TUMOR MICROENVIRONMENT AS A BIOLOGICAL DETERMINANT IN HIGH-GRADE SEROUS OVARIAN CARCINOMA: IMMUNOHISTOCHEMICAL EXPRESSION OF BIOMARKERS

Abstract

Introduction. High-grade serous ovarian carcinoma (HGSOC) is the most aggressive form of epithelial ovarian cancer, characterized by pronounced molecular heterogeneity and increased resistance to conventional treatments. Investigating the expression of immunohistochemical markers within the tumor microenvironment—such as PD-L1, PD-L2, CD4, CD8, CD44, CD105, and CD31—offers valuable insights into tumor progression mechanisms and potential therapeutic targets.

Materials and Methods. A systematic review of recent scientific literature was conducted using PubMed, Scopus, and Web of Science databases. The selected studies evaluated the expression of the aforementioned immunohistochemical markers in HGSOC and correlated these findings with clinicopathological, prognostic, and therapeutic parameters.

Results. PD-L1 and PD-L2 were identified as central elements in immune evasion mechanisms, showing heterogeneous expression with variable prognostic implications. The correlation between PD-L1 and CD8+ lymphocytic infiltration highlights a complex relationship between immune activation and checkpoint regulation. The CD4/CD8 ratio confirmed the importance of immune infiltration in determining clinical outcomes and response to immunotherapy. In parallel, stromal markers CD44, CD105, and CD31 reflected complementary aspects of tumor aggressiveness: CD44 is involved in stem cell phenotype maintenance and chemotherapy resistance; CD105 in angiogenesis and epithelial–mesenchymal transition; and CD31 in vascular density and malignant dissemination. Integrating these biomarkers allows for the delineation of molecular profiles with prognostic and therapeutic relevance.

Conclusions. The combined expression of immunologic and stromal markers in HGSOC reflects both immune evasion and tumor remodeling mechanisms. Their integrated interpretation may contribute to more precise patient stratification and the development of personalized therapeutic strategies with the potential to significantly improve the prognosis of this aggressive malignancy.