In a patient with node-positive limited-stage small cell lung cancer, how do you approach radiation in a patient whose small primary tumor resolves after one cycle of chemotherapy?  

In the case of imaging CR, I delineate CTVp based on pre-chemo volumes and apply PTV margin. If less than CR, I use post-chemo volumes to delineate GTVp and then utilize 4DCT to construct ITVp followed by appropriate CTV and PTV margins. Both approaches are consistent with ESTRO ACROP guidelines pub...