18F-FDG PET as a Routine Posttreatment Surveillance Tool in Oral and Oropharyngeal Squamous Cell Carcinoma: A Prospective Study

The purpose of this study was to evaluate the role and timing of serial F-18-FDG PET scans as routine surveillance for detecting early locoregional recurrence, distant metastases, and second primary tumors in patients treated for advanced squamous cell carcinoma (SCC) in the oral cavity or oropharynx during the first year after completion of their curative treatment. Methods: Forty-eight consecutive patients with SCC in the oral cavity or oropharynx were included after completing their initial therapy with curative intent. Prospective follow-up of the participants was 2-fold: regular follow-up (history and physical examination) and serial F-18-FDG PET scans. Patients underwent standard follow-up and F-18-FDG PET at 3, 6, 9, and 12 mo after initial treatment. Findings were validated by histopathology or 18 mo of clinical follow-up and imaging after initial treatment. Results: Incidence of recurrences and second primary tumors was 27% and 10%, respectively. F-18-FDG PET was significantly (P = 0.035) more often in agreement with the gold standard than was regular follow-up. F-18-FDG PET showed a sensitivity, specificity, positive predictive value, and negative predictive value of 100%, 43%, 51%, and 100%, respectively. For regular follow-up, these values were 0%, 60%, 0%, and 50%, respectively. F-18-FDG PET accounted for a change in diagnostics or treatment in 63% of the patients and regular follow-up in 25% of the patients. Sensitivity and specificity of F-18-FDG PET were both irrespective of timing of F-18-FDG PET. For the 3- and 6-mo posttherapy results combined, F-18-FDG PET detected malignancy in 16 of the 18 patients. Conclusion: F-18-FDG PET is a suitable routine posttreatment surveillance tool in oral and oropharyngeal SCC patients and detects malignancy before clinical suggestion by the regular follow-up arises. The best timing of a systematic F-18-FDG PET scan is between 3 and 6 mo after treatment.