To explore the classification of the therapeutic effect of patients with high-risk differentiated thyroid carcinoma (DTC) after surgery and ¹³¹I treatment, and to analyze the relevant factors that affect the therapeutic effect.

From January 2015 to January 2018, 256 high-risk DTC patients (70 males, 186 females; age (47.6±12.9) years) in the First Affiliated Hospital of Zhengzhou University were retrospectively analyzed. According to the 2015 American Thyroid Association(ATA)guidelines for therapeutic effect classification standards and the data measured during 6 months postoperative stimulation state, patients were divided into excellent response (ER) group, inderterminate response (IDR) group, biochemical incomplete response (BIR) group and structurally incomplete response (SIR) group, and the latter two groups were further combined into incomplete response (IR) group. χ² test, Fisher exact test and Kruskal-Wallis rank sum test were used to compare the clinical characteristics among the four groups. The receiver operating characteristic (ROC) curve of the relationship with ER and IR was established. Multivariate logistic regression was used to analyze the independent influencing factors of ER and IR. The subgroups with B-Raf proto-oncogene, serine/threonine kinase (BRAF)^V006E results were individually tested with χ² test of therapeutic efficacy.

There were 48.05%(123/256), 20.31%(52/256), 19.53%(50/256) and 12.11%(31/256) of DTC patients in ER, IDR, BIR and SIR groups respectively. The differences in gender (χ²=11.495, P=0.008), tumor size (H=21.368, P<0.001), N stage (χ²=42.012, P<0.001), distant metastasis (P<0.001) and pre-ablation stimulated thyroglobulin (psTg) level (H=142.829, P<0.001) were statistically significant among the 4 groups. The cut-off values of psTg for predicting ER and IR were 5.38 μg/L and 15.85 μg/L with the sensitivities of 79.7%(98/123) and 88.9%(72/81), with the specificities of 84.2%(112/133) and 91.4%(160/175) respectively. The cut-off values of tumor size for predicting ER and IR were 1.45 cm and 1.95 cm with the sensitivities of 63.4%(78/123) and 53.1%(43/81), with the specificities of 66.2%(88/133) and 74.3%(130/175) respectively. Multivariate regression analysis showed that female (odds ratio (OR)=2.305, 95% CI: 1.041-5.104), N0 stage (OR=2.365, 95% CI: 1.104-5.066), psTg<5.38 μg/L (OR=17.271, 95% CI: 8.561-34.841) and tumor size <1.5 cm (OR=2.194, 95% CI: 1.092-4.409) were independent predictors of ER; psTg≥15.85 μg/L (OR=81.544, 95% CI: 30.561-217.577), N1b stage (OR=3.617, 95% CI: 1.276-10.253) and tumor size >4.0 cm(OR=47.060, 95% CI: 2.449-904.360) were independent predictors of IR. The BRAF^V006E mutation rate of patients in the distant metastasis subgroup of the SIR group was significantly lower than that in ER, IDR, and BIR groups (χ² values: 20.852-40.905, all P<0.008).

About 48.05% of high-risk patients can achieve ER half a year after the initial treatment and be classified as low-risk again. Female, patients with N0 stage, psTg<5.38 μg/L and tumor size <1.5 cm have better therapeutic effect after initial treatment; patients with N1b stage, psTg≥15.85 μg/L and tumor size >4.0 cm have poor therapeutic effect after initial treatment.

Thyroid neoplasms; Radiotherapy; Iodine radioisotopes; Treatment outcome; Thyroglobulin; Forecasting