Clinical impact of PET/CT imaging after adjuvant therapy in patients with oral cavity squamous cell carcinoma

Purpose: This single-center retrospective study of prospectively collected data was aimed at comparing the clinical outcomes of positron emission tomography/computed tomography (PET/CT) for patients with oral cavity squamous cell carcinoma (OSCC) with symptomatic recurrences identified by PET/CT imaging following adjuvant therapy (Group A) versus those of cases with asymptomatic recurrences diagnosed through periodic post-adjuvant therapy PET/CT surveillance (Group B). We also sought to establish the priority of salvage therapy in the two study groups. Methods: We identified 111 patients with advanced resected OSCC who developed recurrences following adjuvant therapy (51 in Group A and 60 in Group B). Histopathology served as the gold standard for recurrent lesions. The impact of post-adjuvant therapy PET/CT surveillance was examined with Kaplan-Meier curves and Cox proportional hazards regression models. Results: The 2-year DSS and OS rates were marginally or significantly higher in Group B than in Group A (P = 0.073 and P = 0.025, respectively). Time-dependent ROC curve analysis demonstrated that the optimal cutoff values for time to positive PET/CT findings in relation to OS were 12 months for Group A and 9 months for Group B, respectively. Independent risk factors identified in multivariate analyses were used to devise two prognostic scoring systems for 2-year DSS and OS in each study group (all P < 0.001). Conclusions: Scheduled periodic PET/CT surveillance is a valuable tool for early detection of recurrent lesion(s) in asymptomatic OSCC patients who bear risk factors for disease recurrence. The presence of clinical symptoms and a short time to positive PET/CT findings were adverse prognostic factors for clinical outcome in patients with advanced OSCC. The priority of salvage therapy is discussed in each patient subgroup according to the devised prognostic scoring systems.