Two Elderly Men with Myasthenia Gravis during Androgen Deprivation Therapy for Prostate Cancer.

Myasthenia gravis (MG) development is female-dominant in younger patients and male-dominant in older patients. The reason for the sex-ratio inversion in elderly MG patients remains unclear. One possible explanation is the decrease in androgen secretion that occurs with aging, as androgen has an immunosuppressive function. We experienced two elderly men who developed MG after initiating androgen deprivation therapy (ADT) for treatment of prostate cancer and whose symptoms were ameliorated after ADT cessation. Our cases indicate that MG in older male patients can be caused by an androgen effect.