Radioiodine Refractory Follicular Thyroid Cancer and Surgery for Cervical Relapse

SIMPLE SUMMARY: Differentiated thyroid cancer includes papillary (PTC) and follicular thyroid cancer (FTC). Eighty-five percent of patients are cured by thyroidectomy and one single radioiodine treatment. Relapse is rare and can mostly be cured by a second radioiodine therapy. Between 5% and 10% of differentiated thyroid cancers are, or become, unresponsive to radioiodine treatment during the course of disease. For these patients repeated surgery is the only curative option: chemotherapy and external beam radiation play a minor role, targeted therapy is started in a palliative setting for rapidly progressing tumors. In most studies on radioiodine refractory differentiated thyroid cancer, there is a predominance of PTC, due to its higher incidence compared to FTC. In the present study we critically evaluate indications and outcome of repetitive cervical surgery for radioiodine refractory FTC at our university clinic. ABSTRACT: Compared to its more common counterpart papillary thyroid cancer (PTC), follicular thyroid cancer (FTC) has a less favorable outcome, due to its higher incidence of distant metastases and advanced stages at diagnosis. Despite radioiodine (RAI) avidity, metastatic FTC often progresses after radioiodine treatment (RAIT). We aimed at evaluating the indications and outcomes of surgery for cervical relapse of radioiodine refractory FTC. Patients receiving RAIT between 2005 and 2015 at the University Hospital of Cologne, Germany, were screened. Patients with FTC were identified. Demographics, clinic-pathologic characteristics, treatment, and outcome of patients diagnosed with RAI refractory FTC, who underwent cervical surgery in the course of disease, were analyzed. FTC accounted for 8.8% of all thyroid carcinomas undergoing RAIT. In 35.2% of FTC patients, disease persisted or recurred despite a cumulative mean RAI activity of 18.7 GBq ± 11.6 (follow-up 83.5 ± 56.7 months). Distant metastases were diagnosed in 75% of these patients, as bone (57.6%), lung (54.6%), and liver metastases (12.1%). Cervical relapse occurred in 63.6% of these patients and was treated in 57.1% with surgery with, and without, external beam radiation therapy (EBRT). Despite surgery and EBRT, in 75% of patients, cervical relapse recurred again. In conclusion, surgery for cervical radioiodine refractory FTC relapse is often performed in metastatic setting. With and without EBRT, cure is rare, although metastases can appear radioiodine avid. Early biological marker and systemic treatments for these patients are still needed.