In this study, the therapeutic effect and the induced anti-tumor immunity through the alternating cooling and heating was investigated using 4T1 murine mammary carcinoma, a common model of human metastatic breast cancer. While fifteen of seventeen regular mice were cured, primary recurrence and metastasis caused death of all the nude mice within one month after the same treatment. Histological analyses showed that viable cells existed in the tumor debris after the treatment, indicating that the direct killing effect was not the only therapeutic mechanism. Further investigation found rejection of tumor upon re-challenge, and anti-tumor immune response was studied. Stronger cytotoxicity T-lymphocyte (CTL) and Th1 cytokines response as well as infiltration of immunocytes were observed in the treated mice in comparison to those after the surgical resection. The results showed that the alternating cooling and heat could stimulate anti-tumor immunologic response in vivo and the underlying mechanisms will be further investigated in the near future.

A new in-situ thermal physical method combining both cryosurgery and local hyperthermia was used to treat mice bearing 4T1 murine mammary carcinoma. The induced anti-tumor immune response was investigated. The cryo/heat treatment resulted in stimulation of CTL response and attraction of immunocytes into the tumor debris, which correlated well to the tumor rejection in re-implantation. The results suggested that alternated cooling and heating had synergistic effect and might be developed into an alternative modality for tumor therapy.