Tissue Immune Response In Epithelial Ovarian Carcinoma.

2625 Background: Epithelial ovarian cancer (EOC) is a highly malignant disease with a fatal outcome for most patients. During recent years immunological mechanisms have proven important in relation to the treatment and prognosis of cancer, but within EOC the knowledge is still sparse. Understanding the importance of immune markers to the prognosis of ovarian cancer is essential for the future treatment of EOC. The aim of the present study was to investigate the prognostic impact of intratumoral PDL-1 expression, T cells, neutrophil granulocytes (NG) and Natural Killer (NK) cells in a population based cohort. Methods: All patients diagnosed with ovarian cancer in Denmark in 2005 were included in the study. Immunohistochemical staining was performed on tumor tissue from 412 patients. Antibodies for PD-L1, T cells (CD8), NG (CD66b), and NK cells (CD57) were used. Cell densities were analyzed using a digital image analysis method. The primary endpoint was overall survival (OS). Results: In high grade serous carcinoma (HGSC) the median OS in patients with a high level of tumor infiltrating T cells was 37 vs 25 months in patients with a low level(p = 0.0008). Multivariate analysis showed a hazard ratio (HR) of 0.72 (p = 0.020). The median OS in patients with a high level of tumor infiltrating NK cells was 45 vs 29 months in patients with a low level (p = 0.0310). Multivariate analysis showed a HR of 0.67 (p = 0.041). PD-L1 and NG had no statistically significant impact on OS. Only T cells showed prognostic significance across histological subtypes with a HR of 0.72 (p = 0.007) in favor of a high density of T cells. Conclusions: The present population based study demonstrated prognostic importance of tumor infiltrating T cells and NK cells in HGSC. Neither PD-L1 nor NG held prognostic significance.