Does FDG-PET/CT improve the detection of early subclinical recurrence 6 months after treatment of HNSCC?

Objectives Posttreatment surveillance for the recurrence of 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. We showed in a previous prospective study (Abgral et al. J Nucl Med. 2009) the high effectiveness of FDG-PET/CT in the assessment of subclinical HNSCC recurrence 12 months after a curative 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 the treatment, for detection of subclinical locoregional recurrences of HNSCC or distant metastases.

Methods Seventy-seven patients cured of HNSCC without any clinical evidence of recurrence were included. Whole-body FDG-PET/CT examination was performed within a mean period ± sd of 5.5 ± 1.9 months after the end of the treatment. The gold standard was histopathology or 6 months of imaging follow-up.

Results The 6 months whole-body FDG-PET/CT examinations exhibited abnormal FDG uptake in 25 patients and found no suspected results of recurrence in 52 cases. Out of these 52 FDG-PET/CT considered as negative, only 1 had a recurrence (FN). Among the 25 positive FDG-PET/CT, 18 relapsed whereas 7 did not show evidence of recurrence (FP). The sensitivity and specificity of FDG-PET/CT in this study for the diagnosis of occult HNSCC recurrence were 95% (18/19) and 88% (51/58), respectively. The positive predictive value was 72% (18/25). The negative predictive value was 98% (51/52). The overall accuracy was 90% (69/77). Out of the 77 patients, FDG-PET/CT highlighted 18 (23%) subclinical recurrence.

Conclusions As we shown at 12 months of the follow up, our results confirm the effectiveness of an early FDG-PET/CT evaluation in order to diagnose unsuspected recurrence even at 6 months of the end of the treatment.