Notwithstanding the fact that there is some improvement for an earlier detection of patients with lung cancer, the majority of them still present with a late-stage disease at the time of diagnosis. Next to the most frequently used factors affecting the prognosis of lung cancer patients (stage, performance and age) the recent application of biomarkers obtained by liquid profiling gained more acceptance. In our study we aimed to answer these questions: i) is the quantification of free-circulating methylated PTGER4 and SHOX2 plasma DNA an useful method for the therapy monitoring and is this also possible for patients treated with different therapy regimens?, and ii) is this approach possible when blood drawing tubes are used which allow for a delayed processing of blood samples? Baseline values for mPTGER4 and mSHOX2 do not allow for a clear discrimination between different response groups. In contrast the combination of the methylation values for both genes show a clear difference between responders vs non-responders at the time of re-staging. Additionally, blood drawing into tubes stabilizing the sample give researchers more flexibility.