Establishment and validation of a nomogram for predicting the benefit of concurrent chemotherapy in stage II nasopharyngeal carcinoma: A study based on a phase III randomized clinical trial with 10-year follow-up

Abstract

Background and purpose: Our previous phase III randomized trial demonstrated that the addition of concurrent chemotherapy to radiotherapy (RT) could improve survival in stage II nasopharyngeal carcinoma (NPC). Based on the study, we sought to develop a nomogram for predicting the 5-year and 10-year survival of patients with stage II NPC and estimating the benefit of concurrent chemoradiotherapy (CCRT) for individual patients.

Materials and methods: Data of 199 enrolled patients from the original trial was analyzed to build a nomogram. Overall survival (OS) was the primary endpoint. The discrimination and calibration capacities were evaluated using Harrell Concordance Index (C-index) and calibration curves, respectively. Internal validation of the nomogram was performed by a separate cohort of 306 patients from the same cancer center.

Result: In training cohort, patients in CCRT group achieved higher 5-year and 10-year OS compared with patients in RT group. Three independent prognostic factors, which were age, N stage and treatment method from multivariable analysis were extracted to enter the nomogram. T stage was also included due to its importance in clinical decisions. The Harrell C-index of the nomogram in training and validation cohort was 0.748 and 0.653 respectively. The calibration curves showed an acceptable agreement between prediction and observed probability.

Conclusion: We developed and validated a nomogram to predict the 5-year and 10-year OS in stage II NPC patients. The nomogram could serve as a pragmatic tool in clinical decisions to estimate the individual risk of stage II patients and identify those who could benefit from chemotherapy.

Keywords: Chemotherapy; Nasopharyngeal carcinoma; Nomogram; Radiotherapy; Survival.