[Freezing of ovarian tissue and outcome]

In females, aggressive chemotherapy and/or radiotherapy for the treatment of cancer can cause a significant reduction in the size of the follicle population within the ovaries, which may lead to a premature menopause. The cryopreservation of ovarian tissue is a promising new method for conserving the fecundity of these cancer patients prior to therapy. In animal studies the insertion of frozen-thawed ovarian autografts at the orthotopic site has led to a resumption of endocrine function and the restoration of fertility. Experimental studies on human ovarian tissue have indicated that viable and morphologically normal follicles are present after freeze-thawing and furthermore, that these follicles survive grafting beneath the kidney capsules of immunodeficient mice. Although ovarian tissue is now being stored from cancer patients, a procedure for using the banked material to restore fertility has not been established. Autografting has been successful in animal studies, but in cancer patients there is concern that the procedure may reintroduce malignant cells. Follicle isolation for subsequent growth to maturity in vitro is a preferable option, but this technology is in its infancy. This paper reviews past and present research in the field of ovarian tissue cryopreservation and investigates the possible strategies by which the frozen-banked tissue could be used to restore fertility. In addition, the practical aspects of clinical ovarian tissue cryopreservation will be discussed.