Diagnostic 131I whole body scanning after thyroidectomy and ablation for differentiated thyroid cancer.

OBJECTIVE: To assess the value of the diagnostic whole body (131)I scan after thyroidectomy and (131)I ablation. DESIGN: Retrospective analysis of all patients with differentiated thyroid cancer treated in one centre between 1990 and 2000. RESULTS: A total of 153 consecutive patients who underwent diagnostic scanning following ablative therapy were identified. This diagnostic scan was positive in 20 patients (13%) and faintly positive in 16 patients (11%). The majority (117 patients) had negative scans. Of the 20 patients with positive scans, four received no further treatment, nine showed no abnormal uptake following a second ablative (131)I dose and seven had uptake in the thyroid bed (six) or in neck nodes (one) after repeat ablation. OUTCOME: In the group with positive scans, the four patients who received no further treatment and the nine with a negative second ablation scan remained disease free during follow-up. No patient with a positive diagnostic scan received additional (131)I therapy which would not otherwise have been given based on the clinical findings, serum thyroglobulin (Tg) values or the presence of anti-Tg antibodies. Ten of the patients with negative scans developed recurrent disease which was always detected clinically or by a rising serum Tg value. CONCLUSIONS: Diagnostic whole body (131)I scans add little extra information and in our experience do not influence patient management. They should be reserved for patients in whom serum Tg levels are unreliable because of the presence of antibodies or when there is clinical suspicion of tumour.

Long-term results in elderly patients with differentiated thyroid carcinoma.

BACKGROUND: The authors assessed the biologic behavior of differentiated thyroid carcinoma in patients age 70 years or older and evaluated factors that influenced long-term survival. METHODS: Among 1448 patients with differentiated thyroid carcinoma who were treated at the authors' institution over the past 60 years, 111 patients were identified who were age 70 years or older at the time of their initial diagnosis (range, 70-93 years). The authors conducted a retrospective analysis of the outcome of these 111 patients, who had a median follow-up of 9 years (range, 2-9 years). RESULTS: There were 83 female patients and 28 male patients (female to male ratio, 3:1). Fifty-eight tumors were papillary, 46 tumors were follicular, and 7 tumors were Hürthle cell carcinoma. Eighty percent of patients presented with a thyroid mass, and 70% of tumors were pathologic stage T3 (pT3) or pT4. Lymph node disease was evident at presentation in 44% of patients, and distant metastases were documented at diagnosis in 23% of patients. Forty-six patients underwent total thyroidectomy, and the remaining patients underwent subtotal thyroidectomy or biopsy only. Radioiodine was administered to 80 patients, and external beam radiotherapy was administered to 19 patients. The cause specific survival rates were 75%, 50%, and 50% at 5 years, 10 years, and 15 years, respectively. Multivariate analysis showed that the presence of metastases was the most important independent prognostic factor for survival. External beam radiotherapy was associated with a poorer prognosis, in that it was reserved for patients with either inoperable disease or residual disease after surgery and patients with no uptake of radioiodine. CONCLUSIONS: A large proportion of thyroid tumors showed extrathyroid spread and distant metastases, which frequently were not iodine-avid. The prevalent histologic type was papillary, often with features of poor differentiation. Thyroid carcinoma in the elderly appears to behave more aggressively, and they have a less favorable prognosis compared with younger adults.

Testicular dose and fertility in men following I(131) therapy for thyroid cancer.

OBJECTIVE: Young adults with differentiated thyroid cancer are treated with high doses of radioiodine and have an excellent long-term prognosis. However, there is limited information on the effects of this treatment on the gonads and fertility in male patients. We have reviewed the outcome of treatment in our centre with respect to male fertility. We have also assessed directly the radiation dose received by the testes. DESIGN: Retrospective analysis of males attending the thyroid clinic at the Royal Marsden Hospital for treatment of differentiated thyroid cancer. A prospective study was also performed to assess radiation dose to testes in 14 consecutive patients attending for thyroid cancer treatment. PATIENTS: Males under the age of 40 years at the time of treatment with a minimum of 3 years follow-up. MEASUREMENTS: Number of children fathered by patients and number of congenital malformations. For the prospective study: gonadal function assessed by serum FSH, LH and testosterone measurements; radiation dose to the testes (Gy) measured by thermoluminescent dosimetry. RESULTS: Fertility was assessed in 122 men with a median follow-up of 21 years (range 3-39) of whom 93 were under active follow-up. One hundred and six children were fathered by 59 patients; the remainder had no wish to have children. No major malformations were reported. Of these 59 patients, 12 had received a single 3 GBq ablation dose, 19 had been treated with up to 14 GBq radioiodine and 28 had received up to 44 GBq. In 14 patients followed prospectively, the median estimated radiation dose to each testis was 6.4 cGy following 3 GBq, 14.1 cGy following 5.5 GBq and 21.2 cGy following 9.2 GBq. There was a transient elevation in serum FSH after radioiodine which normalized within 9 months from the last administration. CONCLUSIONS: Radioiodine treatment for thyroid cancer may result in transient impairment of gonadal function. The radiation dose absorbed by the testis after a single ablative dose of radioiodine is well below that associated with permanent damage to germinal epithelium and the risk of infertility in these patients is minimal. Patients requiring multiple administrations for persistent or metastatic thyroid cancer may be at greater risk of gonadal damage although even in this group, we found no evidence of infertility.