Tumour assessment in advanced melanoma: value of FDG-PET/CT in patients with elevated serum S-100B.
OBJECTIVE
To evaluate the usefulness of PET/CT in melanoma patients with an elevated serum S-100B tumour marker level.


METHODS
Out of 165 consecutive high-risk melanoma patients referred for PET/CT imaging, 47 had elevated (>0.2 microg/l) S-100B serum levels and a contemporaneous 18F-FDG PET/CT scan. PET/CT scans were evaluated for the presence of metastases. To produce a composite reference standard, we used cytological, histological, MRI and PET/CT follow-up findings as well as clinical and S-100B follow-up.


RESULTS
Among the 47 patients with increased S-100B levels, PET/CT correctly identified metastases in 38 (30 distant metastases and eight lymph node metastases). In one patient with cervical lymph node metastases, PET/CT was negative. Eight patients had no metastases and PET/CT correctly excluded metastases in all of them. Overall sensitivity for metastases was 97% (38/39), specificity 100% (8/8) and accuracy 98% (46/47). S-100B was significantly higher in patients with distant metastases (mean 1.93 microg/l, range 0.3-14.3 microg/l) than in patients with lymph node metastases (mean 0.49 microg/l, range 0.3-1.6 microg/l, p=0.003) or patients without metastases (mean 0.625 microg/l, range 0.3-2.6 microg/l, p=0.007). However, 6 of 14 patients with a tumour marker level of 0.3 microg/l had no metastases.


CONCLUSIONS
In melanoma patients with elevated S-100B tumour marker levels, FDG-PET/CT accurately identifies lymph node or distant metastases and reliably excludes metastases. Because of the significant number of false positive S-100B tumour marker determinations (17%), we recommend repetition of tumour marker measurements if elevated S-100B levels occur before extensive imaging is used.
Strobel
Klaus
K
Division of Nuclear Medicine, Department of Medical Radiology, University Hospital Zurich, Raemistrasse 100, 8091, Zurich, Switzerland. klaus.strobel@usz.ch
Skalsky
Jeannine
J
Kalff
Victor
V
Baumann
Katrin
K
Seifert
Burkhardt
B
Joller-Jemelka
Helen
H
Dummer
Reinhard
R
Steinert
Hans C
HC
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor; D005189:False Positive Reactions; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000494:pharmacology*; D006801:Humans; D008297:Male; D008545:Melanoma / Q000097:blood* / Q000175:diagnosis / Q000628:therapy*; D008875:Middle Aged; D009362:Neoplasm Metastasis; D049268:Positron-Emission Tomography / Q000379:methods*; D014057:Tomography, X-Ray Computed / Q000379:methods*; D051598:Whole Body Imaging
D014408:Biomarkers, Tumor; D019788:Fluorodeoxyglucose F18