Effect of Rho GTPase activating protein 9 combined with preoperative ratio of platelet distribution width to platelet count on prognosis of patients with serous ovarian cancer

BACKGROUND: This study aimed to investigate the relationship between Rho GTPase activating protein 9 (ARHGAP9) combined with preoperative ratio of platelet distribution width to platelet count (PDW/PLT) and patients prognosis with serous ovarian cancer. METHODS: The clinical data of 80 patients with serous ovarian cancer treated in Jiangsu Cancer Hospital from May 2011 to May 2016 were analyzed retrospectively. We verified ARHGAP9 expression in The Cancer Genome Atlas (TCGA) database, then detected messenger RNA (mRNA) expression encoding ARHGAP9 in ovarian cancer tissue samples using reverse transcription quantitative polymerase chain reaction (RT-qPCR). These patients were divided into an ARHGAP9 low-expression group and an ARHGAP9 high-expression group. The optimal critical value of PDW/PLT was determined by receiver operating characteristic (ROC) curve. The patients were divided into low PDW/PLT group and high PDW/PLT group. Kaplan-Meier method and log-rank test were used for univariate survival analysis, Cox regression method was used for multivariate analysis, and then a nomogram was constructed for internal verification. RESULTS: The ARHGAP9 protein was highly expressed both in TCGA serous ovarian cancer database and the serous ovarian cancer tumor tissues. There were significant differences in menstrual status, the International Federation of Gynecology and Obstetrics (FIGO) stage and grade between the ARHGAP9 low expression group and ARHGAP9 high expression group (all P<0.05). There were significant differences in FIGO stage, lymph node metastasis, and ascites between the low PDW/PLT group and high PDW/PLT group (all P<0.05). Finally, 80 patients were included, with a mortality rate of 45.0% and a survival rate of 55.0%; the median progression-free survival (PFS) was 19 months, and the median overall survival (OS) was 62.5 months. Cox multivariate analysis showed that PDW/PLT and ARHGAP9 were independent risk factors for tumor progression (P=0.026 and P=0.028, respectively). In the internal validation, the C-index of the nomogram was 0.6518 [95% confidence interval (CI): 0.5685 to 0.7352], and the prediction model had certain accuracy. CONCLUSIONS: ARHGAP9 and PDW/PLT Decrease can significantly prolong OS and PFS in serous ovarian cancer patients. Therefore, ARHGAP9 can be used as a new predictive biomarker and may be related to the immune infiltration of serous ovarian cancer.