Early Treatment ctDNA Dynamics to Predict Response to Chemotherapy

This is a study that aims to understand whether a blood test measuring tumor DNA circulating in the bloodstream (circulating tumor DNA; ctDNA) shows a similar response as observed by a follow-up CT scan. To study this question, ctDNA will be measured at the same times as CT scans (just before the start of treatment, as well as 2 months after), and the response measured by the ctDNA change will be compared to the response seen on the changes between the CT scans. The goal is to make sure that ctDNA response correlates well with CT scan response measurement.