 The degree of cytoreduction achieved during primary debulking surgery, PDS, is an important prognostic factor for the survival of patients with epithelial ovarian cancer, EOC. Laboratory parameters such as Ca125, neutrophil to lymphocyte ratio, NLR, monocyte to lymphocyte ratio, MLR, and platelet to lymphocyte ratio, PLR, can help predict the outcome of PDS. In this study, we found that Ca125, NLR, and MLR are independent significant predictors of the degree of tumor reduction achieved during PDS. Additionally, MLR, especially in combination with other parameters, may be useful in determining prognosis and selecting the best treatment option, PDS or neo-wageven chemotherapy plus interval debulking surgery for ovarian cancer patients. This article was authored by Anna Rebecca Kovacs, Anita Salina, Kinkso-Sara Kovacs, and others.