Comparison of histopathological subtyping and PDL-1 status in high grade serous ovarian carcinoma with clinicopathological and prognostic data

High-grade serous ovarian carcinomas are divided into four molecular subtypes based on gene expression, with different prognoses and treatment responses, according to TCGA. Murakami et al classified these gene expression-based subtypes into mesenchymal, immunoreactive, solid proliferative, and papilloglandular subtypes by histopathological and immunohistochemical evaluation and found differences in survival outcomes. Miyagawa et al modified these criteria. In our study, 158 high-grade serous ovarian carcinoma cases were classified according to Murakami et al. criteria and Miyagawa et al. criteria by histopathological evaluation and differentiation cluster 8 immunohistochemistry on Hematoxylin Eosin stained slides and quadruple and binary histopathological classification was performed. Expression status of Programmed Cell Death Ligand-1 was evaluated by immunohistochemical study. The relationship between the created histopathological subtypes and Programmed Cell Death Ligand-1 expression, clinicopathological features and survival data were compared. In the 4 classifications, no significant statistical difference was found in progression-free and overall survival among the four subtypes according to both Murakami et al. criteria and Miyagawa et al. criteria. When binary classification was performed, progression-free and overall survival of the mesenchymal subtype was found to be statistically significantly shorter than the non-mesenchymal subtype. A significant relationship was observed between the immunoreactive subtype and Programmed Cell Death Ligand-1 immunoexpression. Programmed Cell Death Ligand-1 positive cases were found to have longer survival than negative cases, but statistical significance was not achieved. As a result, it is thought that changes should be made to the current criteria to make a 4 classification and that making a binary histopathological classification as mesenchymal and non-mesenchymal would be useful in terms of prognostic and treatment options, and that immunoreactive subtype cases and Programmed Cell Death Ligand-1 expression may be useful in determining the indication of immunotherapy agents that can be added to standard treatment.