The role of hormonal status, morphological subtypes and proliferative marker Ki-67 labeling index on long-term outcomes in patients with acromegaly: a single tertiary center’s experience

Abstract

Aims: Acromegaly is a rare disorder resulting from benign growth hormone secreting pituitary adenomas. Many factors affect long-term outcomes in acromegaly. In this study we aimed to investigate effects of hormonal status, morphological subtypes, immunohistochemical expression of pituitary hormones and Ki-67 labeling index on long-term outcomes in patients with acromegaly. Methods:. We collected the medical and pathological records of sixty-four patients who underwent surgery for growth hormone (GH) secreting somatotroph tumors between 2005-2017. Results: The remission rate after surgery was 48% (31/64) in all patients (33% for macroadenomas, 94% for microadenomas; p <0.001) with a median follow up of 48 months (13-198). There was no significant relationship between Ki-67 labeling index and remission status (p=0.140). The remission group were significantly older than the nonremission group [47 (21-64) vs 36 (18-56); p=0.012]. We found a statistically significant positive correlation between IGF-1 levels and Ki-67 labeling index (r=+0.382, p=0.004). Also, there was a significant positive correlation between tumor size and GH (r=+0.368, p=0.027). There was no difference between densely and sparsely granulated adenomas in terms of surgical remission (p=0.866). In multivariate regression analysis, tumor size ≥ 10 mm (macroadenoma) was significant independent variable in predicting remission [ 95% CI [16.95 (1.92-142)]; p=0.011 ]. The baseline cortisol levels was correlated negatively with the Ki-67 labeling index (r=+0.293, p=0.02). Conclusion: The Ki-67 labeling index is not associated with surgical remission in patients with acromegaly. However, the Ki-67 labeling index was higher in younger patients and those with larger adenoma size.