Relationship between patient and physician-rated xerostomia and dose distribution to the oral cavity and salivary glands for head and neck cancer patients after radiotherapy

Introduction: Xerostomia is a frequent complication after curative intended radiotherapy (RT) for head and neck squamous cell carcinoma (HNSCC). Assessment of xerostomia is commonly done by the physician. The aim of this study is to investigate the relation between patient and physician-rated xerostomia and to predict the degree of xerostomia from patients with self-reported xerostomia based on delivered doses to the oral cavity, parotid, and submandibular glands. Material and methods: During a 2-year period, consecutive HNSCC patients attending the follow-up clinic were included. All included patients had self-reported xerostomia, and completed the disease-specific EORTC QLQ-H&N35 questionnaire. The physician assessed the degree of xerostomia with the DAHANCA toxicity scale and was blinded for the EORTC score. Oral cavity, parotid, and submandibular glands (OAR) were delineated on the planning CT according to international guidelines. DVH were extracted from treatment plans. Logistic regression tested the relation between mean doses, patient characteristics, and xerostomia scores. Differences between DVH values and scoring of xerostomia were analyzed with a Kruskal–Wallis test. The relation between xerostomia and dose distributions was further investigated using principal component analysis (PCA). Results: In total, 109 patients were included in the study. A weak correlation was seen between patient and physician-rated toxicity (p = .001), however, in general patients reported more toxicity than physicians. For EORTC score ≥2, the multi-variable analysis was significant for doses to the oral cavity, tobacco status and use of xerogenic medication. Neither the DVH analysis nor the PCA found any clear distinction between xerostomia scores for EORTC or DAHANCA and investigated OARs. Conclusion: Patients tended to report higher scores of xerostomia than the physician. PCA indicated a complex relation between doses to the OAR and xerostomia scores, showing e.g., that reducing doses in one organ was on the expense of increased dose to another organ.

引言：口干症（Xerostomia）是头颈部鳞状细胞癌（HNSCC）根治性放射治疗（RT）后常见的并发症。目前临床中通常由医师对口干症进行评估。本研究旨在探讨患者自评与医师评分的口干症之间的相关性，并基于口腔、腮腺及下颌下腺的受照剂量，对存在自评口干症的患者的口干程度进行预测。

材料与方法：本研究纳入了2年内于随访门诊就诊的连续性头颈部鳞状细胞癌患者。所有入组患者均存在自评口干症，并完成了针对头颈部肿瘤的欧洲癌症研究与治疗组织QLQ-H&N35（EORTC QLQ-H&N35）问卷。医师采用DAHANCA毒性评分量表评估口干程度，且对患者的EORTC问卷评分设盲。研究人员按照国际指南在计划CT图像上勾画了口腔、腮腺及下颌下腺等危及器官（OAR）。从治疗计划中提取剂量体积直方图（DVH）数据。采用逻辑回归分析平均受照剂量、患者基线特征与口干症评分之间的相关性。通过克鲁斯卡尔-沃利斯检验分析剂量体积直方图参数与口干症评分之间的差异。进一步采用主成分分析（PCA）探讨口干症与剂量分布之间的关联。

结果：本研究共纳入109例患者。患者自评与医师评分的口干毒性之间仅存在弱相关性（p=0.001），且总体而言患者报告的毒性程度高于医师。当EORTC评分≥2分时，多变量分析显示口腔受照剂量、吸烟史及致口干药物使用情况具有统计学意义。无论是剂量体积直方图分析还是主成分分析，均未发现EORTC或DAHANCA口干症评分与所研究的危及器官之间存在明确的区分度。

结论：患者报告的口干症评分普遍高于医师评分。主成分分析结果显示，危及器官受照剂量与口干症评分之间存在复杂关联，例如，降低某一器官的受照剂量往往会导致另一器官的受照剂量升高。