Objective Both pre-treatment prognostic nutritional index and platelet count were reported to be independent prognostic factors in epithelial ovarian cancer patients. However, their relationship has not been investigated. The aim of this study was to investigate the association between the pre-treatment prognostic nutritional index and platelet count, and to compare their utility as prognostic indicators for patients with epithelial ovarian cancer.

Methods Clinical data from epithelial ovarian cancer patients treated between April 2007 and March 2016 were collected and retrospectively reviewed. The association between the pre-treatment prognostic nutritional index and platelet count was evaluated using Spearman’s rank correlation coefficient. After determining the cut-off values for the pre-treatment platelet count and prognostic nutritional index for predicting disease-specific survival by time-dependent receiver operating characteristic (ROC) curve analysis, we compared the clinical utility of platelet counts and the prognostic nutritional index.

Results A total of 308 patients were included in the analysis. Median age was 57 (range 16–81) years. The International Federation of Gynecology and Obstetrics (FIGO) clinical stage at initial diagnosis was stage I in 137 patients (44.5%), stage II in 27 patients (8.8%), stage III in 96 patients (31.2%), and stage IV in 48 patients (15.6%). Most patients (37.7%) had serous adenocarcinoma. Of the 295 patients who underwent primary or interval debulking surgery, optimal debulking was performed in 240 patients (77.9%). Decresed pre-treatment prognostic nutritional index was correlated with increased pre-treatment platelet count (p<0.0001), and when compared, the prognostic nutritional index had a significantly greater area under the ROC curve value than the platelet count for predicting disease-specific survival (0.8348 vs 0.6413, p=0.0007). An elevated platelet count was significantly associated with a shorter disease-specific survival in epithelial ovarian cancer patients (p<0.0001). However, when the prognostic nutritional index was adjusted, an elevated platelet count did not provide any prognostic information (lower prognostic nutritional index, p=0.45; higher prognostic nutritional index, p=0.77).

Conclusions The pre-treatment prognostic nutritional index was superior to the platelet count for predicting disease-specific survival for epithelial ovarian cancer patients. Although pre-treatment thrombocytosis was reported to be an independent poor prognostic factor in epithelial ovarian cancer patients, it generally reflects a lower prognostic nutritional index, and did not provide any prognostic information when the prognostic nutritional index was adjusted.