One of the major side effects of chemotherapy in cancer treatment is that it can enhance tumor metastasis because it inhibits natural killer (NK) cell activity.
This study aimed to examine whether millimeter electromagnetic waves (
MMWs) radiation (42.2 GHz) can inhibit tumor metastasis enhanced by the anticancer drug cyclophosphamide (CPA).
The latest model of mmWs can work with three probes simultaneously. Peak SAR and incident power density were measured to be 730 +/- 100 W/kg and 36.5 +/- 5 mW/cm(2), respectively.
Tumor metastasis was evaluated in C57BL/6 mice, a commonly used experimental mouse model for metastatic melanoma. The animals were divided into 5 groups of 10 animals each.
The first group did not receive any treatment. The second group was irradiated with MMWs in the nose for 30 minutes. The third group served as a sham control for the second group. The fourth group was given CPA (150 mg/kg body weight, intraperitoneal injection) before irradiation. Group 5 served as a sham control for group 4.
On day 2, all animals were injected via the tail vein with B16F10 melanoma cells, a tumor cell line homologous to C57BL/6 mice. Lung tumor colonies were counted 2 weeks after inoculation. CPA led to a significant enhancement of tumor metastasis (fivefold), which was significantly reduced when animals treated with CPA were irradiated with MMW.
MMW therapy also increased NK cell activity that was suppressed by CPA, suggesting that MMW reduced tumor metastasis by activating NK cells.
