Objective: To evaluate the anti-tumor effect of combined cryosurgery and immunotherapy in mice.
Methods: C57BL/6 mice bearing B16 melanoma were randomly divided into 3 groups: (1) peri-cryosurgical immunotherapy group, (2) cryosurgery group, (3) immunotherapy group and (4) saline group.
Results: The tumor size on day 35 was 0.4 cm3 in group 1, 1.1 in group 2, 1.9 in group 3, and 3.9 in group 4 of mice. The survival period was 71, 62, 53 and 46 days, respectively. None in group 3 and 4 was cured, while 14% of mice in group 2 and 50% in group 1 were tumor tree. In tumor-free mice, no tumor cell in the primary tumor sites was found by light and electron microscopy 3 months later.
Conclusion: The combined use of cryosurgery and immunotherapy is curative in 50% of mice bearing established B16 melanoma.