High Ki-67 labeling index correlates with aggressive clinicopathological features in papillary thyroid carcinoma: a retrospective study

BACKGROUND: Papillary thyroid carcinoma (PTC) is the most prevalent thyroid carcinoma that possesses a wide range of biological behavior. Various clinical and histopathological features, including BRAFV600E profile, are used to stratify the risk of disease recurrence in thyroid carcinoma. Recent studies have taken an interest in the potential of the proliferation index, Ki-67, in predicting the aggressive nature of PTC. METHODS: This is a single-center, retrospective study that included 92 PTC cases diagnosed at the Department of Anatomical Pathology, Faculty of Medicine/Dr. Cipto Mangunkusumo Hospital, from January 2019-December 2022. Continuous and categorical analysis of Ki-67 labeling index (LI) was studied and compared with various clinicopathological features and BRAFV6000E status. RESULTS: Ki-67 LI was identified in PTCs (range = 0.1–17.1%, median = 2.45%). Higher Ki-67 LI (median value and Ki-67 LI > 5%) is significantly correlated with older age, advanced stage, lymph node metastasis, distant/organ metastasis, aggressive histological subtypes, unencapsulated tumors, lymphovascular invasion, extrathyroidal extension, and BRAFV600E mutation. CONCLUSION: The proliferation activity shown by Ki-67 LI correlates with aggressive tumor characteristics and may imply possible prognostic significance in diagnosing PTC.