The influence of stimulated thyroglobulin and lymphocyte subsets before radioiodine therapy on the therapeutic response in patients with intermediate- and high-risk papillary thyroid carcinoma

The aim of the present study was to investigate the factors influencing the short-term response to the initial radioiodine therapy (RT) course in patients with intermediate- and high-risk papillary thyroid carcinoma (PTC). A total of 182 patients with intermediate- and high-risk PTC who underwent RT in our hospital from March 2018 to October 2020 were retrospectively enrolled. The patients were divided into incomplete response (IR) and nonincomplete response (Non-IR) groups according to the response observed in clinical follow-up within 6-12 months after RT. Univariate and multivariate logistic regression analyses were used to investigate the effects of 15 observed factors on the response to RT. Receiver operating characteristic (ROC) curve analysis was used to determine the value of factors found to be significant in multivariate analyses for predicting an IR. A total of 182 patients with intermediate- and high-risk PTC were analyzed; the percentage of patients with a Non-IR was 61.54% (112/182), and the percentage of patients with an IR was 38.46% (70/182). The CD4(+) T-cell percentage (t = 4.757, P = 0.000), CD4/CD8 (z = - 2.632, P = 0.008), stimulated thyroglobulin (sTg) level (z = - 8.273, P = 0.000) and M stage (chi(2) = 17.823, P = 0.000) of the two groups were significantly different. Multivariate analysis showed that only the sTg level (OR: 1.116, 95% CI 1.068-1.165, P < 0.001) and CD4(+) T-cell percentage (OR: 0.909, 95% CI 0.854-0.968, P = 0.003) were independent factors associated with the therapeutic response to RT. The cutoff sTg level and CD4(+) T-cell percentage for predicting an IR were 7.62 mu g/L and 40.95%, respectively. The sTg level and CD4(+) T-cell percentage were verified to be independent predictive factors of RT response. Higher sTg levels and lower CD4(+) T-cell percentages were related to an IR in patients with intermediate- and high-risk PTC.