Background. Due to the advanced oncological treatments of cancer, an overall increase in cancer incidence, and better diagnostic tools, the incidence of brain metastases is on the rise. This review addresses the current treatment options for patients with multiple brain metastases, presenting electrochemotherapy (ECT) as one of the new experimental treatments for this group of patients.Conclusions. Neurosurgery, stereotactic surgery, and whole-brain radiotherapy are the evidence-based treatments that can be applied for patients with multiple brain metastases. Treatment with chemotherapy and molecularly targeted agents may also be warranted. Several experimental treatments are emerging, one of which is ECT, an effective cancer treatment comprising electric pulses given by electrodes in the tumor tissue, causing electroporation of the cell membrane, and thereby augmenting uptake and the cytotoxicity of the chemotherapeutic drug bleomycin by 300 times. Preclinical data are promising and the first patient has been treated in an ongoing clinical trial for patients with brain metastases. Perspectives for ECT in the brain include treatment of primary and secondary brain tumors as well as soft tissue metastases elsewhere.

Bleomycin has been used in the treatment of brain tumors for over 30 years. Currently, we are evaluating electrochemotherapy (the use of electric pulses to enhance uptake of bleomycin) for patients with secondary brain tumors. We, therefore, reviewed the literature with specific reference to the tolerability and toxicity of bleomycin. Using the keywords 'brain' and 'bleomycin', a database search without date restriction was performed and over 500 articles were found. Twenty-five articles were used for this study based on relevance determined by: (i) clinical studies, (ii) use of bleomycin, and (iii) direct injection into brain tissue or cysts. There were two main indications for the use of bleomycin directly into the brain: (i) cystic tumors in the form of craniopharyngiomas and (ii) solid brain tumors such as glioblastomas and astrocytomas. The most frequent adverse effects reported were transient fever, headaches, nausea and vomiting, lethargy, and peritumoral edema. Out of 189 patients treated from 1973 to 2007, only five patients (3%) had severe and six patients (3%) had moderate adverse effects. One death was directly related to this treatment, where very high doses were used. Two patients developed loss of vision and two patients had hearing loss because of the treatment. All cases with severe and moderate adverse effects except one were patients with craniopharyngiomas and probably because of tumor localization in the deep brain. In conclusion, bleomycin injection into the brain has been fairly well tolerated at doses much higher than that used in electrochemotherapy.