Predictors of morphofunctional features of somatotrophic tumors and of the effectiveness of treatment with first-generation somatostatin receptor ligands

Abstract

Introduction. Timely differential diagnosis between densely and sparsely granulated somatotrophic tumors allows predicting the most probable scenario of acromegaly course, receptor phenotype and proliferative potential of tumor cells, risk of continued postoperative growth, as well as the efficacy of planned drug therapy with first-generation somatostatin receptor ligands.Aim. To validate cytological, radiological and therapeutic predictors allowing to evaluate the morphofunctional composition of somatotrophic tumors and to predict sensitivity to first-generation somatostatin receptor ligands.Materials and methods. 525 patients (153 men) aged 60.2 ± 14.0 years receiving drug therapy with first-generation somatostatin receptor ligands for 72.0 ± 51.9 months were examined.Results. Treatment efficacy was evaluated according to the final level of IGF-1 index (≤1) and compared with the data of pathomorphologic (97 patients) and repeated radiologic (53 patients) examination. The influence of cellular composition of densely and sparsely granulated somatotrophic tumors on immunohistochemical and radiologic characteristics with the designation of leading predictors of morphologic identification of somatotrophic tumors was investigated. Additional radio markers for quantitative assessment of relative intensity of tumor signal on T2-, T1and (T2-T1)-weighted MRI for non-invasive differential diagnostics of densely and sparsely granulated somatotrophic tumors and determination of optimal treatment tactics were proposed. The expediency of using pharmacotherapeutic testing with short-term (3–6 months) first-generation somatostatin receptor ligands administration to assess the intactness of receptor and postreceptor mechanisms and to choose optimal drug therapy was substantiated.Conclusion. The precision approach based on comprehensive clinical, radiological, pathomorphological and functional characteristics allows stratification of patients with acromegaly to optimize treatment benefit. Achievement of acromegaly control in drug therapy with first-generation somatostatin receptor ligands depends on tumor volume and its hormonal activity, absolute and relative expression of the 2nd subtype of somatostatin receptors, severity of destructive changes and features of cellular composition. In case of refractoriness to first-generation somatostatin receptor ligands, the use of pegvisomant is expedient.