Prospective study of fluorodeoxyglucose-positron emission tomography imaging of lymph node basins in melanoma patients undergoing sentinel node biopsy

Purpose: To prospectively compare positron emission tomography (PET) imagin g of regional lymph node basins to sentinel node biopsy (SNB) in patients w ith American Joint Committee on Cancer (AJCC) stage I, II, and III melanoma localized to the skin. Methods: Patients with cutaneous melanoma with Breslow's depth greater than 1 mm (AJCC T2-4N0M0) or localized regional cutaneous recurrence (TxN2bM0) underwent whole body imaging of glucose metabolism with fluorodeoxyglucose (FDG) PET followed by SNB, PET scans were interpreted in a blinded fashion and compared with histologic analyses of SNB specimens and clinical follow- up examination. Nodal tumor volumes were estimated. Results: Eighty-nine lymph node basins were evaluated by FDG-PET and SNB in 70 assessable patients. Eighteen patients (25.7%) held lymph node metastas es at the time of FDG-PET imaging: 17 proved by SNB (24.3%) and one by foll ow-up examination (1.4%). Median tumor volume in positive sentinel node bas ins was 4.3 mm(3) (range, 0.07 to 523 mm(3)). Sensitivity of SNB for detect ion of occult regional lymph node metastases was 94.4%, specificity war 100 %, positive predictive value (PPV) was 100%, and negative predictive value (NPV) was 98.6%. Sensitivity of FDG-PET was 16.7%, specificity was 95.8%, P PV was 50%, and NPV was 81.9%. At a median follow-up duration of 16.6 month s, seven patients (10%) developed recurrent dir ease. PET predicted one rec urrence (14.3%) in a node basin missed by SNB. Conclusion: FDG-PET is an insensitive indicator of occult regional lymph no de metastases in patients with melanoma because of the minute tumor volumes in this population. FDG-PET does not have a primary role for staging regio nal nodes in patients with clinically localized melanoma, J Clin Oncol 17:1 508-1515. (C) 1999 by American Society of Clinical Oncology.