The negative predictive value of FDG PET/CT staging in early oropharyngeal squamous cell carcinoma and implications to transoral robotic surgery patient selection.

Objectives: Our objective was to determine the negative predictive value (NPV) of preoperative FDG PET/CTfor detecting locoregional nodal disease. The aim was to help inform the decision-making process when identifying patients with early-stage OPSCC that would be suitable for transoral robotic surgery (TORS) as a single-modality treatment.

Materials And Methods: A retrospective cohort study was conducted of adults with primary stage cT1-2 OPSCC with up to one metastatic neck lymph node (cN0-1) planned for TORS. Patients with a preoperative PET/CT and who had undergone staging neck dissection (ND) were included. Clinical and pathological nodal staging was established based on PET/CT and ND, respectively. The primary outcome was the frequency of occult (not seen on PET/CT) nodal disease on ND.

Results: Eighty-eight patients were included (N = 88). The rate of occult nodal disease was 28.4 % (n = 25). The NPV of PET/CT in the clinically negative neck was 79 % and 66 % in cases with a single clinical node. Following staging ND, thetreatment plan changed in 27 % of cases overall, 7 % in cN0 and 36.7 % in cN1. Among these, 18 % met criteria for radiotherapy and 9 % for CRT. This represented a decrease in the number of ideal candidates for TORS as single-modality treatment from 88 to 64 (73 %).

Conclusions: PET/CT is a useful tool in the workup of patients for primary TORS. However, about one third of patients with early-stage OPSCC might benefit from adjuvant therapy not predicted by preoperative PET/CT. A staging ND helps confirm candidates for single-modality treatment with TORS.