Restoration of spermatogenesis by hormone treatment after cytotoxic therapy

Cytotoxic therapy is effective in treating various cancers, but many of the agents used can cause sterility in men, regardless of the age at which they were treated. Originally, it was thought that infertility in individuals who had undergone cytotoxic therapy resulted from the destruction of stem spermatogonia. However, studies using rats suggest that some stem spermatogonia can survive cytotoxic therapy and that infertility is caused by the inability of these spermatogonia to differentiate. The author believes that the failure of these cells to differentiate may be related to the high levels of intratesticular testosterone encountered in these situations. In rats that have previously received cytotoxic therapy, the administration of a gonadotrophin-releasing hormone (GnRH) agonist restores the ability of spermatogonia to differentiate, and as a result normal spermatogenesis returns. This finding suggests that GnRH agonists show promise as a treatment for male sterility induced by cytotoxic therapy, although further studies are required.