The purpose of this study was to determine the negative predictive value (NPV) of a 12- to 14-wk posttreatment PET/CT for 2-y progression-free survival (PFS) and locoregional control (LRC) in patients with p16-positive locoregionally advanced oropharyngeal cancer (LA-OPC). Study was a secondary endpoint in NRG-HN002, a noncomparative phase II trial in p16-positive LA-OPC, stage T1-T2, N1-N2b or T3, N0-N2b, and ≤10 pack-year smoking. Patients were randomized in a 1:1 ratio to reduced-dose intensity-modulated radiotherapy (IMRT) with or without cisplatin. Methods: PET/CT scans were reviewed centrally. Tumor response evaluations for the primary site, right neck, and left neck were performed using a 5-point ordinal scale (Hopkins criteria). Overall scores were then assigned as negative, positive, or indeterminate. Patients with a negative score for all 3 evaluation sites were given an overall score of negative. The hypotheses were NPV for PFS and LRC at 2-y posttreatment ≤ 90% versus >90% (1-sided P value, 0.10). Results: A total of 316 patients were enrolled, of whom 306 were randomized and eligible. Of these, 131 (42.8%) patients consented to a posttherapy PET/CT, and 117 (89.3%) patients were eligible for PET/CT analysis. The median time from the end of treatment to PET/CT scan was 94 d (range, 52–139 d). Estimated 2-y PFS and LRC rates in the analysis subgroup were 91.3% (95% CI, 84.6, 95.8%) and 93.8% (95% CI, 87.6, 97.5%), respectively. Posttreatment scans were negative for residual tumor for 115 patients (98.3%) and positive for 2 patients (1.7%). NPV for 2-y PFS was 92.0% (90% lower confidence bound [LCB] 87.7%; P = 0.30) and for LRC was 94.5% (90% LCB 90.6%; P = 0.07). Conclusion: In the context of deintensification with reduced-dose radiation, the NPV of a 12- to 14-wk posttherapy PET/CT for 2-y LRC is estimated to be >90%, similar to that reported for patients receiving standard chemoradiation. However, there is insufficient evidence to conclude that the NPV is >90% for PFS.

本研究的目的是确定 p16 阳性患者治疗后 12 至 14 周 PET/CT 对 2 年无进展生存期 (PFS) 和局部区域控制 (LRC) 的阴性预测值 (NPV)局部晚期口咽癌（LA-OPC）。该研究是 NRG-HN002 的次要终点，这是一项针对 p16 阳性 LA-OPC、T1-T2、N1-N2b 或 T3、N0-N2b 期和吸烟≤10 包的非比较 II 期试验。患者以 1:1 的比例随机接受减剂量调强放疗 (IMRT)，联合或不联合顺铂。方法：集中审查 PET/CT 扫描。使用 5 点顺序量表（霍普金斯标准）对原发部位、右颈部和左颈部的肿瘤反应进行评估。然后将总分分为阴性、阳性或不确定。所有 3 个评估点均得分为负的患者的总体得分为负。假设为治疗后 2 年 PFS 和 LRC 的 NPV ≤ 90% 与 >90%（单边P值，0.10）。结果：共有 316 名患者入组，其中 306 名患者被随机分配且符合条件。其中，131 名 (42.8%) 患者同意接受治疗后 PET/CT，117 名 (89.3%) 患者符合 PET/CT 分析的条件。从治疗结束到 PET/CT 扫描的中位时间为 94 天（范围为 52-139 天）。分析亚组的估计 2 年 PFS 和 LRC 率分别为 91.3% (95% CI, 84.6, 95.8%) 和 93.8% (95% CI, 87.6, 97.5%)。治疗后扫描结果显示，115 名患者（98.3%）残留肿瘤呈阴性，2 名患者（1.7%）残留肿瘤呈阳性。 2 年 PFS 的 NPV 为 92.0%（90% 置信下限 [LCB] 87.7%； P = 0.30），LRC 的 NPV 为 94.5%（90% LCB 90.6%； P = 0.07）。 结论：在减少辐射剂量的去强化背景下，2 年 LRC 治疗后 12 至 14 周 PET/CT 的 NPV 估计 >90%，与接受标准放化疗患者的报告相似。然而，没有足够的证据得出 PFS 的 NPV > 90% 的结论。