Supplementary Material for: A prospective study on defining the indications of prophylactic level IB radiotherapy in nasopharyngeal carcinoma based on a risk score model

Objective: To investigate clinical evidence for defining the indications of prophylactic level IB radiotherapy in nasopharyngeal carcinoma (NPC). Methods: We conducted a phase 2 prospective study in 116 newly diagnosed patients with NPC treated by intensity-modulated radiotherapy (IMRT). Whether level IB was irradiated based on the risk score model (RSM). Two groups based on RSM were obtained: low risk and high risk. Omission of level IB irradiation was conducted in low risk group, otherwise level IB was contoured as part of the treatment target. Grade 2 or worse xerostomia at 12 months was assessed by the European Organization for Research and Treatment of Cancer (EORTC) QLQ-H&N35 questionnaire. Results: At a median follow-up of 16months (range, 1-26 months). None patients developed failures at level IB. The 1-year overall survival (OS), locoregional recurrence-free survival (LRRFS) and distant metastasis-free survival (DMFS) rates were 98.3%, 97.2% and 95.8%, respectively. At 12 months xerostomia side-effects were reported 90 of 126 alive patients, grade 2 or worse xerostomia at 12 months was significantly lower in the low risk group than in the high risk group. Conclusion: Omission of level IB irradiation was feasible for patients with low-risk IB lymph nodes metastasis.

研究目的：明确鼻咽癌（nasopharyngeal carcinoma, NPC）预防性IB区放疗适应证的临床证据。方法：本研究纳入116例初诊鼻咽癌患者，采用调强放射治疗（intensity-modulated radiotherapy, IMRT）开展一项Ⅱ期前瞻性研究。根据风险评分模型（risk score model, RSM）决定是否对IB区进行放疗，将患者分为低风险组与高风险组。低风险组豁免IB区放疗，高风险组则将IB区纳入治疗靶区并勾画。采用欧洲癌症研究与治疗组织（European Organization for Research and Treatment of Cancer, EORTC）QLQ-H&N35量表评估患者治疗12个月时≥2级口干症发生情况。结果：中位随访时间为16个月（范围：1~26个月）。所有患者均未出现IB区复发。1年总生存率（overall survival, OS）、局部区域无复发生存率（locoregional recurrence-free survival, LRRFS）及无远处转移生存率（distant metastasis-free survival, DMFS）分别为98.3%、97.2%和95.8%。治疗12个月时，126例存活患者中共90例报告口干症不良反应；低风险组≥2级口干症发生率显著低于高风险组。结论：对于IB区淋巴结低危的鼻咽癌患者，豁免IB区放疗具有可行性。