S-100B and FDG-PET/CT in therapy response assessment of melanoma patients.
OBJECTIVE
To compare the value of the tumor marker S-100B protein and fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) in patients treated for melanoma metastases.


METHODS
In 41 patients with proven melanoma metastases, S-100B measurements and FDG-PET/CT were performed before and after therapy. The change of S-100B levels (DeltaS-100B) was assessed. In all patients, therapy response was assessed with PET/CT using visual criteria and change of maximal standard uptake value (DeltaSUV(max.)) or total lesion glycolysis (DeltaTLG).


RESULTS
In 15 of 41 patients (37%), S-100B values were not suitable because they were normal before and after therapy. In 26 patients, S-100B was suitable for therapy response assessment. PET/CT was suitable for response assessment in all patients. Correlations between DeltaS-100B and DeltaTLG (r = 0.850, p < 0.001) and between DeltaS-100B and DeltaSUV(max.) (r = 0.818, p < 0.001) were both excellent. A complete agreement between S-100B and PET/CT response assessment was achieved in 22 of 26 patients. In 4 patients, therapy response differed between the S-100B and PET/CT findings, but subsequent S-100B measurements realigned the S-100B results with the later PET/CT findings.


CONCLUSIONS
In a third of our patients with metastases, the S-100B tumor marker was not suitable for therapy assessment. In these patients, imaging techniques remain necessary, and FDG-PET/CT can be used for response assessment.
Strobel
Klaus
K
Division of Nuclear Medicine, Department of Medical Radiology, University Hospital Zurich, Zurich, Switzerland. klaus.strobel@usz.ch
Skalsky
Jeannine
J
Steinert
Hans C
HC
Dummer
Reinhard
R
Hany
Thomas F
TF
Bhure
Ujwal
U
Seifert
Burkhardt
B
Pérez Lago
Marisol
M
Joller-Jemelka
Helen
H
Kalff
V
V
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000097:blood*; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008297:Male; D008545:Melanoma / Q000097:blood / Q000175:diagnosis* / Q000000981:diagnostic imaging; D008875:Middle Aged; D009414:Nerve Growth Factors / Q000097:blood*; D049268:Positron-Emission Tomography; D019275:Radiopharmaceuticals; D064568:S100 Calcium Binding Protein beta Subunit; D009418:S100 Proteins / Q000097:blood*; D012878:Skin Neoplasms / Q000097:blood / Q000175:diagnosis* / Q000000981:diagnostic imaging; D014057:Tomography, X-Ray Computed