Abstract
Objective: To determine the negative predictive value (NPV) of a 12-14 week post-treatment PET/CT for 2-year 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 non-comparative phase II trial in p16-positive LA-OPC, stage T1-T2, N1-N2b or T3, N0-N2b (AJCC, 7th ed.) and ≤ 10 pack-year smoking. Patients were randomized in a 1:1 ratio to reduced-dose 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 carried out 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 three evaluation sites were given an overall score of ‘Negative.’ The hypotheses were NPV for PFS and LRC at two years post-treatment ≤ 90% vs >90% (1-sided alpha 0.10). Results: There were 316 patients enrolled, of whom 306 were randomized and eligible. Of these, 131 (42.8%) patients consented to a post-therapy 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 days (range 52-139). Estimated 2-year PFS and LRC rates in the analysis subgroup were 91.3% (95% confidence interval CI [84.6, 95.8%]) and 93.8% (95% CI [87.6, 97.5%]), respectively. Post-treatment scans were negative for residual tumor for 115 patients (98.3%) and positive for two patients (1.7%). NPV for 2-year 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 12-14 week post-therapy PET/CT for 2-year 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.
- Oncology: Head and neck
- PET/CT
- Radiopharmaceuticals
- NRG-HN002
- PET/CT negative predictive value
- p16-positive oropharyngeal cancer
- Copyright © 2022 by the Society of Nuclear Medicine and Molecular Imaging, Inc.