Jacob Robbins

Comparison of administration of recombinant human thyrotropin with withdrawal of thyroid hormone for radioactive iodine scanning in patients with thyroid carcinoma.

BACKGROUND To detect recurrent disease in patients who have had differentiated thyroid cancer, periodic withdrawal of thyroid hormone therapy may be required to raise serum thyrotropin concentrations to stimulate thyroid tissue so that radioiodine (iodine-131) scanning can be performed. However, withdrawal of thyroid hormone therapy causes hypothyroidism. Administration of recombinant human thyrotropin stimulates thyroid tissue without requiring the discontinuation of thyroid hormone therapy. METHODS One hundred twenty-seven patients with thyroid cancer underwent whole-body radioiodine scanning by two techniques: first after receiving two doses of thyrotropin while thyroid hormone therapy was continued, and second after the withdrawal of thyroid hormone therapy. The scans were evaluated by reviewers unaware of the conditions of scanning. The serum thyroglobulin concentrations and the prevalence of symptoms of hypothyroidism and mood disorders were also determined. RESULTS Sixty-two of the 127 patients had positive whole-body radioiodine scans by one or both techniques. The scans obtained after stimulation with thyrotropin were equivalent to the scans obtained after withdrawal of thyroid hormone in 41 of these patients (66 percent), superior in 3 (5 percent), and inferior in 18 (29 percent). When the 65 patients with concordant negative scans were included, the two scans were equivalent in 106 patients (83 percent). Eight patients (13 percent of those with at least one positive scan) were treated with radioiodine on the basis of superior scans done after withdrawal of thyroid hormone. Serum thyroglobulin concentrations increased in 15 of 35 tested patients: 14 after withdrawal of thyroid hormone and 13 after administration of thyrotropin. Patients had more symptoms of hypothyroidism (P<0.001) and dysphoric mood states (P<0.001) after withdrawal of thyroid hormone than after administration of thyrotropin. CONCLUSIONS Thyrotropin stimulates radioiodine uptake for scanning in patients with thyroid cancer, but the sensitivity of scanning after the administration of thyrotropin is less than that after the withdrawal of thyroid hormone. Thyrotropin scanning is associated with fewer symptoms and dysphoric mood states.

Thyroid Cancer: A Lethal Endocrine Neoplasm

This conference focuses on the controversies about managing thyroid cancer, emphasizing the possibility that the treatment of patients with potentially fatal thyroid cancer may be improved. Although the mortality rate from thyroid cancer is low, it is the highest among cancers affecting the endocrine glands (excluding the ovary). Exposure to radiation during childhood in the 1930s and 1940s increased the incidence of but not the mortality from thyroid cancer, because these tumors are mainly papillary cancers developing in young adults. These rates may change as the exposed cohort ages. Risk factors that increase mortality include older patient age and the growth characteristics of the tumor at diagnosis, the presence of distant metastases, and cell type (for example, the tall-cell variants of papillary cancer, follicular cancer [to be distinguished from the more benign follicular variant of papillary cancer], medullary cancer, and anaplastic cancer). Local metastases in lymph nodes do not seem to increase the risk for death from papillary cancer, but they do increase the risk for death from follicular and medullary cancer. In the latter, mortality is decreased by the early detection and treatment of patients with the familial multiple endocrine neoplasia syndrome 2a. There are excellent tumor markers for differentiated cancer of the parafollicular and of the follicular cells (serum calcitonin and serum thyroglobulin levels, respectively). Measuring the calcitonin level allows early diagnosis of familial medullary cancer, whereas measuring the thyroglobulin level, although useful only after total thyroidectomy, allows early recognition of recurrence or metastases of papillary or follicular cancer. Initial surgery, protocols for follow-up, and the use of radioiodine for the ablation of any residual thyroid and the treatment of metastatic cancer are discussed. Because these tumors resist currently available chemotherapy regimens, possible ways to increase the effectiveness of radioiodine therapy are considered as are new approaches to treatment.

Outcome after Treatment of High-Risk Papillary and Non-Hurthle-Cell Follicular Thyroid Carcinoma

The treatment of thyroid cancer has been investigated extensively, but disagreement remains about the degree of aggressiveness needed in its management. Despite the general perception that the prognosis is excellent, 9% of patients with thyroid cancer die of the disease [1]. Patients with the less differentiated types of thyroid cancer or those presenting at a more advanced stage face higher mortality rates [2, 3]. In addition, the recurrence rate after surgery is more than 20% in persons with differentiated thyroid cancer [2]. Therefore, the ability to define the most effective therapeutic interventions on the basis of patient stratification by histologic type and stage of cancer at initial presentation should improve survival and decrease recurrence rates. The initial treatment for thyroid cancer is surgery, but the extent of surgery needed to improve outcome remains controversial [4-6]. Some studies have shown that more extensive thyroid resection reduces the recurrence rate but has a less definite effect on survival [2, 7]. More extensive surgery may be associated with a higher prevalence of complications, usually hypoparathyroidism or recurrent laryngeal nerve damage (or both), in 3% to 15% of patients [8-10]. The indications for postoperative ablative radioiodine therapy and the required administered activity are also under debate. Multifocality and lymph node involvement at presentation in 46% of persons with papillary thyroid cancer (of whom 25% face persistent or recurrent disease) argue in favor of this therapy [2, 11, 12], despite the risk for sialoadenitis, gastrointestinal symptoms, occasional bone marrow suppression, and possible second cancers [13]. The role of external radiation in the treatment of differentiated thyroid cancer is also highly controversial. Increased recurrence [14], no therapeutic benefit [15-17], and improved local control [18, 19] have all been reported. The National Thyroid Cancer Treatment Cooperative Study Registry was established in 1986 to define clinical practice and to address the effectiveness of therapies on morbidity and mortality by prospectively enrolling a large population of patients from multiple institutions. Patients have been stratified by uniform criteria and followed prospectively from the time of initial diagnosis and treatment. This 9-year report from the registry describes outcomes in patients with high-risk, differentiated thyroid cancer, a group of patients expected to have substantial morbidity and mortality in this time period. Methods A total of 1607 patients in whom thyroid cancer was diagnosed on or after 1 January 1987 were prospectively enrolled in the registry by the 14 participating institutions. No more than 20% of cases came from any single institution or city. Data forwarded to the registry were coded, and individual identifiers, such as name and Social Security number, were kept confidentially by the principal investigator at each institution. Because the patients therapy was not altered by participation in the registry, requirements for informed consent were determined by the institutional review boards at each participating institution, and their mandates were followed. Age, sex, ethnic background, histologic diagnosis, size of primary tumor, multifocality, local invasiveness, and regional or distant metastases were documented. The histologic diagnosis was established at each institution. All variants of papillary cancer, including so-called mixed papillary and follicular carcinomas, were included in the papillary group. Analyses for papillary carcinomas that included and excluded the more aggressive tall-cell variant were performed. The Hurthle cell (oxyphilic) variant of follicular carcinoma was excluded from the follicular group. Patients were stratified on the basis of pathologic diagnosis, age, tumor size, local invasiveness, and extent of metastases at the time of first surgical intervention as determined by gross and histologic findings at surgery, whole-body radioiodine scans, chest radiographs, and other radiologic studies. This stratification system was established empirically before initiation of the registry by a group of experienced clinicians on the basis of information available in 1985. The criteria for categorization as high risk are noted in Table 1. Patients with preoperative vocal cord paresis or with postoperative hypocalcemia or vocal cord paresis that persisted 2 months or less were not designated as having these complications of surgery. The extent of initial surgery, use of postoperative radioiodine therapy, and application of external radiation therapy were analyzed for impact on outcome. With rare exceptions, all patients received thyroxine therapy. Table 1. Criteria for Stratification to High-Risk Groups Outcomes were death due to thyroid cancer or to complications of its treatment, progression (defined as a patient alive with progressive thyroid cancer or dead because of thyroid cancer or complications of its treatment at last follow-up), and disease-free survival (defined as a patient alive with no known residual thyroid cancer or free of thyroid cancer at the time of death from other causes). Statistical Analysis All data were extracted by using a computer-based integrated data management package (Med-log, Information Analysis Corporation, Incline Village, Nevada). Cox proportional-hazards models were performed to determine whether each predictor variable was associated on univariate analysis (Table 2) with survival, progression, and disease-free survival (SAS Institute, Cary, North Carolina). The hazard model was also used to identify the set of predictor variables that best explained the probabilities of overall survival, cancer-specific mortality, progression of disease, or disease-free survival (Table 3). A P value of 0.05 or less was considered statistically significant. Risk ratios obtained from the Cox proportional-hazards analyses are given with 95% CIs. Risk ratios less than 1 indicate improved outcome, and those greater than 1 indicate a worsened outcome. Table 2. Variables Associated with Mortality, Progression, and Disease-Free Survival (by Univariate Analysis) Table 3. Variables That Best Predict Overall Mortality, Cancer-Specific Mortality, Progression of Disease, or Disease-Free Survival (by Multivariate Analysis) Results Follow-up Three hundred three patients with papillary carcinoma and 82 patients with follicular carcinoma were considered to have high-risk thyroid cancer. Twenty patients (5.2%) were lost to follow-up. An additional 64 patients were not included in the survival analyses because no information on patient status was available (n = 60), no cause of death was recorded (n = 2), or patients were alive with no cancer status reported (n = 2). Demographic characteristics of the two groups were similar regardless of whether these cases were included. Patients were followed for a mean of 3.1 years after the date of surgery; 35% were men. The mean (SD) age at entry was 57 15 years. Sex and Age Compared with men, women with papillary cancer had a lower risk for overall mortality (risk ratio [RR], 0.03 [95% CI, 0.23 to 0.92]) but not cancer-specific mortality. Older age did not affect outcome in patients with papillary carcinoma or those with follicular carcinoma, but an age effect might be masked by the fact that age was a factor in defining these high-risk patients. Histologic Type Only 18 patients with papillary cancer had the tall-cell variant (P not significant by multivariate analysis). By univariate analysis, radioiodine therapy was associated with reduced disease progression (risk ratio, 0.10 [CI, 0.01 to 0.72]; P = 0.02). Thyroid Surgery The first surgical procedure on the thyroid and any surgical therapy of the thyroid that occurred within the next 4 months were classified as initial thyroid surgery. Data were not sufficient to allow analysis of the effect of modified neck dissections on complication rates. Of 300 patients with papillary cancer, 256 (85.3%) had a total or near-total thyroidectomy as initial thyroid surgery, 10 (3.3%) had bilateral subtotal thyroidectomy, 26 (8.7%) had lobectomy, 1 (0.3%) had lumpectomy, 4 (1.3%) had biopsy only, and 3 (1.0%) had nonspecified surgery. Of 80 patients with follicular cancer, 57 (71.3%) had total or near-total thyroidectomy as initial thyroid surgery, 2 (2.5%) had bilateral subtotal thyroidectomy, 13 (16.3%) had lobectomy, 4 (5.0%) had lumpectomy, and 4 (5.0%) had biopsy only. The charts of all patients with reported surgical complications were reviewed. The complication rate of initial surgery varied among centers. The overall rate of some type of complication was 14.4% (52 of 360 patients). Specific data on complications were available for 286 of 303 patients with papillary cancer and 74 of 82 patients with follicular thyroid cancer. Hypoparathyroidism alone occurred in 19 of 286 (6.6%) patients with papillary cancer and 3 of 74 (4.0%) patients with follicular cancer. Vocal cord palsy alone was noted in 17 of 286 (5.9%) patients with papillary cancer and 6 of 74 (8.0%) patients with follicular cancer. Combined hypoparathyroidism and vocal cord palsy occurred in 4 of 286 (1.4%) patients with papillary cancer and no patients with follicular cancer. Data were not sufficient to allow analysis of any effect of modified neck dissections on complication rates. Overall mortality from papillary cancer improved with total or near-total thyroidectomy compared with other surgical procedures (RR, 0.41 [CI, 0.20 to 0.85]) (Table 2). Progression of disease and disease-free survival were not improved by more extensive surgery, and surgery did not affect mortality, progression, or disease-free survival in patients with follicular cancer by univariate (Table 2) or multivariate (Table 3) analyses. Radioiodine Therapy Postoperative radioiodine therapy with iodine-131 was administered to 258 of 302 (85.4%) patients with papillary cancer; the init

Chernobyl-related thyroid cancer in children of Belarus: a case-control study.

The accident at the Chernobyl nuclear power plant on April 26, 1986, released approximately 2 EBq of 131I and other radioiodine isotopes that heavily contaminated southern Belarus. An increase in thyroid cancer reported in 1992 and attributed to the Chernobyl accident was challenged as possibly the result of intensive screening. We began a case-control study to test the hypothesis that the Chernobyl accident caused the increase in thyroid cancer. Records of childhood thyroid cancer in the national therapy centers in Minsk in 1992 yielded 107 individuals with confirmed pathology diagnoses and available for interview. Pathways to diagnosis were (1) routine endocrinological screening in 63, (2) presentation with enlarged or nodular thyroid in 25 and (3) an incidental finding in 19. Two sets of controls were chosen, one matched on pathway to diagnosis, the other representing the area of heavy fallout, both matched on age, sex and rural/urban residence in 1986. The 131I dose to the thyroid was estimated from ground deposition of 137Cs, ground deposition of 131I, a data bank of 1986 thyroid radiation measurements, questionnaires and interviews. Highly significant differences were observed between cases and controls (both sets) with respect to dose. The differences persisted within pathway to diagnosis, gender, age and year of diagnosis, and level of iodine in the soil, and were most marked in the southern portion of the Gomel region. The case-control comparisons indicate a strong relationship between thyroid cancer and estimated radiation dose from the Chernobyl accident.

Recurrence after treatment of micropapillary thyroid cancer.

BACKGROUND Despite very low mortality associated with micropapillary thyroid cancer, locoregional recurrence is common and controversy exists regarding optimal surgical treatment and the role of adjunctive radioiodine. METHODS The National Thyroid Cancer Treatment Cooperative Study Group Registry was analyzed for recurrences in patients with unifocal versus multifocal micropapillary cancer, with or without nodal disease, depending upon the extent of surgery and the use of adjunctive radioiodine. Six hundred eleven patients considered disease-free after initial therapy were followed for 2572 person-years. RESULTS Thirty patients (6.2%) had recurrences detected at a mean 2.8 years after primary treatment. Recurrences did not differ between patients with unifocal and multifocal disease overall; however, among patients who received less than a near-total thyroidectomy (NTT), those with multifocal disease had more recurrences than those with unifocal disease (18% vs. 4%, p = 0.01). Patients with multifocal disease who had a total (T) or NTT trended toward fewer recurrences than those undergoing less than an NTT (6% vs. 18%, p = 0.058). In patients who did not receive radioiodine therapy, recurrence was more common in patients with multifocal disease versus unifocal disease (7% vs. 2%, p = 0.02). However, radioiodine did not reduce recurrences in patients with multifocal disease or patients with positive nodes. Patients with positive nodes had more recurrences than node-negative patients regardless of surgical extent or use of radioiodine. CONCLUSIONS Patients with micropapillary multifocal disease have a reduced risk of recurrence after a T/NTT compared with less surgery. A randomized, controlled trial is necessary and feasible to determine if radioiodine ablation of thyroid remnants is advantageous in patients with intrathyroidal micropapillary cancer.

Antithyroid effects of lithium

Lithium has been reported to be goitrogenic when used for the treatment of manic-depressive psychosis. To investigate the effects of lithium on iodine metabolism, male Sprague-Dawley rats were placed on a low iodine (LID) or normal iodine diet (NID) containing enough Li(2)CO(3) to give serum lithium levels of 0.23-0.86 mEq/liter (human therapeutic range is 0.6-1.6 mEq/liter). The following effects were noted with lithium treatment: (a) thyroid weight increased concomitant with a slowing of thyroidal iodine release; (b) the ability to concentrate iodide was increased only after goiters were established; (c) on the LID, (131)I uptake was elevated throughout all phases of treatment, even when the release rate was normal; (d) iodine organification was unaffected but the proportion of (131)I present as iodothyronines was decreased; (e) the thyroidal (127)I content was increased; (f) despite these changes, the serum PBI remained normal as did the thyroxine turnover rate; and (g) thyrotropin (TSH) levels in serum were the same as controls except for a slight elevation early in the course of treatment; TSH levels did not correlate with goitrogenesis. When LiCl was injected in large doses into intact rats (giving serum lithium levels of 3.08-3.89 mEq/liter), the iodide concentrating mechanism, (131)I uptake, and (131)I release rates were depressed. Similar experiments in hypophysectomized rats receiving TSH demonstrated these to be local antithyroid effects not mediated through the pituitary. The discrepancy between acute and chronic responses to lithium, and the dissociation between the inhibition of iodine release and stimulatory effects is discussed.

The Use of Lithium in the Treatment of Thyrotoxicosis

Since lithium has been shown to inhibit release of iodine from the thyroid, we have investigated its therapeutic potential in thyrotoxicosis. Eight detailed (131)I kinetic studies were performed on seven thyrotoxic women and data was analyzed using a computer program. Lithium at serum levels of about 1 mEq liter decreased the loss of (131)I from the thyroid, led to a fall in serum (131)I levels and diminished urinary (131)I excretion. Computer simulation of the lithium effect required, in every case, that lithium inhibit hormonal and nonhormonal thyroid iodine release. In five cases a second lithium effect was required for a satisfactory fit of the model soluton with observed data: namely, an inhibition of hormone disappearance from serum. NEITHER INHIBITION OF RELEASE NOR OF HORMONE DISAPPEARANCE SEEMED TO BE AFFECTED BY METHIMAZOLE (RELEASE: 52% decrease without methimazole, 60% with methimazole; hormone disappearance: approximately 60% decrease in both). When Li(+) was discontinued, recovery of the iodine release rate and hormone disappearance rate over the observed time span was variable, ranging from no recovery to rates that exceeded pre-Li(+) values. When Li(+) is used alone its effect on serum hormone levels is diminished due to continued accumulation of iodide by the thyroid. Thus, serum thyroxine-iodine levels fell 21-30% in 6-8 days in patients who did not receive methimazole and 15-67% in the methimazole-treated subjects. For prolonged therapy, therefore, a thiocarbamide drug must be used in conjunction with Li(+). The similarity of inhibition of iodine release from the thyroid produced by Li(+) and iodides is discussed.

Fine-needle aspiration cytology in the preoperative diagnosis of thyroid nodules.

Fifty consecutive patients were studied to assess the utility of fine-needle aspiration cytology for the diagnosis of hypofunctioning thyroid nodules. In two patients, cysts were evacuated and did not recur. Thirty-three patients underwent excisional biopsy; the aspiration biopsy result was not a criterion for surgery. Satisfactory aspiration specimens were obtained in 32 patients (97%). The diagnosis in nine aspiration specimens was malignant; of these seven (78%) were correct and there was one false-positive and one occult carcinoma unrelated to the clinically detected nodule. Five aspirations showed suspected malignancy; of these, two were carcinoma, one was an occult carcinoma, and two were benign. Eighteen aspirations were interpreted as benign; of these, 17 (94%) were correct and the one false-negative diagnosis was a well-differentiated follicular carcinoma. The procedure is useful in assessing the need for surgery in high-risk patients and in selecting patients for thyroid-suppression therapy.

Iodine and the brain

Though the means of preventing iodine-deficiency disorders is obvious, the mechanisms are of great interest to developmental neurologists and psychologists. In particular, endemic cretinism is virtually unseen and so unstudied in the West, but the considerable research done by the Chinese is now bei

Thyroxine Transport Proteins of Plasma. Molecular Properties and Biosynthesis

Publisher Summary This chapter discusses the molecular properties and biosynthesis of the thyroxine transport proteins of plasma. The purification of the complete amino acid sequence and the high-resolution X-ray diffraction model of pre-albumin (PA) have helped enhance the knowledge of the physiology of these proteins. Apart from thyroxine-binding globulin and PA, several other serum proteins interact with the thyroid hormones. However, both human and bovine serum albumin, in addition to several less active sites, possess one binding site for thyroxine with a rather high affinity constant. Despite its abundance in plasma, albumin transports only about 10% of the circulating thyroid hormone. Other proteins interacting with thyroxine include lipoproteins. In severe illnesses and in acute stress, the disappearance rate of PA from plasma is usually normal, which suggests that the low serum PA level in the patients is the result of a low rate of synthesis.