99mTc-sestamibi radio-guided surgery of loco-regional 131Iodine-negative recurrent thyroid cancer

Aim: We report here our experience in a larger series of differentiated thyroid cancer (DTC) patients who had been treated by Tc-99m-sestamibi radio-guided surgery (RGS) for (131)Iodine (I-131)-negative loco-regional recurrent disease. Methods: Fifty-eight patients with loco-regional I-131-negative recurrent disease from DTC were studied with Tc-99m-sestamibi directed RGS using a hand-held I I-mm gamma probe as an intra-operative detector. Patients were selected for RGS on the basis of (a) progressive increase of serum thyroglobulin (Tg) levels after first treatment during follow-up, (b) negative high dose (100 mCi, 3.7 GBq) I-131 whole-body scan, and (c) positive pre-operative Tc-99m-sestamibi scintigraphy for the presence of loco-regional recurrent disease. There were 41 papillary (I "tall" cell variant). 13 follicular and 4 Hurthle cells tumours. In 14 patients thyroid cancer recurred in the thyroid bed while cervical lymph node metastases were found in 37 patients, and 7 patients had recurrent disease both in the thyroid bed and in cervical lymph nodes. Results: At bilateral neck exploration, 147 metastastic foci ranging from 4 mm to 51 rum in largest diameter (mean tumour diameter = 17.3 +/- 9.5 mm) were removed. Eighty-five of them (58%) had been pre-operatively identified at Tc-99m-sestamibi scintigraphy. After RGS. serum Tg levels normalised in 43 of 58 patients (serum Tg < 2 ng/ml - they were considered disease-free), serum Tg remained slightly increased in 12 patients without evidence of metastatic disease at scintigraphic and radiologic imaging (serum Tg < 10 ng/mg they were considered living with microscopic disease), while serum Tg significantly increased up to values > 900 ng/ml in 3 patients who developed lung metastases. The mean lesion to background Tc-99m-sestamibi uptake ratios decreased in all 58 patients (p < 0.0001). Postsurgical follow-up ranged 6-72 months (mean +/- SD = 29.6 +/- 13.5 months). The operating surgeon assessed RGS as very useful in 14 patients in whom metastatic foci were embedded in fibrotic tissues or located behind blood vessels, useful in 22 patients, moderately useful 17 patients and not useful in 5 patients. Conclusion: Our data suggest that a Tc-99m-sestamibi intra-operative gamma probe can be used to identify and guide resection of recurrent loco-regional tumour in DTC patients with I-131-negative loco-regional metastatic foci. (c) 2007 Elsevier Ltd. All rights reserved.