Factors predicting the risk of biochemical incomplete response in well-differentiated thyroid cancer after total thyroidectomy.

BACKGROUND: Differentiated thyroid cancer (DTC) is the most common endocrine carcinoma with an overall good prognosis. However, persistent or recurrent disease (P/R disease) and incomplete biochemical response (BIR) are causes of morbidity. Histopathology and TNM stage may not predict P/R disease and BIR in all patients. Various clinical parameters, histopathological features and preablative-stimulated thyroglobulin (presTg) have been proposed to predicts P/R disease. However, there is uncertainty for presTg cutoff and diagnostic accuracy. The study's objective was to predict the BIR before radioiodine ablation from available clinical, histopathological and biochemical parameters. METHODS: A retrospective, single-center study, including DTC patients, was done. Demography and factors predicting BIR evaluated. RESULT: In comparison to the patients in remission, patients with BIR were older (P = 0.042), had higher presTg (P < 0.001), and lymph nodes (LN) metastases [central or lateral compartment (P < 0.001)]. Visualization of LN on whole-body scan (P = 0.014), higher TNM stage (P = 0.001) and distance metastasis (P < 0.001) were also associated with BIR. On multivariate analysis, high presTg (P < 0.001) and LN metastases (LNscan and histopathologically proven LN involvement, P < 0.001) were associated with BIR. A presTg level ≥12.30 ng/ml has high sensitivity (90.6%) and specificity (80.6%) to predict the BIR (odds ratio 39.90). CONCLUSIONS: The presTg and LN involvement are robust markers that predict BIR. A raised presTg level with LN metastases and nonvisualization of the LN on the whole-body scan is a worrying feature for the future BIR. We propose the inclusion of high presTg as a high-risk factor in DTC.