Pre-ablation stimulated thyroglobulin to TSH ratio as a strong predictor of non-generally satisfactory response to initial radioiodine therapy in papillary thyroid carcinoma patients undergoing lateral neck dissection.

BACKGROUND

The initial response to radioiodine (1³1I) therapy is a critical determinant of prognosis in papillary thyroid carcinoma (PTC) patients undergoing therapeutic lateral neck dissection (LND). This study aimed to identify predictors of non-generally satisfactory response (n-GR), defined as biochemical incomplete response or structural incomplete response, following initial ¹³¹I therapy.

METHODS

We retrospectively analyzed 145 PTC patients who underwent therapeutic LND and initial ¹³¹I therapy. Clinicopathological characteristics, preablation stimulated thyroglobulin (Pre-sTg), thyroid-stimulating hormone (TSH) levels, and lymph node metastasis parameters were evaluated. Multivariate logistic regression and receiver operating characteristic (ROC) curve analyses identified predictors of n-GR at 6 months post-therapy.

RESULTS

n-GR was observed in 24.2% (35/145) of patients. Multivariate analysis identified lateral neck metastasis burden (Odds Ratio [OR]: 1.026 per 1% increase, 95% Confidence Interval [CI]: 1.001-1.052, p = 0.040) and the Pre-sTg/TSH ratio (OR: 8.939 per 0.1 increase, 95%CI: 1.328-601.75, p = 0.041) as independent predictors of n-GR. The Pre-sTg/TSH ratio exhibited outstanding predictive performance (AUC = 0.955) with an optimal cutoff value of 0.127 (sensitivity: 91.4%, specificity: 90.9%). Integration of a Pre-sTg/TSH ratio > 0.127 into ATA recurrence risk categories significantly improved n-GR risk stratification: among intermediate-risk patients, the n-GR rate increased from 14.5% to 68.2%, and among high-risk patients, from 60.0% to 85.0%.

CONCLUSION

In our pilot study a Pre-sTg/TSH ratio > 0.127 significantly enhances risk stratification in PTC patients undergoing therapeutic LND when combined with ATA recurrence risk categories, supporting its potential use in personalizing treatment and follow-up strategies. Further validation in larger, multi-center cohorts is warranted.