Effectiveness of an 18F-FDG-PET based strategy to optimize the diagnostic trajectory of suspected recurrent laryngeal carcinoma after radiotherapy: The RELAPS multicenter randomized trial

Purpose The purpose of this study is to evaluate the efficacy of 18F-FDG-PET as first-line diagnostic investigation, prior to performing a direct laryngoscopy with biopsy under general anesthesia, in patients suspected of recurrent laryngeal carcinoma after radiotherapy. Patients and methods 150 patients suspected of recurrent T2–4 laryngeal carcinoma at least two months after prior (chemo)radiotherapy with curative intent for resectable disease were randomized to direct laryngoscopy (CWU: conventional workup strategy) or to 18F-FDG-PET only followed by direct laryngoscopy if PET was assessed ‘positive’ or ‘equivocal’ (PWU: PET based workup strategy), to compare the effectiveness of these strategies. Primary endpoint was the number of indications for direct laryngoscopies classified as unnecessary based on absence of recurrence, both on direct laryngoscopy and on six month follow up. Safety endpoints comprised resectability of recurrent lesions and completeness of surgical margins following salvage laryngectomy. Results Intention-to-treat analyses were performed on all randomized patients (CWU: n = 74, PWU: n = 76). Tumor recurrence was similar in both groups: 45 patients (30%; 21 CWU, 24 PWU) within six months. In 53 patients in the CWU arm (72%, 95% CI: 60–81) unnecessary direct laryngoscopies were performed compared to 22 in the PWU arm (29%, 95% CI: 19–40) (p < 0·0001). The percentage of salvage laryngectomies (resectability) and positive surgical margins were similar between CWU and PWU (81%, 63% respectively, p = 0·17, and 29%, 7%, respectively, p = 0.20). The prevalence of the combination of local unresectability and positive margins is in the CWU group 24% and in the PWU group 8%. No difference (p = 0.32) in disease specific survival between both groups was found. Conclusion In patients with suspected laryngeal carcinoma after radiotherapy, PET as the first diagnostic procedure can reduce the need for direct laryngoscopy by more than 50% without jeopardizing quality of treatment