Reproductive technologies 1998: options available for the cancer patient

Recent advances in the field of reproduction have potentially opened opportunities for the preservation of the reproductive potential of young cancer patients with good long-term prognosis for survival. In the postpubertal male, cryopreservation of ejaculated sperm is both feasible and potentially successful. Semen parameters at the time of procurement are of minor significance; intracytoplasmic sperm injection (ICSI) can bypass sperm concentration and motility problems and can lead to successful fertilization. For the prepubertal male there are no clinically applicable options insofar as extraction and cryopreservation of postmeiotic sperm cells (mature spermatozoa or round spermatids) is not feasible. To date, efforts for culture of testicular tissue and in vitro maturation of male germ cells have not been successful. In both pre- and postpubertal females, cryopreservation of ovarian cortical tissue or enzymatically extracted follicles and the in vitro maturation of preantral follicles are of potential clinical use, but, to date, these approaches have been successful only in laboratory animals. An additional option available to the postpubertal female is the stimulation of ovaries with exogenous gonadotropins and retrieval of mature oocytes for cryopreservation. The recent application of ICSI in previously cryopreserved human mature oocytes has improved fertilization rates and has resulted in live births. Unfortunately, a shortcoming of this approach is the limited number of oocytes that can be harvested after stimulation of the ovaries. Further, all these approaches potentially harbor the risk of the cryopreservation of malignant cells with their subsequent reintroduction in the patient at a later date. This is a more realistic concern for patients suffering from hematologic or gonadal tumors. Finally, even though cryopreservation of embryos has been successfully used for many years, this option is not available to the pediatric and adolescent patient. It should not be forgotten that, even if the patients' own gametes are not available in the future, donor sperm and eggs provide the option for offspring and can give the opportunity to the females to carry a pregnancy as long as their uterus has not been affected by the cancer treatment. Given the rapid progress we are witnessing in the field of reproductive medicine, it is probable that in the very near future most of the options described and newer ones will be clinically available.