Clinical outcome and influencing factors of differentiated thyroid cancer with biochemical incomplete response.

Purpose: The aim of our study was to investigate the clinical outcomes and predictive factors in patients with biochemical incomplete response (BIR) after initial radioiodine therapy (RAI).

Materials & methods: This retrospective study enrolled 198 patients with BIR from two institutions and stratified them into a training cohort (Qingdao cohort, n = 144) and an external validation cohort (Beijing cohort, n = 54). The patients were classified as having incomplete response (IR) or non-IR disease at the final follow-up. Univariate and multivariate analyses identified IR predictors in the training cohort. A nomogram was developed using the training cohort and was validated in the validation cohort using calibration curves, decision curve analysis (DCA), and receiver operating characteristic analysis.

Results: Age, recurrence risk, pre-stimulated thyroglobulin (ps-Tg), and BRAF^V600E mutation were independent predictors of IR in the training cohort. The nomogram identified ps-Tg as the strongest predictor of IR risk, followed by the BRAF^V600E mutation, age, and recurrence risk. The calibration curves demonstrated excellent agreement between the predicted and observed probabilities. DCA confirmed favorable clinical utility.

Conclusions: This validated nomogram provides a clinically useful tool for quantifying IR risk in BIR patients, supporting personalized management decisions after initial RAI.