Diagnostic performance of FDG PET/CT to detect subclinical HNSCC recurrence 6 months after the end of treatment.

ABSTRACT

PURPOSE: Posttreatment follow-up for the recurrence of head and neck squamous cell carcinoma (HNSCC) is a diagnostic challenge. Tissue distortion from radiation and surgery can obscure early detection of recurrence by conventional follow-up approaches such as physical examination or conventional imaging. Fluorodeoxyglucose (FDG) positron emission tomography (PET)/CT is widely validated for the diagnosis of suspected recurrence. Moreover, we have shown in a previous prospective study the high effectiveness of FDG PET/CT in the assessment of subclinical recurrence 12 months after treatment. The aim of this prospective study was to evaluate the effectiveness of an earlier FDG PET/CT, at 6 months after the end of treatment. METHODS: All patients treated for histologically proven HNSCC from April 2009 to May 2012 at the University Hospital of Brest who did not show any findings suggestive of recurrence at 6 months of their usual follow-up underwent an FDG PET/CT examination. FDG PET/CT findings were correlated with histopathology or imaging follow-up. RESULTS: The study included 116 patients. FDG PET/CT examinations were performed within a mean period ± SD of 5.6 ± 1.8 months after treatment. FDG PET/CT examinations exhibited abnormal FDG uptake in 34 patients and found no suspected recurrence in 82 cases. Of these 82 FDG PET/CT considered as negative, only 1 had a recurrence. Among the 34 positive FDG PET/CT, 22 relapsed whereas 12 did not show evidence of recurrence. The sensitivity and specificity of FDG PET/CT in this study for the diagnosis of occult HNSCC recurrence were 96 (22/23) and 87 % (81/93), respectively. The positive predictive value was 65 % (22/34). The negative predictive value was 99 % (81/82). The overall accuracy was 89 % (103/116). Of the 116 patients, FDG PET/CT highlighted 22 (19 %) subclinical recurrences. CONCLUSION: Our study showed the high effectiveness of FDG PET/CT in the assessment of subclinical HNSCC recurrence 6 months after completion of treatment. These results confirmed that FDG PET/CT is more accurate than conventional follow-up physical examination alone in the assessment of recurrence after previous curative treatment for HNSCC, as we previously demonstrated in patients clinically asymptomatic at 12 months.