High Ki-67 Expression is an Important Predictor of Good Outcomes after Radioiodine Therapy in PTC Patients: A Retrospective Study

Abstract

Abstract Objective This study aimed to evaluate the influence of primary Ki-67 expression in papillary thyroid cancer (PTC) and determine its association with clinical prognosis. Methods We assessed samples from 187 PTC patients taken from January 2015 to December 2019 for expression of Ki-67 labelling index (LI). We divided samples into low-LI (≤ 5%) and high-LI (5–10%) groups. Then, correlations of Ki-67 LI with clinicopathological variables were analyzed via χ2 test, and survival was evaluated using Kaplan–Meier curves. Furthermore, we used the Cox regression model to assess the diagnostic value of Ki-67 LI. Results Ki-67 LI was low in 85.0% (159/187) and high in 15.0% (28/187) of patients. All clinicopathological features were not significantly different between these two groups, except for Hashimoto's thyroiditis (χ2 = 4.936, P = 0.026) and stimulated thyroglobulin / serum antithyroglobulin antibodies (sTg / sTGAb) levels (χ2 = 7.932, P = 0.034). Moreover, Ki-67 LI was also an independent prognosticator of disease-free survival (DFS) in multivariate analysis (hazard ratio [HR] = 0.473; 95% CI, 0.233–0.960; P = 0.038). Conclusions Our data showed that high Ki-67 LI was associated with good outcomes in PTC patients after RAI therapy. Therefore, initial poor outcomes caused by high Ki-67 LI could be partially changed by RAI activities.