Cryoconservation du tissu ovarien en cancérologie pédiatrique

Recent advances in cancer therapy have improved the survival rate of children and adolescents facing cancer. Gonadotoxic therapies during childhood may impair future fertility. Fertility preservation technologies should be proposed before starting gonadotoxic treatments. Ovarian tissue cryopreservation is one option to preserve fertility in prepubertal girls and should be considered if the risk of premature ovarian failure is high. This approach does not delay oncologic treatment and offers great hope because it has the potential to preserve primordial follicles, which could subsequently be used, either in vivo (autograft of ovarian tissue) or in vitro (ovarian follicular growth) to obtain mature oocytes. To date, at least 26 live births are the result of transplantation of frozen/thawed ovarian cortex. The first case of fertility restoration by autograft of ovarian tissue in a girl that froze tissue before the onset of menarche has been recently published. This option is not viable for all patients because of the risk of reintroduction of the disease as the tissue is removed before gonadotoxic treatments. The full potential of this tissue to restore fertility could be achieved by the development of in vitro systems that support oocyte development from the immature stages to maturation. To date, in human species, no mature oocyte has been obtained after in vitro follicular maturation. Concerning the capacity of prepubertal ovarian cortex to develop and function correctly after reimplantation, it has been shown twice that transplanted prepubertal ovarian tissue can induce puberty confirming the functional capacity of frozen-thawed prepubertal ovarian tissue.