Total body metabolic tumor response in ALK-positive non-small cell lung cancer treated with crizotinib.

e19062 Background: In ALK-positive advanced NSCLC, crizotinib has a high response rate and effectively increases quality of life and progression-free survival. CT measurement of the tumor and RECIST evaluation may not reflect the actual tumor load changes. Therefore we explored whether 18F-FDG measured metabolic change per voxel in the primary tumor and largest metastatic sites during ALK inhibition is a more accurate measurement for tumor changes. Methods: 18F-FDG PET/CT was performed prior to and after 6 weeks of crizotinib treatment. Volumes of interest were drawn on the baseline scans of primary tumor and the 14 largest measurable metastases using the IMALYTICS research workstation. Using the elastix toolbox, scans performed after 6 weeks were non-rigidly aligned to the baseline scan in order to generate a target’ scan for voxel-by-voxel analysis. The differences in SUV between baseline and target’ were calculated. The percentage of the tumor of which the voxels exceeded the previously calculated refe...