Long-Term Outcomes and Prognoses of Elderly Patients (≥65-Years-Old) With Distant Metastases From Well-Differentiated Thyroid Cancer During Radioiodine Therapy and Follow-Up.

Objective: The objective of this study was to investigate the clinicopathological characteristics, long-term outcomes, and prognostic factors of elderly patients with distant metastases at initial diagnosis from well-differentiated thyroid cancer (WDTC) during radioactive iodine (131I) treatment and follow-up. Methods: A retrospective review of medical records identified 183 elderly patients with DTC who underwent 131I treatment at our institution between 2006 and 2019. Results: In total, 57 elderly WDTC patients with distant metastases were enrolled in this study. After 131I treatment, 32 (56.14%) patients had 131I avidity and 25 (43.86%) had non-131I avidity; 35 (61.40%) cases were classified as radioiodine refractory (RR)-WDTC and 22 (38.60%) as non-RR-WDTC. At the end of follow-up, 25 (43.86%) patients had died and 32 (56.14%) were alive. The 5- and 10-year overall survival (OS) rates were 71.50% and 30.49%, respectively, while the 5- and 10-year disease-specific survival (DSS) rates were 76.89% and 48.71%, respectively. Multivariate analyses showed that gross extrathyroidal extension and RR-DTC were independent prognostic factors for poor OS (P=0.04 and P=0.03, respectively), while gross extrathyroidal extension, extrapulmonary distant metastases, and RR-WDTC were independent prognostic factors for poor DSS at the end of follow-up (P=0.02, P=0.03, and P=0.02, respectively). Conclusions: WDTC with distant metastases at initial diagnosis accounted for 31.15% of all elderly patients with DTC. Gross extrathyroidal extension and RR-DTC were the major factors associated with poor OS; gross extrathyroidal extension, extrapulmonary distant metastases, and RR-DTC were independent prognostic factors for poor DSS in elderly DTC patients with distant metastases.