[18F]FDG-PET/CT based response assessment of stage IV non-small cell lung cancer treated with paclitaxel-carboplatin-bevacizumab with or without nitroglycerin patches

Purpose
Nitroglycerin (NTG) is a vasodilatating drug, which increases tumor blood flow and consequently decreases hypoxia. Therefore, changes in [18F]fluorodeoxyglucose-positron emission tomography ([18F]FDG-PET) uptake pattern may occur. In this analysis, we investigated the feasibility of [18F]FDG-PET for response assessment to paclitaxel-carboplatin-bevacizumab (PCB) treatment with and without NTG patches. And we compared the [18F]FDG-PET response assessment to RECIST response assessment and survival.
Methods
A total of 223 stage IV non-small cell lung cancer (NSCLC) patients were included in a phase II study (NCT01171170) randomizing between PCB treatment with or without NTG patches. For 60 participating patients a baseline and a second [18F]FDG-PET/CT scan, performed between day 22-24 after the start of treatment, were available. Tumor response was defined as a 30% decrease in CT- and PET-parameters, and was compared to RECIST response at week 6. The predictive value of these assessments for progression free survival (PFS) and overall survival (OS) was assessed with and without NTG.
Results
A 30% decrease in SUVpeak assessment identified more patients as responders compared to a 30% decrease in CTdiameter assessment (73% vs. 18%), however, this was not correlated to OS (SUVpeak30 p=0.833; CTdiameter30 p=0.557). Changes in PET parameters between the baseline and the second scan were not significant different for the NTG group compared to the control group (p-value range 0.159 - 0.634). The CT (part of the [18F]FDG-PET/CT) based parameters showed a significant difference between the baseline and the second scan for the NTG group compared to the control group (CT diameter decrease of 7 ± 23% vs. 19 ± 14%, p=0.016, respectively).
Conclusions
The decrease in tumoral FDG uptake in advanced NSCLC patients treated with chemotherapy with and without NTG did not differ between both treatment arms. Early PET-based response assessment showed more tumor responders than CT-based response assessment (part of the [18F]FDG-PET/CT), this was not correlated to survival. This might be due to timing of the [18F]FDG-PET shortly after the bevacizumab infusion.