modalities: T4 at supraphysiologic dose (2.5 +/- 0.3 micrograms/kg/day) and after reduction to a physiologic dose (1.8 +/- 0.3 micrograms/kg/day); then with the addition of TRIAC 500 or 1000 micrograms/day to the physiologic T4 treatment dose.

PATIENTS

Twenty-two patients who had total thyroid ablation for differentiated thyroid carcinoma.

MEASUREMENTS

Clinical and biological parameters of thyroid hormone action studied included heart rate, serum creatine phosphokinase, testosterone-oestradiol binding globulin, procollagen III and osteocalcin levels.

RESULTS

The addition of TRIAC induced a significant and dose-dependent decrease in serum TSH levels and parallel effects on peripheral tissues. Compared to the suppressive T4 treatment dose, the addition of TRIAC to the physiologic T4 dose resulted in greater inhibition of TSH secretion in only 50% of the patients. The effects at the periphery of both treatment modalities were similar for a comparable level of TSH suppression.

CONCLUSIONS

Even at low dose and when combined with T4, TRIAC has parallel effects on the pituitary and peripheral tissues. There is no justification for the use of TRIAC as suppressive treatment in thyroid cancer patients.

Role of thyroid stimulating hormone suppression in the management of thyroid cancer

Well-differentiated thyroid cancers (papillary, follicular, and some Hurthle cell tumors) contain membrane receptors for TSH. Responsiveness of these tumors to TSH stimuli is documented by increased radioactive iodine uptake, secretion of thyroglobulin, increase in thyroid size, and potential progression to an anaplastic type. Although TSH suppression has a variable effect on the growth of existing tumors and the incidence of recurrent disease, there is a sound rationale for long-term TSH suppression in all patients with differentiated tumors of the thyroid. The ultrasensitive TSH test permits ready monitoring of the adequacy of thyroxine dosage. The cost is minimal (approximately $.10/day) and the risks are negligible if one assumes the avoidance of hyperthyroxinemia.

Evaluation of thyroid nodules

The first consideration in evaluating the thyroid nodule is whether it is functioning and causing hyperthyroidism. Autonomous nodules should be treated with either surgery or I-31, with surgery favored due to the possibility, although small, of malignancy. Thyroid scans are no longer recommended during the initial evaluation of the thyroid nodule. Ultrasound is useful in determining the size of the nodule and whether it is multinodular thyroid disease, but it cannot detect thyroid cancer. Fine needle aspiration biopsy is currently the procedure of choice for evaluating all thyroid nodules. For accuracy of the cytological analysis, it is important that adequate tissue samples be obtained. False negative findings are of most concern to the clinician and occur in 2-10% of reported fine needle aspiration biopsy series. Nodules thought to be benign will need continued follow-up.

Thyroid cancer

There have been important recent advances in our understanding of the biologic nature of thyroid cancer and in the early diagnosis of the disease. Despite these advances, there is still considerable controversy over the management of thyroid cancer, including the extent of surgery, the indications for the use of iodine-131, the effectiveness of thyroid-stimulating hormone suppression, and the prediction of outcome. In this review, the current status of the diagnosis and management of the various types of thyroid cancer are carefully reviewed and extensively documented.

Survival discriminants for differentiated thyroid cancer

Since 1975, the American Cancer Society, Illinois Division, has published end results of major cancer sites drawn from patient data contributed voluntarily by hospital cancer registries throughout the state. The current study was undertaken, in part, to apprehend information regarding contested areas in the management of patients having differentiated (papillary/follicular) thyroid cancer. A total of 2,282 patients with either papillary or follicular carcinoma of the thyroid from 76 different Illinois hospitals and providing 10 years of follow-up information (life-table analysis) were retrospectively analyzed for demographic, disease, and treatment-related predictors of survival. Multivariate analysis using the Cox proportional hazards method was made for stage, age, race, sex, morphology, history of radiation exposure, presence of positive lymph nodes, initial surgical treatment, postoperative iodine 131 therapy, and replacement/suppressive thyroid hormone treatment. Statistically significant (p less than or equal to 0.05) predictors of favorable survival after thyroid cancer were low stage (I and II), young age (less than 50 years), white race, female sex, and the administration, postoperatively, of either thyroid hormone or radioactive iodine. Factors that had no influence on survival were lymph node status, choice of initial surgical treatment, and a history of prior irradiation. We suggest that where a prospective clinical trial is impracticable, a retrospective analysis of a large and detailed database, such as that available from cooperating hospital-based tumor registries, may yet provide useful insights to solutions of cancer management problems.

Thyroxine suppressive therapy of benign solitary thyroid nodules: a prospective randomized study

Patients with solitary thyroid nodules that are benign on aspiration biopsy are often treated nonsurgically. To find out if thyroxine therapy is effective, 74 patients were randomized to receive levothyroxine treatment or nothing. There were 8 males and 66 females. Their mean age was 39 years. The mean nodule size was 3.6 cm and the mean nodule duration was 11 months. All patients had normal serum thyroxine and thyroid stimulating hormone (TSH) levels, and positive thyrotropin releasing hormone (TRH) tests. The dose of thyroxine was adjusted until the TRH test was negative. Patients were followed at 6-month intervals in the first 2 years and yearly thereafter, with measurement of the nodule diameter. The mean follow-up period was 1.5 years. In the 37 patients receiving thyroxine therapy, 8 had disappearance of nodules, 6 had greater than 50% reduction in nodule size. In 19, the nodules were unchanged and in 4, the nodules were enlarged. In the 37 patients receiving no drug, 8 had disappearance of nodules, 5 had greater than a 50% reduction in nodule size, 17 had nodules unchanged, and 7 had enlarged nodules (p greater than 0.9). The mean reduction in nodule diameter at various follow-up periods was greater in the thyroxine group, but the difference did not reach statistical significance. Carcinoma was found in 1 patient in each group and both of them experienced nodule enlargement. We conclude that an adequate suppressive dose of levothyroxine does not alter the natural course of benign solitary thyroid nodules. An enlargement of the nodule or a change in its consistency should be further investigated to exclude malignancy.

Solitary thyroid nodule: diagnosis and management

Thyroid nodules are common. Most are benign lesions since clinically important thyroid carcinoma is a relatively rare disease. The most sensitive and specific test for the diagnosis of thyroid cancer is fine-needle aspiration biopsy, but its diagnostic accuracy depends upon whether or not one excises all suspicious nodules, thus including them as correctly diagnosed. Nevertheless, fine-needle aspiration biopsy is the most sensitive, specific, and cost-effective test for thyroid cancer. Therapy depends upon the cause of the thyroid nodule.