Educational Objective: At the conclusion of this presentation, the participants should be able to understand the survival benefits of different treatment combinations in specific histological variants of intermediate risk differentiated thyroid cancer.
Objectives: To analyze the variant specific survival benefits of employing standardized treatment combinations of surgery (S), radioactive iodine ablation (RAI), and thyroid stimulating hormone suppression therapy (THST) in intermediate risk differentiated thyroid cancer (DTC).
Study Design: Retrospective database study.
Methods: The 2004-2017 National Cancer Database was queried for patients receiving definitive surgical treatment for intermediate risk papillary (PTC), follicular (FTC), or Hurthle cell (HTC) thyroid cancer. Cox proportional hazards and Kaplan-Meier analyses assessed for treatment associated mortality risk and overall survival (OS), respectively.
Results: A total of 65,736 patients were analyzed, with 72.2% females and an average age of 45.4┬▒15.4 years. S+RAI was associated with reduced mortality in PTC (hazard ratio [HR] 0.680; p<0.001) and FTC (HR 0.602; p=0.031). S+RAI+THST was associated with reduced mortality in PTC (HR 0.628; p<0.001), FTC (HR 0.490; p<0.001), and HTC (HR 0.520; p=0.006). On Kaplan-Meier analysis, S+RAI+THST was associated with greater OS than surgery and S+RAI for all DTC morphologies (all p<0.05). Regardless of the presence of lymphovascular invasion, nodal metastasis, or positive surgical margins, S+RAI and S+RAI+THST were associated with improved OS than surgery alone (all p<0.05). A survival benefit was not observed with the addition of THST in patients with lymphovascular invasion or N1A tumors.
Conclusions: Intermediate risk DTC exhibited varying susceptibilities to different treatment combinations depending on histology, with greatest responses to regimens that included RAI. This tendency extended to DTC cases with particular traits, including lymphovascular invasion, nodal metastasis, and positive surgical margins.