Multicenter Trial of [18F]fluorodeoxyglucose Positron Emission Tomography/Computed Tomography Staging of Head and Neck Cancer and Negative Predictive Value and Surgical Impact in the N0 Neck: Results From ACRIN 6685

Abstract

Purpose: The objective of this study was to determine the negative predictive value (NPV) of positron emission tomography (PET)/computed tomography (CT) for the clinically N0 neck on the basis of neck dissection.

Methods: Participants with newly diagnosed, first-time, head and neck squamous cell carcinoma (HNSCC) and at least one clinically N0 neck side for which dissection was planned were included. A total of 287 participants were prospectively enrolled from 23 American College of Radiology Imaging Network-qualified institutions. PET/CT was compared with findings at neck dissection.

Results: PET/CT scans and pathology findings were available for 270 N0 neck sides from 212 participants. For visual assessment, the NPV specific to the clinical-N0 sides was 0.868 (95% CI, 0.803 to 0.925). For dichotomized maximum standardized uptake value, the NPVs specific to the nodal basins were 0.940 (95% CI, 0.928 to 0.952) and 0.937 (95% CI, 0.925 to 0.949) at prespecified cutoffs of 2.5 and 3.5, respectively. The optimal cutoff maximum standardized uptake value was determined to be 1.8, with an NPV of 0.942 (95% CI, 0.930 to 0.953). The PET/CT-informed surgical treatment plan was changed in 51 of 237 participants (22%) compared with the PET/CT-blinded surgical plan. In 34 participants (14%), this led to planned dissection of additional nodal levels. In 12 participants (5%), this led to fewer planned dissected nodal levels. Negative PET/CT scans in N0 necks was true negative in 87% and false negative in 13%.

Conclusion: [¹⁸F]fluorodeoxyglucose-PET/CT has high NPV for the N0 neck in T2 to T4 HNSCC. The surgical treatment plans on the basis of PET/CT findings may be changed in approximately 22% of this group. These findings suggest that [¹⁸F]fluorodeoxyglucose-PET/CT may assist the clinician in deciding on the best therapy for the clinically N0 neck in HNSCC. Well-designed clinical trials should be performed to test the outcome of omitting neck dissection by using PET/CT.

FIG 1.

Standards for the Reporting of Diagnostic Accuracy Studies diagram: neck-level portion. Numbers of N0 necks evaluated are shown. The total number of N0 necks (*) with surgery planned is the number of sides of necks that were N0 and had surgery planned pre–positron emission tomography (PET) in eligible participants with PET examinations available for review (see Data Supplement for participant-level portion).

FIG 2.

Participant examples. Computed tomography (top) and positron emission tomography (bottom) images of four participants are shown. True-positive (TP), true-negative (TN), and false-negative (FN) examples are shown. One example (C) was TP by maximum standardized uptake value (SUVmax) and FN by visual reading. Nodal descriptions by level and size are shown (lymph nodes or region indicated on images; orange arrows on computed tomography and blue arrows on positron emission tomography). Pathology findings and SUVmax values are shown. SCC, squamous cell cancer.