Repeated 131I treatment of a residual ovarian teratoma containing malignant thyroid tissue

A 49-year-old woman with ovarian teratoma received 131I treatment three times for an unresectable mass containing malignant thyroid tissue after surgery. Repeated 131I treatment effectively reduced serum thyroglobulin (Tg) level and tumour uptake of 131I, despite absence of any change in size of the treated tumour. Treatment did not inhibit the increase of serum CA-125 and tumour 201Tl uptake, associated with progression of a radioresistant intratumoral hyper-perfused tissue component, detected by colour Doppler ultrasound. Serum CA-125 level and tumour 201Tl uptake were not significantly changed despite temporary increases in serum Tg level after each 131I treatment. These observations indicate the importance of diagnostic measures using combined functional imaging and tumour markers in managing this rare tumour.     

Effect of 131I therapy on serum calcitonin levels in patients with Graves' disease

In a group of patients suffering from Graves' disease a transitory fall of serum calcitonin levels and an increase of triiodothyronine concentrations could be detected after 131I therapy. The transient decrease of the calcitonin values might be related to the high radiosensitivity of the parafollicular cells and to a consecutive impairment of calcitonin production, while the rise of triiodothyronine secretion could be explained by the radiation-induced destruction of the thyroid gland. The drop of serum calcitonin levels lasted for a short period only and did not affect serum Ca concentrations, thus the assumption is highly improbable that the temporarily altered calcitonin secretion involves late consequences for the skeletal system after 131I therapy.     

Tumour dosimetry and response in patients with metastatic differentiated thyroid cancer using recombinant human thyrotropin before radioiodine therapy

The development of recombinant human thyrotropin (rhTSH) has given clinicians new options for diagnostic follow-up and treatment of patients with differentiated thyroid cancer (DTC). This paper evaluates the tumour dosimetry and response following -iodine-131 treatment of metastatic thyroid cancer patients after rhTSH stimulation instead of classical hormone withdrawal-induced hypothyroidism. Nineteen consecutive (131)I treatments in 16 patients were performed after rhTSH stimulation. All patients had undergone a near-total thyroidectomy followed by an ablative dosage of (131)I. They all suffered from metastatic or recurrent disease showing tumoral (131)I uptake on previous post-treatment scintigraphy. Dosimetric calculations were performed using (131)I tumour uptake measurements from post-treatment (131)I scintigrams and tumour volume estimations from radiological images. Response was assessed by comparing pre-treatment serum thyroglobulin (Tg) level with the Tg level 3 months post treatment. In 18 out of 19 treatments, uptake of (131)I in metastatic or recurrent lesions was seen. The median tumour radiation dose was 26.3 Gy (range 1.3-368 Gy), and the median effective half-life was 2.7 days (range 0.5-6.5 days). Eleven of 19 treatments (10/16 patients) were evaluable for response after 3 months. (131)I therapy with rhTSH resulted in a biochemical partial response in 3/11 or 27% of treatments (two patients), biochemical stable disease in 2/11 or 18% of treatments and biochemical progressive disease in 6/11 or 55% of treatments. Our study showed that although tumour doses in DTC patients treated with (131)I after rhTSH were highly variable, 45% of treatments led to disease stabilisation or partial remission when using rhTSH in conjunction with (131)I therapy, without serious side-effects and with minimal impact on quality of life. RhTSH is therefore adequately satisfactory as an adjuvant tool in therapeutic settings and is especially suitable in advanced recurrent or metastatic DTC patients who may be intolerant to TSH stimulation by levothyroxine withdrawal.     

Role of thallium-201 total-body scintigraphy in follow-up of thyroid carcinoma

To evaluate the reliability of total-body scintigraphy using [201Tl]chloride in postoperative follow-up of thyroid carcinoma, this procedure was performed in 326 patients after total thyroidectomy for thyroid carcinoma. The results were compared with those of 131I scintigraphy and thyroglobulin assays. 201Tl total-body scintigraphy was found to have the greatest sensitivity (94%), whereas 131I scintigraphy had the highest specificity (99%). It is shown that 201Tl total-body scintigraphy is a useful procedure in follow-up of thyroid cancer, however, the combination of parameters provides the greatest reliability. In medullary thyroid carcinoma, which is usually 131I negative, 201Tl total-body scintigraphy can be of great value for the localization of metastases which are indicated by elevated serum levels of calcitonin and carcinoembryonic antigen.     

Results of radioiodine therapy in 47 patients with distant metastases of differentiated thyroid carcinoma

In the last ten years, 47 patients with distant metastases of differentiated thyroid carcinoma have been treated with 131I following total thyroidectomy. Post-therapy whole body 131I scans revealed detectable uptake in the metastatic lesions in 23 (62%) of 37 patients with lung metastases, 10 (67%) of 15 patients with bone metastases five (71%) of seven patients with mediastinal metastases, and neither of two patients with brain metastases. The concentration of 131I in the metastases was significantly correlated with serum T3 and T4 concentrations, and inversely correlated with serum TSH concentrations. Most of the patients with a strong positive scan were euthyroid, suggesting that thyroid hormones produced by the tumor compensated for hypothyroidism following total thyroidectomy. There was no significant relationship between serum thyroglobulin concentration during T4 replacement therapy and 131I uptake or the efficacy of therapy. Twenty patients with lung (54%), five with bone (33%), two with mediastinal (29%), and none with brain metastases showed tumor regression after treatment. Significantly increased 131I uptake in lung metastases, better therapeutic results and better prognosis were demonstrated in young patients. In conclusion, age, 131I whole body scanning and serum thyroid hormone concentrations are considered to be useful in predicting the efficacy of 131I treatment for distant metastases, especially in the lung.     

Sensitivity of 123I whole-body scan and thyroglobulin in the detection of metastases or recurrent differentiated thyroid cancer

Primary treatment of differentiated thyroid carcinoma consists of total thyroidectomy followed by ablation of thyroid tissue remnants and possible metastases by means of radioactive iodine. After complete destruction of remnants, metastases or recurrence can be detected by measurement of the serum thyroglobulin level as well as by radionuclide methods. Here we report on the sensitivity of diagnostic 123I scintigraphy and serum thyroglobulin measurement for tumour detection in patients with proven recurrence or metastases. Fifty-five patients who received their first high activity (1,850-5,550 MBq) of 123I therapy after total thyroidectomy and 131I ablation were included in the study. The thyroglobulin level was measured both during TSH-suppressive L-thyroxine therapy (Tg-on) and 4-6 weeks after L-thyroxine withdrawal (Tg-off, TSH>20 mU/l). Prior to treatment, whole-body scanning (WBS) was performed 24 h after the administration of 111-370 MBq 123I. The therapeutic activity of 1,850-5,550 MBq 131I was administered within 24 h after diagnostic scanning. The mean interval between 131I therapy and post-therapeutic WBS was 8.6 days (range 3-15 days). The sensitivity of WBS, Tg-on and Tg-off was 75%, 82% and 98%, respectively. The overall sensitivity of the combination of Tg-on with WBS and of Tg-off with WBS was 95% and 100%, respectively. In 12 out of 51 cases either Tg-off or Tg-on or both Tg-on and Tg-off levels were elevated while 123I-WBS was negative. More lesions were visible on the post-therapeutic 131I scan than on the corresponding diagnostic 123I scan (n=13). Tg values increased significantly (P<0.0001) after thyroid hormone withdrawal. Early treatment of distant metastases or tumour remnants of differentiated thyroid carcinoma is favoured and 131I treatment should also be considered in patients with a negative WBS but positive serum Tg level. The finding of a positive Tg-off level, which is clearly above the corresponding Tg-on value, is sufficient to make this decision. Additional diagnostic 123I WBS will not improve sensitivity.     

Radiation protection issues of treating hyperthyroidism with 131 I in patients on haemodialysis

We report on the cases of two patients referred for 131I treatment of hyperthyroidism who were dependent on haemodialysis. Following 131I administration, all disposable lines and filters from dialysis were collected and measured for 131I radioactivity. The amount of 131I retained by the filters at the end of each successive dialysis session was found to decay with effective half-lives of 6.6+/-0.2 and 6.3+/-0.2 days. Dose rate measurements at 1m from the patients were recorded to find the effective half-life of the radioiodine clearance, which were found to be 6.9 and 7.1 days. From measured dose rates taken at 30 cm, the radiation hazard to ward staff involved in patient management was shown to be negligible.     

Gonadal function in patients with differentiated thyroid cancer treated with (131)I

The aim of this study was to evaluate the effect of treatment with radioactive iodine ((131)I) on gonadal function in males and females with follicular or papillary thyroid carcinoma. Consenting patients at reproductive age were grouped according to the cumulative dose of (131)I received and followed-up for at least 12 months. Overall, 246 patients (159 females, 87 males) were studied. In all males, serum levels of follicle-stimulating hormone (FSH), luteinising hormone (LH), and testosterone were measured before radioiodine treatment and 2, 6 and 12 months afterwards; fifty-three of all patients underwent semen analysis also. On females, tests for serum levels of LH, FSH, estrogen, and progesterone were performed. In 87.4% of males, there was an increase in serum FSH level after (131)I treatment and in 20.7% of them this level remained high during the follow-up period. The average serum level of FSH 2-6 months after each course of treatment was significantly higher than before treatment (p<0.01), and there was a significant correlation with the cumulative dose of (131)I received (p<0.001). Reduced sperm count was found in 35.8% of the male patients, among whom 73.7% also showed reduced motility. In 36.8% of the patients with reduced sperm count (13.2% of the total), this finding was persistent during the follow-up period. Increased level of FSH was correlated with reduced sperm count in all doses (p<0.005). There was no significant correlation between serum levels of LH and testosterone with (131)I treatment in males. In females, no significant correlation between gonadal-hypophyseal hormones and treatment with (131)I was found, and there were no signs and symptoms of sexual dysfunction. Infertility was not noticed in any patient neither was there any case of abortion. Although female gonads are resistant to radioiodine treatment for thyroid cancer, in males this treatment may result in impairment of the gonadal function, which is transient most of the times. Spermatogenesis is especially sensitive to the radiation effect of (131)I treatment, and this effect is related to the cumulative radioiodine dose. To reduce gonadal complications, especially in males, treatment with (131)I should use the lowest possible doses. Also all necessary measures should be taken to reduce radiation dose to gonads.     

The early detection of metastatic differentiated thyroid cancer using 131I total body scan and treatment with 131I

With the purpose of achieving early detection and performing 131I therapy for metastatic lesions of differentiated thyroid cancer, we studied the clinical findings in 132 patients who underwent 131I total body scanning (131I TBS) between 1981 and 1990. Metastatic lesions were detected only by 131I TBS in 24 (18%) of the 132 patients. Of the 49 patients treated with 131I for metastases, 27 (55%) underwent total thyroidectomy and then had their metastatic lesions treated by 131I less than one year later. In the remaining 22 patients (45%), the metastatic lesions were treated with 131I from 1 to 31 years (mean: 8.4 years) after the initial thyroidectomy. We determined the optimal timing of 131I TBS following radical thyroidectomy to be 3-4 weeks by sequential measurement of the serum thyroid hormones, TSH, and Tg, and determination of the 123I uptake in residual or metastatic cancer of the neck after thyroidectomy. 131I TBS with simultaneous serum Tg determination were performed in 52 patients with metastases. Scans were positive in 43 of the 52 (83%) and the serum Tg level was greater than 10 ng/ml in 46 of the 52 (88%). Serum Tg was elevated in 9 patients with negative scans, while low Tg levels were found in 6 patients with positive scans. 131I therapy was effective in 49 of the 65 treated patients (75%), including 5 cures. Two patients worsened and 6 died. These 8 patients were all older than 56 years of age. Post-therapeutic 131I TBS demonstrated unsuspected metastatic lesions in 7 patients and had a higher detection rate for metastatic lesions than diagnostic 131I TBS. We conclude that 131I TBS with simultaneous Tg determination should be performed to detect metastatic lesions in all patients following positively total thyroidectomy for differentiated thyroid cancer, and that 131I treatment should be given when positive 131I uptake is detected in metastatic or residual cancer.     

Radiolabelled 5'-iodo-2'-deoxyuridine: a promising alternative to [18F]-2-fluoro-2-deoxy-D-glucose for PET studies of early response to anticancer treatment

We investigated the potential of radiolabelled 5-iodo-2'-deoxyuridine (IUdR) as a pharmacodynamic probe for use with positron emission tomography (PET) in studies of early proliferative response to anticancer treatment. Using the hormone-responsive rat mammary carcinoma OES.HR1, we used a multiple radiotracer method to examine treatment-induced changes in 24 h tumour retention of [131I]IUdR, uptake of [3H]2-deoxy-D-glucose ([3H]DG) together with [99mTc]hexylmethylpropylene amineoxine ([99mTc]HMPAO) uptake as a measure of blood flow. Radiotracer data were compared with macroscopic changes in tumour growth, and cell proliferation as determined by DNA histogram flow cytometry. From 4 days after tumour growth arrest induced by oestrogen ablation, a sustained fall in tumour cell proliferation was demonstrated, which was associated with reduced tumour uptake of each tracer. Whereas reduced levels of tumour [3H]DG could be accounted for by changes in blood flow, this was not the case for [131I]IUdR, which was found to be closely related to percentage S-phase cells within tumour (r = 0.73, p < 0.002). It was also estimated that residual levels of radioiodide may contribute significantly, to the low levels of retained radioactivity associated with responding tumours at 24 h following IUdR administration, suggesting that metabolite correction methods should be implemented as part of IUdR PET imaging protocols. We conclude that [124I]IUdR is a promising alternative to [18F]fluorodeoxyglucose ([18F]FDG) for the early assessment by PET of tumour response to treatments directed at targets associated with cell proliferation.     

Potential radiopharmaceuticals for the detection of ocular melanoma. Part I. 5-iodo-2-thiouracil derivatives

The tissue distribution of a number of 5-[131I]-iodo-2-thiouracil derivatives was measured in Syrian golden hamsters with Greene melanoma. These compounds were rapidly (in less than 1 h) distributed in all tissues, while in most tissues fast elimination (T1/2 1-3 h) was observed. Because of retention of the 131I activity in the tumour, high tumour/non-tumour tissue ratios were found (e.g. tumour/eye 2.3-10, tumour/skin 1.5-3) suggesting that some of these compounds might be used as melanoma delineating agents, when labelled with 123I.     

Zinc sulphate following the administration of iodine-131 on the regulation of thyroid function, in rats

Hyperthyroidism in men is often treated with high doses of iodine-131 ((131)I), which may induce radiation side effects to patients and their environment. These therapeutic doses of (131)I could be decreased, if the (131)I uptake of the thyroid gland of the patients could be increased. Zinc sulphate has been considered to exercise a protective role by maintaining the cellular integrity of the thyroid under various pathological states. The aim of our study was to study in Wistar rats whether zinc sulphate can after treatment of the thyroid gland with (131)I: a) increase the uptake of (131)I in the thyroid and b) stabilize the function of the follicular cells. If such a stabilization finally exists in men we could have favorable results like fewer cases of hypothyroidism after (131)I treatment of hyperthyroidism. To carry out these investigations, rats were divided into four groups comprising of eight animals each. Group I animals served as normal controls. Group II animals received a dose of 3.7 MBq of (131)I. Group III animals were supplemented with zinc (227 mg/L of drinking water) and animals in Group IV were given (131)I together with zinc sulphate as above. Our results showed that in Group II, serum levels of tetra-iodo-thyronine (T(4)) and tri-iodo-thyronine (T(3)) decreased significantly as a function of time following (131)I treatment. An increase in the levels of serum thyroid stimulating hormone (TSH) was noticed one week after (131)I treatment, becoming less pronounced with time. In Group II, thyroid uptake at 2h and at 24h was significantly decreased. In the same Group biological half life (T(biol)) of (131)I in the thyroid gland, was significantly elevated four weeks after the administration of (131)I and decreased eight weeks after. In Group IV animals, zinc sulfate after four weeks, induced normalization of elevated serum TSH levels and a further increase in the T(biol) of (131)I. After eight weeks in these animals, serum T(3) became normal and TSH remained at normal levels. Thyroid (131)I uptake at 2 and 24 h was increased as compared to Group II. Group III animals showed some increase in the levels of Na(+)K(+)ATPase and type 1,5'-deiodinase (5'-DI) as compared to normal rats of Group I. In conclusion, this study suggests the protective potential of zinc sulphate in the disturbed after (131)I treatment, thyroid function, thyroid hormones and TSH while the (131)I uptake was reduced. Thus, if this result is further confirmed, zinc sulphate may show to be a promising radioprotective agent for the thyroid gland.     

Radiotherapy with iodine-131 in recurrent malignant struma ovarii

Malignant struma ovarii is a very rare disease and, therefore, there is neither common agreement on treatment regimens nor sufficient follow-up experience. We present a case of a 49-year-old woman with malignant struma ovarii of the follicular type, who received ablative radioiodine treatment after thyroidectomy and surgical removal of the primary tumour. During followup examinations an increasing thyroglobulin level was found, caused by a tumour relapse with suspected urinary bladder infiltration on CT and proven uptake of radioiodine on whole-body scanning with iodine-131. After administration of 6 GBq¹³¹I, complete tumour regression was achieved with no evidence of a new relapse during a 30-month follow-up period. Correspondingly, repeated thyroglobulin measurements were all negative. This case demonstrates the benefit of combined surgical and radioiodine treatment of malignant struma ovarii for both monitoring and therapy of relapse or metastases; thus, the same therapeutic regimen as is employed in primary differentiated thyroid carcinoma may be recommended.     

Results of radioiodine therapy in patients with pulmonary metastases of differentiated thyroid cancer

Factors affecting the effect of 131I treatment and survival after pulmonary metastases in patients with differentiated thyroid cancer, were studied. Between 1984-1999, pulmonary metastases was observed in 51 out of 153 patients with differentiated thyroid cancer at our institution. Of these 41 patients had papillary and 10 follicular thyroid cancer. There were 37 females and 14 males with mean age (+/- S.D.) of 50.5 +/- 19.0 years. These 51 patients were subjected to 131I therapy. The effect of 131I treatment and the prognostic values of the following variables were examined: sex, age at the time of 131I treatment, histologic type of cancer, size of pulmonary metastases on CT, total-body scintigraphy with 201Tl and 131I, serum thyroglobulin levels and presence of metastases in distant sites other than lung. The effect of 131I treatment was evaluated by means of changes in the number and size of metastatic shadows on chest CT and by serum thyroglobulin levels. The minimum duration of follow-up was 12 months. Therapeutic 131I dose scans revealed detectable uptake in 25 of 51 patients. Therapeutic 131I dose uptake was achieved more frequently in patients under 40 years of age and in those with follicular cancers. Of the 51 patients, 13 were evaluated to be treated successfully. Those under 40 years of age, with 131I uptake in the lung and presence of other metastases showed a good response to treatment than others. Follicular cancer showed a more significant association with coarse type of lung metastases (> 5 mm in diameter on chest CT) and good 131I uptake than papillary cancer. Of all the variables studied, the best prognosis for survival was demonstrated by increased 131I uptake in pulmonary metastases. These results indicate that age, 131I uptake and presence of other metastases are important factors in predicting the effect of 131I treatment for pulmonary metastases of differentiated thyroid cancer.     

Implications of the uptake of 131I-radiolabelled meta-iodobenzylguanidine (mIBG) for the targeted radiotherapy of neuroblastoma

Selective uptake of radiolabelled meta-iodobenzylguanidine (mIBG) in neuroblastoma provides a possible approach to biologically targeted radiotherapy of this disease. A mathematical model was used to predict absorbed doses to tumours of varying size from therapeutic 131I-mIBG, based on measurements of 125I-mIBG uptake in surgically excised tumours from six patients. Two size categories of tumour target were considered: bulk tumour and microscopic disease. The predicted absorbed doses were compared with doses calculated to achieve a 50% probability of tumour cure. The analysis shows that the probability of tumour cure depends strongly on mIBG uptake, effective half-life of mIBG in tumour and tumour diameter. Small microtumours may be relatively resistant to mIBG treatment owing to the limited absorption of 131I beta-energy. The product of patient mass and percentage uptake per unit mass of tumour may be a useful indicator of therapeutic outcome when targeted radiotherapy is used for the treatment of paediatric tumours.     

Thyroglobulin and 131I uptake of remaining tissue in patients with differentiated carcinoma after thyroidectomy

In 158 thyroidectomized patients with well-differentiated non-metastatic thyroid cancer the results of serum thyroglobulin (Tg) determination and 131I uptake values established immediately before radioiodine treatment (19 days after surgery) were compared. In 113 patients (72%) Tg was above 6 ng ml-1 (lower limit of detection) and 131I uptake exceeded 2%. In 11 patients (7%) Tg was undetectable and 131I uptake less than 2%. In these cases a radioiodine treatment was not performed; the thyroid ablation was achieved by surgery only. In 34 patients (21%) with undetectable Tg, 131I uptake values, however, varied between 3 and 46% (mean value: 9.6%). Only in 4 of these 34 patients was TSH not maximally (50 microU ml-1) stimulated because of a shorter (9, 10, 11, 13 days) period from thyroidectomy. In conclusion, remaining thyroid tissue, highly stimulated by TSH, can trap a remarkable amount of radioiodine, but may be unable to produce detectable amounts of Tg. Therefore, in contrast to 131I, measuring Tg is insufficient to document the success of thyroid ablation. For the first follow-up study after ablative therapy, the uptake test with radioiodine is mandatory.     

Monitoring isotretinoin therapy in thyroid cancer using 18F-FDG PET

Treatment with isotretinoin (13-cis-retinoic acid, 13-cis-RA) is a recent additional option in advanced, otherwise intractable differentiated thyroid cancers. The aim of this study was to evaluate fluorine-18 fluorodeoxyglucose positron emission tomography (18F-FDG PET) in the prediction and the monitoring of response to 13-cis-RA therapy. Twenty-one patients with advanced differentiated thyroid cancers were investigated using 18F-FDG PET and iodine-131 whole-body scans before and 3, 6 and 9 months after initiation of 13-cis-RA therapy. After 9 months, 13-cis-RA treatment was discontinued and imaging procedures repeated 3 months later. Average 18F-FDG uptake (SUV) decreased significantly during 13-cis-RA therapy but subsequently increased in five of eight patients after withdrawal of 13-cis-RA. 18F-FDG uptake (SUV) 3 months after onset of 13-cis-RA therapy was significantly lower in patients who developed increased 131I uptake in their tumour sites than in patients with no subsequent increase in 131I uptake. There was no relationship between serum thyroglobulin level on the one hand and simultaneously measured 131I or 18F-FDG uptake on the other hand. There was a tendency towards lower 18F-FDG uptake in tumour manifestations with a better outcome. Therefore, 18F-FDG PET at 3 months after the start of treatment promises to differentiate between those patients who will eventually benefit from 13-cis-RA and those who will not. In conclusion, these data indicate that 18F-FDG PET is a useful tool for the evaluation and monitoring of adjuvant therapy with 13-cis-RA in thyroid cancer.     

Relative value of thallium-201 and iodine-131 scans in the detection of recurrence or distant metastasis of well differentiated thyroid carcinoma

Radioactive iodine (¹³¹I) has been found to be more sensitive and more specific than thallium-201 for the detection of distant metastases and thyroid remnants in the neck in cases of well-differentiated thyroid carcinoma. ²⁰¹Tl has been deemed particularly useful in localizing metastases or recurrence in patients with a negative ¹³¹I scan and abnormal levels of serum thyroglobulin (Tg). This study aimed to: (1) determine the value of ²⁰¹Tl imaging in localizing metastases or recurrence in patients with well-differentiated thyroid carcinoma, and (2) evaluate the false-positive and false-negative results of ¹³¹I and ²⁰¹Tl scintigraphy. Sixty-two thyroid remnant ablated patients who underwent simultaneous postoperative ²⁰¹Tl and ¹³¹I scans and and serum Tg determinations were evaluated. Fifty patients had papillary thyroid carcinomas and 12 had follicular thyroid carcinomas. ²⁰¹Tl imaging was performed before the ¹³¹I studies. Of the 62 patients who underwent ²⁰¹Tl imaging studies, 24 were found to have positive results, with local recurrence or distant metastases. Patients with positive results in the ²⁰¹Tl imaging studies tended to be older, were mor often male, had higher Tg levels and had a higher recurrence rate. Of these 24 patients, ten had negative diagnostic or therapeutic ¹³¹I scans. Concurrently, serum Tg levels were less than 5 ng/ml in five of these ten patients. Three patients were deemed false positive by ²⁰¹Tl scans; one had a parotid tumour, one a periodontal abscess and one lung metastasis. Among the 38 patients with negative ²⁰¹Tl scans, 11 had positive findings on ¹³¹I scans. Three had distant metastases: two with lung metastases and one with bone metastases. Patients with false-positive results on ¹³¹I scans included those with biliary tract stones, ovarian cysts, and breast secretion. Of the 27 patients with negative ²⁰¹Tl and ¹³¹I scans, 15 had elevated serum Tg levels. Among these, local recurrence followed by lung metastases was manifested in a 49-year-old male with papillary thyroid carcinoma. In conclusion, both ¹³¹I and ²⁰¹Tl scans are useful in the detection of recurrence or distant metastasis of well differentiated thyroid cancers. ²⁰¹Tl scan could in particular be used in patients with a negative ¹³¹I scan in conjunction with an elevated Tg level. Received 16 January and in revised form 8 April 1998     

Relationship between expression of the sodium/iodide symporter and 131I uptake in recurrent lesions of differentiated thyroid carcinoma

The sodium/iodide symporter (NIS) is known to be responsible for the active accumulation of iodide within the thyroid gland. We evaluated the relationship between the expression of NIS in primary or lymph node lesions and iodine-131 uptake in recurrent lesions of differentiated thyroid cancer. In 67 patients with differentiated thyroid cancer (5 follicular and 62 papillary carcinomas), the expression of NIS was analysed by immunohistochemical staining using polyclonal antibodies against human NIS. We used paraffin block tissues of primary tumours or metastatic lesions, and also assessed 131I uptake in recurrent lesions of thyroid cancer on post-operative 131I whole-body scan. Immunohistochemical staining was positive in 22 patients (32.8%), including 2 of 5 follicular and 20 of 62 papillary carcinomas. Recurrence was confirmed in 40 patients pathologically or clinically by serum thyroglobulin, 131I scan, fluorine-18 fluorodeoxyglucose positron emission tomography and/or computed tomography. Among these 40 patients, 28 showed positive uptake on 131I scan. Fourteen tumour specimens out of 28 (50%) were positive by NIS immunohistochemical staining. The remaining 12 patients with recurrent cancer showed negative 131I scans, and all specimens were negative by NIS immunohistochemical staining. Thus, NIS immunohistochemical staining predicted 131I uptake in recurrent cancer with a 100% positive predictive value and a 46.2% negative predictive value. There was no difference in the positivity of NIS according to the site of recurrence on 131I scan. Outcome of 131I therapy could be assessed in 22 of the 28 patients who showed 131I uptake in recurrent lesions. Patients with positive NIS immunostaining responded to 131I therapy better than did patients with negative immunostaining (P<0.05). In conclusion, NIS immunohistochemical staining showed a high positive predictive value in predicting iodine uptake. Positive immunohistochemical staining of human NIS in primary or lymph node lesions may predict 131I accumulation and effectiveness of 131I therapy in recurrent lesions.     

Treatment planning for 131I-mIBG radiotherapy of neural crest tumours using 124I-mIBG positron emission tomography.

Patients designated to receive 131I-meta-iodobenzylguanadine (mIBG) for the treatment of neural crest tumours have been scanned with 124I-mIBG using the MUP-PET positron camera. Uptake was detected in tumour sites in lung, liver and abdomen. The tomographic images produced have allowed estimates to be made of the concentration of mIBG in both tumour and normal tissue. From these data it is possible to predict the radiation doses that would be achieved using therapy levels (up to 11 GBq) of 131I-mIBG. The levels of tumour uptake are between 0.5 and 2.0 kBq/g indicating that the radiation doses to tumour would be in the range 3 Gy to 7.5 Gy.