Predictive value of pre-treatment apparent diffusion coefficient (ADC) in radio-chemiotherapy treated head and neck squamous cell carcinoma

Objective: This study aimed at evaluating the role of “baseline” apparent diffusion coefficent (ADC), in patients affected by head and neck cancer treated with radio-chemotherapy, as a potential marker of response to therapy. Methods: Fifty-seven patients underwent pretreatment ADC maps. Minimum, maximum, and medium ADC were computed. Age, dose, treatment time, and ADC values were compared between the two groups (Group 1: local control; Group 2: relapse/persistence of disease) using the Student t test two-tailed unpaired. Two-tailed Fischer exact test was used to compare T stage, N stage, grading and type of treatment between two groups. We have analyzed the receiver operating characteristic (ROC) of statistically significant variables. Results: In patients with local control, values of pre-treatment medium and minimum ADC were lower than ADC values of patients with persistent or recurrent disease, with values, respectively, of 0.83 ± 0.02 × 10^–3 mm²/s and 0.59 ± 0.02 × 10^–3 mm²/s (vs 0.94 ± 0.05 × 10^–3 mm²/s and 0.70 ± 0.05 × 10^–3 mm²/s). ROC curve analysis displayed statistical significance as regarding the medium ADC value, showing a sensitivity of 50% and a specificity of 84.8%. ROC analysis of the values minimum ADC showed a sensitivity of 42.9% and specificity of 87.9%. Conclusion: The value of the ADC pre-treatment of patients with local control of the disease is lower than that of patients with persistent disease or recurrence.