RT Journal Article SR Electronic T1 18F-FDG PET/CT Prediction of Treatment Outcomes in Human Papillomavirus–Positive, Locally Advanced Oropharyngeal Cancer Patients Receiving Deintensified Therapy: Results from NRG-HN002 JF Journal of Nuclear Medicine JO J Nucl Med FD Society of Nuclear Medicine SP 362 OP 367 DO 10.2967/jnumed.122.264424 VO 64 IS 3 A1 Rathan M. Subramaniam A1 Lyudmila DeMora A1 Min Yao A1 Sue S. Yom A1 Maura Gillison A1 Jimmy J. Caudell A1 John Waldron A1 Ping Xia A1 Christine H. Chung A1 Minh Tam Truong A1 Michelle Echevarria A1 Jason W. Chan A1 Jessica L. Geiger A1 Loren Mell A1 Samantha Seaward A1 Wade L. Thorstad A1 Jonathan Jay Beitler A1 Khalil Sultanem A1 Diagjin Blakaj A1 Quynh-Thu Le YR 2023 UL http://jnm.snmjournals.org/content/64/3/362.abstract AB 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.