2896 - A Predictive Model Based on the Dosimetric Parameters of the Parotid Stem Cell Region to Assess the Recovery of Radiation-Induced Xerostomia in Long-Term Survivors of Nasopharyngeal Carcinoma after Radical Radiotherapy
Presenter(s)
J. Zang1, M. Zhang1, J. B. Liu1, C. Liu1, Y. Zhou2, Z. Yang3, Y. Zhu4, L. Zhao5, and M. Shi6; 1Department of Radiation Oncology, Xijing Hospital, Air Force Medical University, Xi'an, China, 2Department of Radiation Oncology, The First Affiliated Hospital of Bengbu Medical University, Bengbu, China, 3Department of Radiation Oncology, General Hospital of Ningxia Medical University, yinchuan, China, 4Department of Radiotherapy, Baoji Central Hospital, baoji, Shaanxi, China, 5StateKey Laboratory of Holisticntegrative Managementof Gastrointestinal Cancersand Department of RadiationOncology,Xijing Hospital,Fourth Military MedicalUniversity, Xi'an, China, 6Department of Radiation Oncology, Xijing Hospital, Fourth Military Medical University, Xi’an, Shanxi, China
Purpose/Objective(s): Recent studies on head and neck cancer have revealed that the radiation dose to the stem cell region (SCR) of the parotid gland is more significantly associated with occurrence of sever xerostomia. However, for nasopharyngeal carcinoma (NPC) patients, where the bilateral parotid glands are near high-dose areas, further research is needed to understand how radiation to the parotid stem cell region (SCR) affects xerostomia recovery. This multicenter study aims to explore SCR radiation dosimetric parameters and clinical factors that influence recovery from radiation-induced xerostomia in long-term survivors.
Materials/Methods: This study included 648 NPC patients from four medical centers in China who received radical radiotherapy. Recovery from radiation-induced xerostomia was analyzed using patient-reported outcomes (PRO) and physician-assessed outcomes (PAO). The Cox proportional hazards model identified key clinical and dosimetric factors for recovery, aiming to develop an integrated prediction model. Prognostic performance was evaluated with time-dependent area under the receiver operating characteristic curve (AUC), and Kaplan-Meier curves estimated recovery across different risk groups.
Results: With a median follow-up of 42 months (range: 16-120 months), 220 patients (33.9%) reported no recovery from xerostomia, while 215 patients (33.2%) showed no recovery according to physician assessments. XeQol scores improved in physical abilities (p = 0.000), pain/discomfort (p = 0.002), psychological well-being (p = 0.000), and social interaction (p = 0.000) over 1 to 5 years post-radiation therapy in all patients. Multivariate analysis identified age, induction chemotherapy, SCR Dmean, and SCR V20 as key predictors of recovery. A nomogram model using these factors outperformed individual factors in predicting recovery (3-year AUC: 0.704, 5-year AUC: 0.754 for PRO; 3-year AUC: 0.712, 5-year AUC: 0.78 for PAO). Based on the median score of model, the cohort was divided into high-risk and low-risk groups, with the low-risk group showing a higher recovery rate (p<0.001).
Conclusion: A predictive model that incorporates SCR dosimetric parameters and clinical variables can effectively forecast xerostomia recovery based on both patient-reported and physician-reported outcomes.