Molecular Characteristics and Survival Rates in the Patients with Gastrointestinal Stromal Tumors: A Retrospective Single-Center Study

Background/Objectives: Gastrointestinal stromal tumors (GISTs) are the most common malignant mesenchymal tumors that compose a heterogeneous group due to various molecular alterations. This study aimed to determine the molecular characteristics of patients with GIST treated between 2002 and 2017 and to follow their overall survival (OS) over 20 years. Methods: DNA was isolated from surgical biopsies of 490 patients with gut sarcomas and was analyzed using PCR and Sanger sequencing of hotspots of KIT, PDGFRA and BRAF genes. Immunohistochemical (IHC) staining was used to determine SDHB expression. Results: 417 GIST patients, including 13 children, were included; females predominated (male-to-female ratio 0.65), median age of 55.4 years old. KIT and PDGFRA mutations were found in 288 GISTs (69.1%) and 52 (12.5%), respectively. A total of 25 KIT and 3 novel PDGFRA mutations were revealed in 30 GISTs. KIT/PDGFRA mutations were not detected in 77 (18.5%) GISTs; among them were 2 NF1 GISTs, 10 with BRAF mutation, 14 with SDHB deficiency, and 3 “pediatric” GISTs. The overall survival (OS) of 280 GIST patients over more than 20 years. Genetic changes have a certain prognostic value in addition to such factors as tumor size, mitotic index, and location. The OS of GIST patients with KIT mutations was lower than that of patients with PDGFRA mutation, BRAF mutation, or SDHB deficiency, but the difference was non-significant. Conclusions: Our study highlights the heterogeneous nature and molecular features of GISTs in Russian population. The precise molecular characterization of the tumor should be considered an integral part of modern personalized GIST treatment.