13. image-guided concurrent chemoablation-and cryoablation for lung cancer: A preliminary clinical investigation

We report on the feasibility of CT guided percutaneous concurrent interstitial chemoablation-and-conformal cryoablation therapy for inoperable lung tumors compared to conformal cryoablation only. The goal is to control and improve the cryo-kill zone at the margin of the target lesion with the intra-operative addition of cytotoxic free drug(s). The combination method is performed on selected patients as follows: Under CT guidance, depending on the size and location of tumors two or more cryoneedles are inserted into target along with injection needle. Injection needle is centrally located and cryoneedles shall freeze up to the tumor margins as in our conventional procedure (conformal cryoablation1). The drug dosage is calculated on the tumor volume. Solution or emulsion of cytotoxic and/or chemical drug mixture with an imaging hydrosoluble (Hs) or liposoluble (Ls) contrast agent is prepared at time of intervention and injected a few seconds before conformal cryoablation. Intra lesional drug distribution and cryoablation is assessed by sequential CT for proper tumor drug filling and for adequate tumor freezing (ice coverage). Post operative CT is performed to assess the changes in tumor density, dimension and the effectiveness of cryo-chemoablation. Results show that drug injection immediately preceding cryoablation is always doable with easy visualization of contrast agent distribution regardless of the associated drug characteristics. Ls contrast fills the tumor site better than Hs contrast but somehow hinders perfect visualization of ice ball margins. Ls contrast is trapped within tumor conversely to Hs contrast that disappears after a few minutes. Both contrast agents are not displaced by tumor freezing. Peripheral lung parenchymal reaction seems grander with drug Hs contrast mixture than with drug Ls contrast mixture. Conclusion: per cutaneous CT guided concurrent interstitial chemoablation-and-cryoablation for lung tumors is feasible and allows controllable drug localization in this short series of patients. It does not add complexity or safety risks to the conformal cryoablation technique. The search for and demonstration by CT imaging of drug distribution and/or prolonged retention at cryotreated tumor margins needs improvements in the drug-to-contrast agent formulation, and timing of drug/contrast-to-cryo administration.