Stone cold normal.
The Study: This is an important question because we saw in the D’Cruz trial that omitting an elective neck dissection in early stage oral cavity cancer reduced overall survival. But a neck dissection isn't a walk in the park. In the ACRIN 6685 trial, just over 200 patients with at least one clinically N0 side of the neck underwent initial staging PET/CT prior to planned neck dissection. Despite the fact that they only needed a single negative side, over 80% were completely cN0. Positivity or negativity on PET was qualitatively called by the radiologist, but a separate analysis was also done later based on SUV. In line with the D’Cruz trial, the rate of occult node positivity was close to 30%. PET/CT was called positive in nearly half the clinically N0 necks, but only 44% of those PET(+) necks were pathologically positive. Among the PET(-) necks, 13% ended up being pathologically positive. When they looked for an optimal SUV cut-off, no clear threshold emerged. However, an SUV of <1.8 in a clinically node negative side of the neck had a >90% negative predictive value.
Bottom Line: PET/CT imaging of a clinically negative neck can be misleading in patients with head and neck cancer, but a really negative PET (with max SUV <1.8) could help avoid ipsilateral elective neck dissection (and radiation?). | Lowe, J Clin Oncol 2019