Can "early" and "late"18F-FDG PET-CT be used as prognostic factors for the clinical outcome of patients with locally advanced head and neck cancer treated with radio-chemotherapy?

Abstract

To evaluate the prognostic value of "early" and "late" Fluorine-18-Fluorodeoxyglucose ((18)F-FDG) positron emission tomography-computed tomography (PET-CT) in patients with head and neck squamous cell carcinoma (HNSCC) treated with radio-chemotherapy (RTCT). Twenty-six patients treated with RTCT for HNSCC were included. All patients underwent (18)F-FDG PET-CT at baseline ("staging" PET-CT), after 2 weeks of treatment ("early" PET-CT) and 8-12 weeks after treatment ("late" PET-CT). Changes in FDG uptake in the primary tumor (T) and lymph nodes (N) were correlated with local and regional control, respectively; overall metabolic response was correlated with relapse free survival (RFS) and disease specific survival (DSS). After a median follow-up of 29.2 months, 19/26 patients were living and 17/19 had no evidence of disease. When comparing "staging", "early" and "late" PET results, a significant decrease of FDG SUV(max) in T and N was documented. When correlating changes in FDG uptake in T and N with local and regional control, a statistically significant correlation only with the "late" reduction was found. Statistical analysis failed to demonstrate any correlation between the "early" metabolic response and the patient clinical outcome while the "late" metabolic response revealed a strong correlation with RFS (p = 0.01) and DSS (p = 0.009). In patients with HNSCC, PET-CT performed after RTCT predicts the clinical outcome, since it strongly correlates with RFS and DSS. On the other hand, the predictive role of "early" metabolic response was not confirmed by this study.