Antineoplastic effect of laser immunotherapy in mice with multiple cutaneous squamous cell carcinoma

Abstract

Objective To evaluate the antineoplastic effect of laser immunotherapy in mice with multiple cutaneous squamous cell carcinoma (CSCC) . Methods Normal immunocompetent hairless SKH-1 mice were consecutively irradiated by ultraviolet rays to establish mouse models of multiple CSCC. Then, 20 CSCC-bearing mice were randomly and equally divided into 4 groups: laser group irradiated with an 808-nm near-infrared laser (1 W/cm2, 10 minutes) once every two weeks for a total of 3 sessions, laser immunotherapy group irradiated with an 808-nm near-infrared laser as above and topically treated with imiquimod cream once a day for 3 days before and after each session of irradiation, imiquimod group treated with imiquimod cream as in the laser immunotherapy group, and control group receiving no treatment. The volume of tumors was calculated, and their morphology as well as the survival of mice were observed after the treatment. The t test and Mantel-Cox log-rank test were used to compare the volume of tumors on the dorsum and survival rates of mice, respectively, on days 27 and 60 after the start of treatment. Another 12 CSCC-bearing mice were randomly and equally divided into the 4 groups mentioned above, and tumor tissues were resected from these mice for histopathological examination on day 5 after the first treatment. Results On day 27, the volume of tumors significantly increased in the control group and imiquimod group (both P 0.05) . Moreover, the volume of tumors in the control group was slightly larger than that in the imiquimod group (P > 0.05) , but significantly larger than that in the laser group and laser immunotherapy group (both P 0.05) , significantly longer in the laser group and laser immunotherapy group compared with the control group (both P 0.05) . Histopathological examination showed that 5-day topical application of imiquimod cream did not cause death of tumor cells, but numerous tumor cells died in the laser group and laser immunotherapy group. Multiple inflammatory cells were observed around the tumors, and the number of the inflammatory cells was obviously larger in both the laser group and laser immunotherapy group, especially in the latter group, compared with the control group. Conclusion Laser immunotherapy is a new effective and safe treatment for CSCC in mice, and has potential value especially in the treatment of multiple or metastatic CSCC. Key words: Neoplasms, squamous cell; Laser; Immunity; Mice