[Fertility and cancer].

Information about chemo and/or radiotherapy gonadotoxicity and about fertility preservation is essential. Sperm cryopreservation has to be systematically offered before gonadotoxic treatments. Efficiency of ovarian function preservation with GnRH agonists is still debated. A controlled ovarian stimulation is necessary before oocyte or embryo cryopreservation. It is only feasible if the treatment is not urgent and if the tumor is not hormone-sensitive. If the treatment is highly gonadotoxic, an ovarian tissue cryopreservation may be appropriate. It is the only fertility preservation technique feasible for prepubertal girls. It is now possible to preserve the fertility of prepubertal boys by cryopreservation of testicular tissue. It is essential to send patients and/or their parents to a specialized fertility preservation center.