Surgical Confirmation of Incomplete Treatment for Primary Papillary Thyroid Carcinoma by Percutaneous Thermal Ablation: A Retrospective Case Review and Literature Review

Background: Recently, thermal ablation has been proposed for treating primary papillary thyroid carcinoma (PTC), triggering an extensive debate. This study aimed to analyze surgical outcomes of post-ablation cases to investigate the effectiveness and safety of thermal ablation in primary PTC. Methods: Primary PTC patients treated with thermal ablation were retrospectively searched for from the authors' medical record database prior to August 2017. The surgical patients met the following criteria: (i) primary PTC treated with thermal ablation, (ii) findings suspicious for malignancy of the post-ablation lesions on ultrasound or malignancy confirmed by cytology, or with clinical evidence of cervical lymph node metastasis (LNM), (iii) written informed consent for surgery, (iv) preference for definite diagnosis of the post-ablation lesions for the patients without evidence for malignant findings, and (v) tolerance of a thyroidectomy and without severe illness. Moreover, a systematic review of the literature was made to analyze relevant cases. Results: Twelve patients with an average age of 41.0 ± 13.6 years constituted the Fudan University Shanghai Cancer Center cohort in this study. Twenty-two foci with a mean size of 1.3 ± 0.7 cm were ablated percutaneously under ultrasound guidance. Residual PTCs were confirmed in all cases by histopathology, and LNM was present in 66.7% (8/12) of the patients. Intraoperatively, adhesion of the post-ablation lesions with the strap muscles was observed in six cases. Strap muscles were found to be cauterized in five cases, and notably the recurrent laryngeal nerve was involved in one case. Furthermore, seven relevant studies from Korea, Italy, and China were retrospectively reviewed, and incomplete ablation of primary PTC and omission of LNM by thermal ablation were observed frequently. Conclusions: Surgical therapy demonstrated incomplete ablation of primary PTC and omission of LNM by thermal ablation in this cohort of patients. Thermal ablation should be recommended with caution as treatment of operable patients with primary PTC.