Análise da expressão de KI-67 em tumores neuroendocrinos da hipófise (PITNET’S)

Abstract

INTRODUCTION: Pituitary Neuroendocrine Tumors (PitNET's) are generally benign pathologies, but can cause great morbidity to patients through hormonal disorders, neurological deficits, refractoriness to drug therapies, recurrence after surgery, and even the occurrence of metastases. To identify aggressive tumors and guide optimized therapy, biomarkers such as Ki-67 have been studied. OBJECTIVE: The objective of this study is to analyze the impact of the Ki-67 index on tumor characteristics that determine worse surgical results. MATERIAL AND METHODS: 87 patients submited to endoscopic transsphenoidal surgery, with Ki-67 measured, were included. Correlations between tumor characteristics and the Ki-67 index were analyzed. Furthermore, the sample was divided into groups according to the degree of invasion (Knosp) and their characteristics were compared. Discrimination into clusters according to tumor data was also tested. RESULTS: The Ki-67 index was correlated with younger age (p < 0.001), lower degree of tumor resection (p < 0.001), and greater postoperative residual volume (p = 0.003), but not with volume or tumor diameter at diagnosis. Among the factors that negatively impacted the degree of tumor resection, volume (p = 0.001) and larger tumor diameter (p < 0.001) were revealed. A higher Ki-67 rate was observed in tumors with Knosp grade IV compared to all other Knosp grades (p < 0.001), but there was no difference between the other groups. The Knosp IV group also had a lower degree of resection when compared to all other groups, with a mean difference that ranged from 27.3 to 36% (p < 0.001). The variables postoperative residual volume, sex, degree of resection and Knosp were able to discriminate the sample into 3 clusters of regular quality. One of the clusters showed significant differences in relation to the others in tumor diameter, volume at diagnosis, degree of resection and post-surgical volume, but without differences in relation to age or Ki-67. CONCLUSION: The Ki-67 index correlates with characteristics that determine worse surgical results. Therefore, new studies must evaluate its prognostic impact to guide more effective treatments for patients with PitNET’s.