Heterogeneity of small intestinal tumors: from molecular-genetic characteristics to diagnostics and treatment (literature review)

Objective. Small intestine tumors (SITs) are a heterogeneous group of rare neoplasms (1–3% of all gastrointestinal tumors) characterized by the difficulty of early diagnosis, a variety of histological types, and the lack of standardized treatment protocols.

Purpose of a study: to determine how the pathogenetic features of the main histological types of small intestinal tumors influence the tactics of diagnostic algorithms and treatment methods.

Material and Methods . A systematic analysis of scientific publications was conducted, including systematic reviews, original studies, clinical guidelines, and rare clinical cases indexed in the PubMed, Scopus, Web of Science, and Russian Science Citation Index (RSCI) databases.

Results. It was established that the most common malignant neoplasms of the GI tract are neuroendocrine tumors (NETs) and adenocarcinomas, which are characterized by a more aggressive course. Gastrointestinal stromal tumors (GISTs), on the other hand, are less common. The diagnostic paradigm has undergone a significant evolution: from intraoperative detection to multimodal stratification, including capsule/balloon enteroscopy, CT and MR enterography, as well as molecular imaging methods (PET-CT with 68Ga somatostatin analogs for NETs and 18F-FDG for GISTs). Immunohistochemical typing (chromogranin A, synaptophysin, CD117, DOG1, CDX-2, Ki-67) and molecular-genetic profiling (KIT/PDGFRA mutations, MSI status, 18q deletion), which determine the choice of targeted and immunotherapy as well as the optimal extent of surgical treatment.

Conclusion . The combined use of CT/MR enterography, enteroscopy, PET/CT, and molecular typing allows for personalized surgical intervention, improving prognosis for these rare and heterogeneous tumors. The main unresolved issues remain the late detection of small bowel tumors (especially adenocarcinomas) and the insufficient number of large randomized trials to develop standardized patient management guidelines.

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