ABSTRACT: OBJECTIVE:The need for tailoring ovarian cancer treatments to individual patients is increasing. This study aimed to evaluate the prognostic value of pretreatment laboratory test data for predicting the response and survival outcomes of platinumbased chemotherapy in ovarian cancer. METHODS:We enrolled 270 patients with ovarian cancer diagnosed at the Kyoto Medical Center (n=120; group A) and Kyoto University (n=150; group B). Data on 9 blood parameters (neutrophil to lymphocyte ratio [NLR], platelet to lymphocyte rate [PLR], C-reactive protein, lactate dehydrogenase [LDH], glucose, total cholesterol, high-density lipoprotein [HDL], low-density lipoprotein, and triglyceride levels), cancer pathology, cancer stage, cytoreduction outcomes, serum cancer antigen 125 levels, platinum-free interval (PFI), disease-free survival (DFS), and overall survival were assessed retrospectively. RESULTS:NLR, PLR, LDH, and HDL were significantly different in advanced stage patients (P<0.001, <0.001, 0.029, and <0.001, respectively). The Kaplan-Meier curves revealed that high LDH level (?250 U/L) was associated with reduced PFI (P=0.037 and 0.012) and DFS (P=0.007 and 0.002) in groups A and B, respectively. High NLR (?4) was associated with reduced DFS in both groups (P=0.036 and 0.005, respectively). LDH showed higher area under the curve (AUC) values in predicting platinum resistance with a PFI of less than 6 months and 12 months (AUC=0.606 and 0.646, respectively) than NLR. In the multivariate analysis, LDH remained significant (P=0.019) after adjusting for the 9 blood parameters. CONCLUSION:Serum LDH level may possibly predict platinum resistance and prognosis in ovarian cancer and may be useful when developing precision medicine for individual patients.