Nomograms based on the novel platelet index score predict postoperative prognosis in endometrial cancer

Objective To identify preoperative platelet indexes with prognostic value and to develop and validate nomograms for predicting the survival of endometrial cancer (EC) patients. Methods A total of 1198 women who received primary surgical treatment between January 2008 and January 2017 were included in the study. Data were randomly divided into a training set (70%, N = 840) and an external validation set (30%, n = 358). Cox regression analysis was performed in the training cohort to identify independent prognostic factors and develop nomograms for survival rate prediction. Results High platelet count (PLT ≥350), high mean platelet volume (MPV ≥8.8) and low platelet distribution width (PDW <12.1) were independently associated with poor RFS and OS. PLT, MPV and PDW were thus incorporated in an innovative score called the platelet index score (PIS). The PIS was also an independent indicator, which was related to histology, lymph-vascular space invasion, lymph node involvement and FIGO stage (P = 0.007, P = 0.042, P < 0.001 and P < 0.001, respectively). Furthermore, we developed and validated two nomograms based on Cox regression models. The discriminative ability and calibration of the nomograms revealed good predictive ability, as indicated by the C-indexes and calibration plots. Moreover, both the IDI and NRI were improved. Conclusions Nomograms based on the PIS and clinicopathological features accurately predict recurrence-free survival and overall survival for EC patients.