Clinical characteristics and long-term outcomes for parapharyngeal metastases of well-differentiated thyroid cancer during 131 I therapy and follow-up.

Abstract

Parapharyngeal metastases (PPM) are rarely observed in patients with well-differentiated thyroid cancer (WDTC). Radioiodine (131 I) therapy has been the main treatment for metastatic and recurrent DTC after thyroidectomy. This study was performed to evaluate the clinicopathological features and long-term outcomes associated with survival of patients with PPM at the end of follow-up. In total, 14,984 consecutive patients with DTC who underwent 131 I therapy after total or near-total thyroidectomy from 2004 to 2021 were retrospectively reviewed. Therapeutic efficacy was evaluated using the Response Evaluation Criteria in Solid Tumours v1.1 and logistic regression analysis. The disease status was determined using dynamic risk stratification. Disease-specific survival (DSS) was assessed using the Kaplan-Meier method and a Cox proportional hazards model. Seventy-five patients with PPM from WDTC were enroled in this study. Their median age at the initial diagnosis of PPM was 40.2 ± 14.1 years, and the patients comprised 32 men and 43 women (male:female ratio, 1.00:1.34). Of the 75 patients, 43 (57.33%) presented with combined distant metastases. Fifty-seven (76.00%) patients had 131 I avidity and 18 had non-131 I avidity. At the end of follow-up, 22 (29.33%) patients showed progressive disease. Sixteen of the 75 patients died; of the remaining 59 patients, 6 (8.00%) had an excellent response, 6 (8.00%) had an indeterminate response, 10 (13.33%) had an biochemical incomplete response, and 37 (49.33%) had a structural incomplete response. Multivariate analysis confirmed that age at initial PPM diagnosis, the maximal size of PPM, and 131 I avidity had significant effects on progressive disease of PPM lesions (p = .03, p= .02, and p < .01, respectively). The 5- and 10-year DSSrates were 98.49% and 62.10%, respectively. Age of ≥55 years at initial diagnosis of PPM and the presence of concomitant distant metastasis were independently associated with a poor prognosis (p = .03 and p = .04, respectively). The therapeutic effect for PPM was closely associated with 131 I avidity, age at initial PPM diagnosis, and maximal size of PPM at the end of follow-up. Age of ≥55 years at initial diagnosis of PPM and the presence of concomitant distant metastasis were independently associated with poor survival.