Aggressive variants of papillary thyroid carcinoma: characteristics, influencing factors, and effectiveness of radioiodine therapy

To investigate the pathological characteristics of aggressive variants of papillary thyroid carcinoma (PTC) and evaluate the efficacy of radioiodine (RAI) therapy for these variants.

We analysed 129 patients with aggressive variants of PTC and compared them to those of 4460 patients with non-aggressive variants. And we examined the efficacy of RAI therapy in 70 eligible patients with aggressive variants of PTC and 2530 eligible patients with non-aggressive variants of PTC.

Aggressive and non-aggressive variants of PTC demonstrated a greater degree of variability in terms of age, multifocality, capsular invasion, vascular invasion, extrathyroidal invasion, lymph node metastases, disease stage, risk stratification, N stage, comorbid with Hashimoto thyroiditis (HT) and comorbid with nodular goiter (NG). Propensity score matching method showed poor efficacy of RAI treatment in patients with aggressive variants of PTC compared with non-aggressive variants. Multifactorial analysis showed that comorbid NG was an independent risk factor for poor effectiveness of RAI treatment for aggressive PTC variants ((hazard ratio (HR) 3.027; 95% confidence interval (CI), 1.295–7.075).

Aggressive variants of PTC demonstrated a higher degree of aggressiveness and poor efficacy of RAI therapy compared to non-aggressive variants, especially comorbid with NG, which may require higher therapeutic 131I dosage.