Prospective Comparison of [18F] Fluorodeoxyglucose Positron Emission Tomography and Computed Tomography in Patients With Melanoma With Palpable Lymph Node Metastases: Diagnostic Accuracy and Impact on Treatment

Purpose Patients with melanoma with potentially resectable lymph node metastases require accurate staging to prevent unnecessary surgery. [F-18] Fluorodeoxyglucose (FDG) positron emission tomography (PET) is attractive for this because melanoma typically is FDG avid. The aim of this prospective multicenter study was to perform a head-to-head comparison of FDG-PET and computed tomography (CT) in staging of patients with melanoma with palpable lymph node metastases in terms of diagnostic accuracy and impact on treatment. Patients and Methods All consecutive patients with palpable, proven lymph node metastases of melanoma between mid 2003 and 2007 were prospectively included. The number/site of distant metastases detected with FDG-PET and CT were recorded. Histology/cytology or 6 months follow-up were the reference standard. Intended and performed treatment was recorded. Results Distant metastases were suspected by FDG-PET in 32% of the 251 patients and by CT in 29% (P = .26). Upstaging was correct in 27% by FDG-PET and in 24% by CT (P = .18). FDG-PET detected more metastatic sites (133 v 112, P = .03), detecting significantly more bone and subcutaneous metastases. Treatment changed in 19% of patients; in 79% as a result of both scans, in 17% exclusively by FDG-PET, and in 4% exclusively by CT. In 34 patients (14%), FDG-PET had an additional value over spiral CT, and in 23 patients (9%), CT had additional value over FDG-PET. Conclusion As a result of FDG-PET and CT, 27% of patients were upstaged, and treatment changed in one of five patients. FDG-PET and CT are equivalent in upstaging; however, FDG-PET detected more metastatic sites, especially bone and subcutaneous. FDG-PET and/or CT are indicated in the staging of patients with melanoma with palpable lymph node metastases.