Prognostic nomogram of xerostomia for patients with nasopharyngeal carcinoma after intensity-modulated radiotherapy.

Xin-Bin Pan,Long Chen,Song Qu,Yang Liu,Xiao-Dong Zhu,Kai-Hua Chen,Shi-Xiong Liang,Ling Li,Zhong-Guo Liang

doi:10.18632/aging.102717

Abstract

Xerostomia is a common radiation-induced late complication after radiotherapy. Identifying predictive factors for xerostomia will lead to better treatments and improve the quality of life. This study was conducted to establish an effective predictive nomogram for xerostomia by assessing stage I-IVb (AJCC 7th edition) NPC patients between September 2015 and March 2016. Xerostomia was evaluated via the RTOG/EORTC system. The primary endpoint was grade 2-3 xerostomia 1 year after treatment. The predictive factors for xerostomia were analysed using logistic regression analysis. A nomogram was constructed based on combining the predictors and clinical variables. In total, 102 patients with grade 0-1 xerostomia and 93 patients with grade 2-3 xerostomia were included. The independent predictive factors for xerostomia were V25, V30, V35, and V45 of the ipsilateral parotid gland and mean dose of the contralateral parotid gland. The calibration plot for the probability of xerostomia showed good agreement between prediction by the nomogram and actual observation. The concordance index of the nomogram for predicting xerostomia was 0.796 (95% CI: 0.735-0.857, P <0.001), which was higher than any single dosimetric parameter. Our results indicated that the nomogram provided a more accurate prediction of grade 2-3 xerostomia 1 year after treatment.

Highlights

Nasopharyngeal carcinoma (NPC) is an endemic cancer in Southern China [1, 2]
The concordance index of the nomogram for predicting xerostomia was 0.796, which was higher than any single dosimetric parameter
The dosimetry parameters of the parotid glands have been commonly used for the prediction of xerostomia

Summary

INTRODUCTION

Nasopharyngeal carcinoma (NPC) is an endemic cancer in Southern China [1, 2]. NPC is a radiosensitive malignant tumor. The incidence of clinically significant xerostomia was more than 30% after intensity-modulated radiotherapy (IMRT) [4,5,6]. Identifying predictive factors for xerostomia will lead to better treatments for patients with risks of severe xerostomia and improve the quality of life [9,10,11]. The potential predictive factors of xerostomia after IMRT in NPC patients remain unclear. The xerostomia clinical factors require further assessment, including age, sex, pathology, tumour stage, chemotherapy, and volume of the parotid glands.

RESULTS

DISCUSSION

MATERIALS AND METHODS