Revalidation of a prognostic score model based on complete blood count for nasopharyngeal carcinoma through a prospective study

OBJECTIVE: In our previous work, we incorporated complete blood count (CBC) into TNM stage to develop a new prognostic score model, which was validated to improve prediction efficiency of TNM stage for nasopharyngeal carcinoma (NPC). The purpose of this study was to revalidate the accuracy of the model, and its superiority to TNM stage, through data from a prospective study. METHODS: CBC of 249 eligible patients from the 863 Program No. 2006AA02Z4B4 was evaluated. Prognostic index (PI) of each patient was calculated according to the score model. Then they were divided by the PI into three categories: the low-, intermediate-and high-risk patients. The 5-year disease-specific survival (DSS) of the three categories was compared by a log-rank test. The model and TNM stage (7th edition) were compared on efficiency for predicting the 5-year DSS, through comparison of the area under curve (AUC) of their receiver-operating characteristic curves. RESULTS: The 5-year DSS of the low-, intermediate-and high-risk patients were 96.0%, 79.1% and 62.2%, respectively. The low-and intermediate-risk patients had better DSS than the high-risk patients (P<0.001 and P<0.005, respectively). And there was a trend of better DSS in the low-risk patients, compared with the intermediate-risk patients (P=0.049). The AUC of the model was larger than that of TNM stage (0.726 vs. 0.661, P=0.023). CONCLUSIONS: A CBC-based prognostic score model was revalidated to be accurate and superior to TNM stage on predicting 5-year DSS of NPC.