- You will have an x-ray, CT scan, MRI, and/or PET/CT scan to check the status of the disease. Blood (about 1 tablespoon) will be drawn for tumor marker testing. After at least 6 months of taking the study drugs, you may have CT, MRI, and/or PET/CT scans and blood drawn every 3 cycles (every 12 weeks) if the study doctor thinks it is needed.