Combining standardized uptake value of FDG-PET and apparent diffusion coefficient of DW-MRI improves risk stratification in head and neck squamous cell carcinoma.

Objectives: To assess the independent prognostic value of standardized uptake value (SUV) and apparent diffusion coefficient (ADC), separately and combined, in order to evaluate if the combination of these two variables allows further prognostic stratification of patients with head and neck squamous cell carcinomas (HNSCC).

Methods: Pretreatment SUV and ADC were calculated in 57 patients with HNSCC. Mean follow-up was 21.3 months. Semiquantitative analysis of primary tumours was performed using SUV, ADC, ADC and ADC. The prognostic value of SUV, ADC, ADC and ADC in predicting disease-free survival (DFS) was evaluated with log-rank test and Cox regression models.

Results: Patients with SUV ≥5.75 had an overall worse prognosis (p = 0.003). After adjusting for lymph node status and diameter, SUV and ADC were both significant predictors of DFS with hazard ratio (HR) = 10.37 (95 % CI 1.22-87.95) and 3.26 (95 % CI 1.20-8.85) for SUV ≥5.75 and ADC ≥0.58 × 10 mm/s, respectively. When the analysis was restricted to subjects with SUV ≥5.75, high ADC significantly predicted a worse prognosis, with adjusted HR = 3.11 (95 % CI 1.13-8.55).

Conclusions: The combination of SUV and ADC improves the prognostic role of the two separate parameters; patients with high SUV and high ADC are associated with a poor prognosis.

Key Points: • High SUV is a poor prognostic factor in HNSCC • High ADC is a poor prognostic factor in HNSCC • In patients with high SUV , high ADC identified those with worse prognosis.