Serum cytokine profiles in papillary thyroid carcinoma patients with lung metastases: characteristics and the relationship with prognosis

OBJECTIVE: To characterize the serum cytokine profiles of papillary thyroid carcinoma (PTC) patients with lung metastases prior to initial 131I therapy and to evaluate the predictive value of such profiles for therapeutic response. METHODS: A retrospective study was conducted on PTC patients who received thyroidectomy at the Affiliated Hospital of Xuzhou Medical University from June 2021 to December 2024. Propensity score matching was utilized to a group with lung metastasis and select a control group without distant metastasis. Serum levels of 12 cytokines were compared between groups. Correlations between clinicopathological features and cytokines within the metastasis group were analyzed, and receiver operating characteristic curves were utilized to assess the predictive efficacy of cytokines for 131I treatment failure. RESULTS: From 2397 eligible patients, 51 patients with confirmed lung metastases were matched with 102 control patients (1 : 2 ratio) to form a final cohort of 153 patients. Levels of IL-6, IL-10, IL-12p70, IFN-γ, and TNF-α were significantly higher in the lung metastasis group (P < 0.05). Subgroup analysis showed that IL-10 levels were elevated in older patients (>55 years) and IL-6 levels correlated strongly with the size of pulmonary lesions (>2 cm). Baseline IL-6 and TNF-α demonstrated robust predictive value for the outcome of adjuvant 131I therapy (progressive disease vs. nonprogression). IL-6 yielded an area under the receiver operating characteristic curve of 0.772 (95% confidence interval: 0.633-0.912, P < 0.05), optimal cutoff value: 7.85 pg/ml (specificity: 78.2%, sensitivity: 80.6%) and TNF-α yielded an area under the receiver operating characteristic curve of 0.746 (95% confidence interval: 0.592-0.899, P < 0.05), optimal cutoff value: 15.32 pg/ml (specificity: 72.5%, sensitivity: 71.8%). CONCLUSION: Preradiotherapy serum IL-6 and TNF-α levels serve as indicators of metastatic burden and potential predictors of 131I resistance. They offer a complementary objective basis for personalized prognostic assessment in PTC patients with pulmonary involvement.