One of the major side effects of chemotherapy in cancer treatment is that it can enhance tumor metastasis due to suppression of natural killer cell activity.
Cyclophosphamide (150 mg/kg body weight) was administered before irradiation. All mice were injected with B16F10 melanoma cells, a tumor cell line syngeneic to C57BL/6 mice. Tumor colonies in lungs were counted 2 weeks following inoculation.
Animals were divided into 5 groups of 10 animals each. First group was not given any treatment, second group was exposed to MMW, third group served as sham control for group 2, fourth group was given 150 mg/kg CPA (cyclophosphamide) before exposure and the fifth group served as sham control for group 4.
|Exposure duration||continuous for 30 min|
|Modulation frequency||60 Hz|
|Modulation depth||100 %|
|Setup||The central part of the horn was positioned 5 mm from the nose of the anesthetized animal.|
Cyclophosphamide caused a marked enhancement in tumor metastases (fivefold), which was significantly reduced when cyclophosphamide-treated mice were irradiated with millimeter waves. Millimeter waves also increased natural killer cell activity suppressed by cyclophosphamide, suggesting that a reduction in tumor metastasis by millimeter waves is mediated through activation of natural killer cells.