This application discloses an improved approach for delivering alternating electric fields (e.g., TTFields) at a therapeutically effective strength to a target region of the spinal anatomy. In some embodiments, first and second sets of electrode elements are positioned with their centroids adjacent to upper and lower portions of the person's spine, respectively. In other embodiments, a first set of electrode elements is positioned with its centroid on an upper surface of the person's head, and a second set of electrode elements is positioned with its centroid adjacent to the person's spine (e.g., below the L3 vertebrae). Applying an AC voltage between the first and second sets of electrode elements generates a generally vertical field in the target region at levels that are not achievable using other layouts for positioning the electrode elements on the subject's body. These configurations are particularly useful for preventing and/or treating metastases.
