Chemotherapy response assessment in stage IV melanoma patients—comparison of 18F-FDG-PET/CT, CT, brain MRI, and tumormarker S-100B

Abstract

PURPOSE: This study aims to compare the use of 18F-FDG-PET/CT, CT, brain MRI, and tumormarker S-100B in chemotherapy response assessment of stage IV melanoma patients. METHODS: In 25 patients with stage IV melanoma, FDG-PET/CT and S-100B after 2-3 months (three cycles) of chemotherapy was compared with baseline PET/CT and baseline S-100B. Retrospectively, the response was correlated with the outcome. In patients with clinical suspicion for brain metastases, MRI or CCT was performed. RESULTS: There was agreement between FDG-PET/CT and CT regarding response to chemotherapy in all patients. There was a clear trend to a longer OS of PET/CT responders (n = 10) compared with PET/CT non-responders (n = 15; p = 0.072) with remarkably better 1-year OS of 80% compared to 40% (p = 0.048). There was a significant longer PFS of PET/CT responders compared with PET/CT non-responders (p = 0.002). S-100B was normal at baseline in eight of 22 patients where it was available. Chemotherapy response assessment with S-100B failed to show correlation with OS or PFS. Eleven patients developed brain metastases during treatment, first detected by PET/CT in two and by MRI or CCT in nine of 11 patients. Appearance of brain metastases was associated with a poor survival. CONCLUSIONS: 18F-FDG-PET/CT and CT alone are equally suitable for chemotherapy response assessment in melanoma patients and clearly superior to S-100B. PET/CT responders have better early survival, but this is shortlived due to late therapy failure-often with brain recurrence. Additional brain MRI for therapy response assessment in such high-risk patients is mandatory to detect brain metastases missed by PET/CT. Chemotherapy Response Assessment in MethodsIn 25 patients with stage IV melanoma FDG-PET/CT and S-100B after 2-3 months (3 cycles) of chemotherapy was compared with baseline PET/CT and baseline S-100B.Retrospectively, the response was correlated with the outcome. In patients with clinical suspicion for brain metastases MRI or CCT was performed. ResultsThere was agreement between FDG-PET/CT and CT regarding response to chemotherapy in all patients. There was a clear trend to a longer OS of PET/CTresponders (n=10) compared with PET/CT non-responders (n=15) (p=.072) with remarkably better 1-year OS of 80% compared to 40% (p=.048). There was a significant longer PFS of PET/CT-responders compared with PET/CT nonresponders (p=.002). S-100B was normal at baseline in 8 of 22 patients where it was available. Chemotherapy response assessment with S -100B failed to show correlation with OS or PFS. 11 patients developed brain metastases during treatment, first detected by PET/CT in 2 and by MRI or CCT in 9 of 11 patients.Appearance of brain metastases was associated with a poor survival.

Radioimmunotherapy of Experimental Human Metastatic Melanoma with Melanin-Binding Antibodies and in Combination with Dacarbazine

“…In patients with many different cancers including melanoma, the early response to chemotherapy correlates with the significant decrease in [ 18 F]FDG tumor uptake during PET due to an inability of dying or dead cells to actively take up glucose and predicts the overall response to therapy (20). Likewise, in tumor-bearing mice treated with chemotherapy, the decrease in [ 18 F]FDG tumor uptake in comparison with the baseline value was much less pronounced than in mice treated with RIT alone.…”

Assessment of Response to Therapy

“…There is a significantly longer progression-free survival of PET/CT responders compared with PET/CT nonresponders. As chemotherapy response assessment with serum S-100B tumor marker fails to show correlation with survival, 18F-FDG PET/CT may present a promising tool (Strobel et al 2008). Strobel et al also reached to the same conclusion.…”

Oncologic PET/MRI, Part 2: Bone Tumors, Soft-Tissue Tumors, Melanoma, and Lymphoma

“…Both 18 F-FDG PET/CT and MRI are sensitive to changes under local and systemic therapy. 18 F-FDG PET/CT has been shown to outperform the tumor marker S100 in the discrimination of responders from nonresponders in a study on stage IV melanoma patients (48). Responders to chemotherapy identified by 18 F-FDG PET/CT in a retrospectively performed evaluation have been proven to have a longer progression-free and overall survival than nonresponders (48).…”

“…18 F-FDG PET/CT has been shown to outperform the tumor marker S100 in the discrimination of responders from nonresponders in a study on stage IV melanoma patients (48). Responders to chemotherapy identified by 18 F-FDG PET/CT in a retrospectively performed evaluation have been proven to have a longer progression-free and overall survival than nonresponders (48). Experimental studies performed mainly ex vivo on melanoma xenografts reported that the amount of tumor cell necrosis and the oxygenation status of tumor cells could be assessed using nuclear MR spectroscopy (49).…”

“…Experimental studies performed mainly ex vivo on melanoma xenografts reported that the amount of tumor cell necrosis and the oxygenation status of tumor cells could be assessed using nuclear MR spectroscopy (49). More clinically relevant is the potential of MRI in restaging brain metastases, as these have been proven to be predictive of a poor prognosis (48). Data on the performance of integrated PET/MRI in melanoma restaging and response assessment are awaited but not available at present.…”