Major depression has a high incidence in patients with cancer, but treatment guidelines for this vulnerable population are missing and antidepressants seem to be less effective than in patients not affected by cancer. We report the case of a patient with bronchial cancer with a single temporo-occipital brain metastasis that had been treated by radiotherapy (whole-brain radiation, 40 Gy, followed by a stereotactic radiotherapy, 15 Gy). The patient developed a major depressive episode and was successfully treated with electroconvulsive therapy without relevant adverse events. This case further underscores the safety and effectiveness of electroconvulsive therapy after radiotherapy of the brain and demonstrates a viable alternative for severely depressed patients with cancer who do not adequately respond to psychotherapy or pharmacotherapy alone.