RESUMO
BACKGROUND AND OBJECTIVES: Cryoablation has been recognized as a potential tool in the treatment of cancer. Beside its ability to cause local destruction of the primary tumor, cryoablation has been claimed to induce a systemic anti-tumor immune response. We compared cryoimmunologic responses between cryoablation and surgical excision in a murine model of squamous cell carcinoma (SCC). MATERIALS AND METHOD: Six-to 8-weeks-old female mice (total n=30) were used for this study. Tumors were established at the flank of C3H mice with the SCCVII cell line, which is an immunogenic murine SCC of spontaneous origin in the C3H/HeJ mice. The mice underwent surgical excision or cryoablation, when the tumors were between 0.3 and 0.6 cm in the largest dimension. Successfully treated mice were re-challenged with the murine bladder cancer cells, namely, SCCVII cell line or MBT-2 cells at the contralateral flank. One week later, secondary tumor growth was estimated. Spleens were harvested from the mice that had no tumor after re-challenge. Effector splenocytes were added to the target SCCVII cells prelabeled with 3H thymidine. Cytotoxicity was investigated by measuring 3H thymidine releases from target cells. RESULTS: After re-challenging the SCCVII cell line, tumors were developed in 33% (1/3) of the mice treated by surgical excision, compared to 0% (0/4) of mice treated by cryoablation. In the cytotoxicity assay, there were no significant differences between the excision and cryoablation group. CONCLUSION: These results suggest that the anti-tumor immunologic effect of cryoablation in the murine SCC model is not better than that of surgical excision.