Inflammation-based hematologic indices and overall survival in poorly differentiated thyroid carcinoma: a retrospective exploratory study

BACKGROUND: Poorly differentiated thyroid carcinoma (PDTC) is a rare and aggressive malignancy with limited prognostic tools. Inflammation-based hematologic indices, including the neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), and monocyte-to-lymphocyte ratio (MLR), have been investigated as potential prognostic markers in various cancers. However, their role in PDTC remains unclear and requires further exploration. METHODS: This retrospective single-center study included 39 patients with pathologically confirmed PDTC between June 2007 and June 2021. Preoperative hematologic parameters were collected within a standardized time window prior to surgery. NLR, PLR, and MLR were analyzed using dichotomized cut-offs derived from ROC analysis. Overall survival (OS) was evaluated using Kaplan-Meier analysis and Cox proportional hazards models. Multivariable models were constructed with age, TNM stage, and one inflammatory index at a time to minimize overfitting. Model discrimination was assessed using the concordance index (C-index). RESULTS: During a median follow-up of 56 months, 18 deaths occurred. In univariable analysis, age ≥ 55 years, advanced TNM stage, and elevated inflammatory indices were associated with worse OS. In reduced multivariable models, NLR and PLR remained associated with OS, while MLR did not. However, in the full multivariable model, only age ≥ 55 years was independently associated with OS. The inclusion of inflammatory indices modestly improved model discrimination. CONCLUSIONS: In this exploratory study, inflammation-based indices showed potential associations with overall survival in PDTC patients, but did not demonstrate independent prognostic value after adjustment for clinical variables. The clinical utility of these indices remains uncertain and requires validation in larger, prospective cohorts.