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. [(18)F]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.