Anticancer activity by magnetic fields: inhibition of metastatic spread and growth in a breast cancer model

The possibility that magnetic fields (MFs) induce anticancer activity in vivo has been investigated by using a highly metastatic human cancer model transplanted in immunoincompetent mice (CD-1, nu-nu). The nude mice, bearing a subcutaneous human breast tumor (MDA-MB-435), were exposed for 70 min daily, for six consecutive weeks, to modulated MF (static with a superimposition of extremely low-frequency fields at 50 Hz) having a time-average total intensity of 5.5 mT. A positive control group was treated with a chemotherapeutic agent (cyclophosphamide). Neither MF nor cyclophosphamide significantly reduced the total number of pulmonary metastases. Both treatments induced a significant inhibition on spread and growth of intermediate (10-100 cells) and large (>100 cells) lung metastases compared with the MF sham-treatment. The inhibition induced by the MF was significantly greater than that observed in mice treated with cyclophosphamide. Gross pathology at necroscopy, hematoclinical/hematological, and histological examination did not show any toxic or abnormal effects. These findings support a potential use of MF as an anticancer agent.