Scientific Abstracts: Basic Science and Technology
Objective: Cryoablation for recurrence of well-differentiated thyroid carcinoma has not been rigorously reported, especially regarding freeze protocols, antibiotic prophylaxis, anatomic approach and sedation/recurrent laryngeal nerve monitoring. Herein we report our protocol and approach, rooted in existing surgical paradigms of the head and neck, for cryoablation of well-differentiated thyroid cancer within ATA (American Thyroid Association) guidelines performed by IR as part of a collaborative IR-Endocrine Surgery service line.
Methods: Retrospective study. Over a 12 month period from 2018-2019, 4 patients with 5 FNA-proven local recurrences 3 cm or smaller were discussed in tumor board. Patients were treated with ultrasound- and CT-guided cryoablation using various organ displacement and dermoprotective techniques. Follow-up imaging was obtained and patients were followed clinically in IR clinic. All cryoablations (and same-session biopsies) were performed by a single operator with 6 years of experience with cryoablation. Procedural antibiotic prophylaxis was provided using a protocol of clindamycin and metronidazole to cover for oral flora, based on paradigms of head and neck surgery and tracheal proximity.
Results: Technical success was 100% (5/5) defined as iceball coverage of the lesion for a minimum of one 10 minute freeze cycle. One or two cryoprobes were used per lesion. Lesions were located adjacent to typically more than one of the following: trachea, carotid artery, jugular vein, subclavian artery, skin. All patients had stable or decreased nodule size at the 2 week imaging mark. One patient (15 x 15 mm nodule adjacent to trachea, jugular, subclavian) had complete resolution of nodule at 1 month follow-up with no complications. One patient (10 x 13 mm nodule adjacent to carotid, jugular, subclavian) had complete resolution of nodule at 1 month follow-up with mild resolving Horner Syndrome, and separately had recurrent laryngeal nerve palsy treated with vocal fold injection and subsequently underwent cryoablation of second lesion with follow-up pending. One patient (10 x 10 mm nodule adjacent to jugular, carotid, trachea) had complete nonenhancement at 2 week follow-up imaging but was lost to follow-up (international patient). Finally, one patient with level 2a nodule had temporary stridor from lidocaine contact with her only functional recurrent laryngeal nerve, and no doppler signal in the lesion with 10% decreased size of lesion (21 x 26 mm nodule) at 1 month follow-up ultrasound.
Conclusions: Cryoablation can be safely applied adjacent to major vessels and the trachea in the neck with only light sedation and on an outpatient basis. The initial results are promising however complete shrinkage of the tumor may take longer than with thermal ablation which contracts the tissue. Commercially available probe selection, temperature goals, freeze cycles, and organ displacement/dermoprotective maneuvers factored into the success rate for these cases. Management of complications including stridor, recurrent laryngeal nerve palsy and Horner Syndrome was predictable by the position of the treatment target, and could be counseled during informed consent in IR clinic.