Radio-guided occult lesion localization of cervical recurrences from differentiated thyroid cancer

Background: The aim of this work was to evaluate the application of he concept of ROLL (radio-guided occult lesion localisation) in order to identify non-palpable recurrences in the cervical region by differentiated hyroid cancer (DTC). This procedure makes it possible to perform minimally- invasive radio-guided surgery in a number of selected cases. Material and Methods: The new ROLL procedure was used in 32 DTC patients with loco-regional recurrent lesions. Three of the patients were subjected twice to the procedure. The patients had undergone total thyroidectomy and post-thyroidectomy 131I-ablation, and in somecases had been subjected to one or more cervical lymphadenectomies. Pre-operative labelling consists of ultrasound-guided intra-lesional administration of 99mTc-labeled human albumin macroaggregates (99mTc-MAA, 5e10MBq in 100e200 mL of saline), and was followed by scintigraphy of the cervical region, 2 to 18 hours before programmed surgery. A hand-held gamma-probe used intra-operatively made it possible to identify the labelled lesions. ROLL was employed by means of two different approaches: the former consisted of a selective minimally invasive excision of radiolabelled lesions in 12 patients (s-ROLL); the latter consisted of a modified radical neck dissection (MRND) after excision of radiolabelled lesions in 20 patients (d-ROLL). Results: A total of 59 lesions detected by ultrasound examination were radio-labelled by intra-lesional injection of 99mTc-MAA: of the 59 lesions, 41 were metastatic lymph nodes located in the latero-cervical regions, while 17 recurrent metastatic lesions were spotted in the suprajugular region (at VI level) and 1 lesion was in the high mediastinum. The mean echographic size of the lesions was 11.1_4.1 mm. Using the ROLL procedure, it was possible to localise and remove 59 out of 59 lesions (identification rate 100%), including those of 3 patients previously subjected to non-radioguided surgery, which had failed. Leakage of 99mTc-MAA in to the surrounding tissues during pre-operative labelling relatively hindered precise gamma-probe-guided identification of 3 lesions (in 2 patients). However, these lesions were identified and surgically removed on the basis of both radioactivity and palpation. Histopathological examination confirmed metastatic involvement in all the lesions and further metastases in the other nodes that had been removed. Furthermore, ROLL allows the extent of the cervical dissection to be maintained at a minimum. In our case, the procedure was particularly useful in the paratracheal region as there was no injury of the nerve or parathyroidectomy. After a median follow-up of 29 months, 19 patients showed no evidence of disease, whereas 12 patients developed loco-regional recurrences (in sites near to and/or different from those operated with ROLL), and 2 patients presented distant metastases. Statistical analyses showed no differences between the two surgical applications with regard to in-field relapse, diseasefree survival and overall survival. Conclusions: Radio-guided surgery carried out withROLLis possible in selected patients presenting with recurrent loco-regional DTC (including iodine- negative lesions). The ROLL procedure permits lesions that can be removed with limited invasiveness to be identified, in particular in patients who have already undergone cervical dissections. ROLL has proved to be particularly suitable in those cases in which the lesions were small, nonpalpableand/ or situated in sites that were surgically difficult to reach. Therefore, it is possible to use minimally invasive approaches, followed by shorter operating times and with reduced morbidity complications. Similar to other ROLLprocedures, the low radioactivity dose used does not produce significant radiation exposure either to the patients or to the staff members. In order to obtain optimal performance of the procedure, it is necessary to dispense with experts in ultrasound-guided tissue sampling in the cervical region, and to ensure close collaboration of a team that includes nuclear medicine specialists, surgeons and pathologists. The clinical importance of the ROLLprocedure in managing recurrentDTC should be debated, taking into account the information concerning the prognostic factors of the disease.