Methods:The measurements were taken before and after treatment for comparison purposes. The study population comprised 17/29 patients with MCRC, undergoing PET/CT scanning prior to treatment. We were able to perform a follow up PET/CT examination three months after onset of therapy in 15/17 patients.Patients were instructed to fast for at least 6h before an injection of 18F-FDG(5 MBq/kg)(GeminiPET/CTsystem). Images were reconstructed using the maximum-likelihood 3-dimensional algorithm according to standard clinical protocol: 2 iterations,relaxation parameter of 0.05,5-mm,3-dimensional gaussian postfiltering, a4·4·4mm-voxel grid sampling, and attenuation correction based on a low-dose CT scan.All images were visually interpreted by consensus between two experienced nuclear physicians and standardized uptake values(SUVmax) were calculated from the image data.
Results:There were significant changes prior to treatment and three months later for sTRAIL(p=0.0080) and CXCL8(p=0.0001).Generally, sTRAIL values were increasing during therapy, while a decrease was observed for CXCL8.Correlation analysis was applied to the data and revealed significant correlations for the SUVmax in the primary tumor prior to treatment and CXCL8 prior to therapy(p=0.0303).Furthermore, significant correlations were observed for the SUVmax and sTRAIL(p=0.0237) as well as CXCL8(p=0.0002) three months after treatment initiation.CXCL8 prior to treatment was also correlated with the SUV three months after onset of treatment(p=0.0072).A significant correlation was noted for one combination of two variables, the SUVmax in the metastases and CXCL8 prior to treatment(p=0.0175).These results are supported when we group the SUVmax in the metastases following treatment into two groups with SUVmax<5 and SUVmax>5. There is a significant difference for both groups regarding overall survival, with a lower survival associated with SUVmaxs exceeding .
Conclusions:This study provides evidence that proteomics patterns of sTRAIL and CXCL8 predict tumor response und survival in MCRC patients treated with bevacizumab and within a high concordance of 18-FDG-PET/CT findings.The high correlation of CXCL8 and FDG uptake in metastases prior to treatment with survival direct to a promising approach to individualize treatment of patients.