PSAT372 Percutaneous Polidocanol Injection as an Alternative Treatment Differentiated Thyroid Cancer Oligometastases

INTRODUCTION: Differentiated thyroid cancer (DTC) presents central lymph node metastasis in 20-50% and lateral in 12-81% of patients and ipsilateral recurrence after lateral neck dissection occur in 8-26%. The treatment of choice is surgical reintervention with subsequent administration of radioiodine. Treatment with radioactive iodine together with surgical reintervention aimed at compartments dissection provides variable remission rates in some cases of only 30-50%. Surgical reintervention carries a greater risk of complications such as recurrent laryngeal nerve injury, secondary postoperative hypoparathyroidism and morbidity associated with fibrosis formation in the surgical bed. Due to the complications, minimal invasive techniques (MIT) have been described for the treatment of unresectable and/ or proliferative oligomestastases, such as percutaneous ethanol injection (PEI), radiofrequency ablation, microwave ablation and laser ablation. PEI is described for the ablation for thyroid cysts, thyroid and parathyroid adenomas and cervical lymph node metastases. It´s used in the treatment of lesions smaller than 10 mm2 and represents a berry picking type intervention. It requires multiple sessions and can cause pain due to extravasation, skin necrosis, laryngeal necrosis, and damage to the recurrent laryngeal nerve. PEI´s greatest limitation is the uneven and unpredictable ablation area. Guidelines don´t contemplate it as the first line of MIT, highlighting thermal ablation`s (TA) usefulness, however it´s mentioned to consider its selection according to resources availability. After stating the inconveniences with PEI and difficulties related to the TA availability, in our center we have used polidocanol as a safer and more effective alternative to ethanol. Percutaneous polidocanol injection (PPI) requires fewer sessions and lower dose, and its administration technique is like PEI. PPI is described only as an alternative treatment for PEI recurrent pure cysts. OBJECTIVE: Determine the efficacy of PPI for DTC oligometastasis treatment. Study Design: An experimental, prospective, comparative, and analytical study. Patients older than 18 years were selected, with oligometastasis due to DTC in whom ablation with polidocanol 3% was performed, considering therapeutic efficacy the disappearance of the treated node and reduction of thyroglobulin. RESULTS: 27 patients were studied, a total of 60 lymph nodes. 22 women and 5 men, age 47.0±14.2 years, all with papillary thyroid cancer and structural incomplete response, with a cumulative RAI dose of 50±176 mCi, Thyroglobulin without stimulation was 3.06±2.9 ng/dl. Number of sessions was 1 in 71.4%. Mean polidocanol 3% used was 1.9±1.28ml. Follow-up time was 7.8±4.9 months. Initial tumor volume 5.9±1.3 ml, tumor volume at follow-up 0.88± 0.21, (p=0.00), control thyroglobulin was 0.55±0.8.1 (p=0.10). Remission was modified in 52.4%, reduction in 42.9%, stability in 4.8% No patient documented progression. CONCLUSION: Polidocanol is safe and effective so it should be considered for the treatment of oligometastasis in DTC, in selected cases when thermal ablation techniques are lacking. Presentation: Saturday, June 11, 2022 1:00 p.m. - 3:00 p.m.