The impact of direct laryngoscopy on PET/CT scan results in newly diagnosed head and neck cancer

Objective: Direct laryngoscopy (DL) with a biopsy, followed by positron emission tomography (PET) is an established staging protocol for newly-diagnosed head and neck squamous cell carcinoma (HNSCC). However, inflammation and trauma from the DL could lead to false-positive PET and computed tomography (CT) interpretations. Therefore, we sought to determine the rate of false-positive findings on staging PET/CT scans performed soon after DL.

Methodology: We reviewed all initial staging PET/CT scans performed at a tertiary care hospital over a one-year period for newly-diagnosed HNSCC. Index cases had PET/CT scans performed within two weeks after a DL. We selected controls with matched tumor locations that underwent PET/CT without a DL in the preceding two weeks.

Results: We identified 17 patients with newly-diagnosed HNSCC that underwent a PET/CT scan within 14 days after a DL and biopsy. Scans were performed an average of 6 days (Range:1 -13) after the procedure. False-positive PET scan interpretations were observed in 53% of index patients, compared to 18% of matched controls. The odds ratio for a false positive PET scan finding was 5.6 (p=0.028) for index patients compared to controls.

Conclusions: Performing a staging PET/CT shortly after a DL and biopsy can increase the rate of false-positive interpretations. Radiologists/nuclear medicine physicians and otolaryngologists should be aware of this possibility and communicate with each other to avoid misdiagnosis.