Establishment and validation of a nomogram for predicting survival in patients with de novo metastatic nasopharyngeal carcinoma

Background and purpose No nomogram has been established for de novo metastatic NPC patients previously. Thus, we retrospectively involved 502 de novo NPC patients to develop a practical clinical tool by combining prognostic biomarkers to estimate individual risk. Methods The nomogram was based on a primary cohort involving 353 patients from 2007 to 2013; all independent prognostic factors were integrated for inclusion in the model. The predictive accuracy of the model was evaluated by concordance index (C-index). A calibration curve was used to compare predicted and observed survival. We confirmed the results using a validation cohort study on 149 patients enrolled from 2014 to 2016. Results Five independent prognostic factors derived from multivariable analysis were entered into the nomogram. The C-index of the nomogram was 0.724. The calibration curves for probability of 3- and 5-year overall survival (OS) showed satisfactory agreement between predicted survival and actual observed survival. The Kaplan–Meier survival curves showed a significant difference in survival among different risk groups according to the total score. All results were confirmed in the validation cohort. Conclusion We established a convenient nomogram that provides individual prediction of OS for patients with de novo metastatic NPC.