Restoration of fertility after treatment for cancer.

The late effects of chemotherapy and radiation treatment on fertility are an important issue for long-term survivors of cancer who may not have started or completed a family at the time of diagnosis. Attempts at protecting reproductive function using hormonal manipulation have proved largely unsuccessful and other strategies have to be considered. For men, semen cryopreservation allows subsequent artificial insemination of a female partner or ivf but cryopreserved semen is a finite resource, does not allow natural conception and is not an option for prepubertal boys. In an effort to overcome this, research is in progress to investigate whether testicular cells harvested and cryopreserved before the start of chemotherapy can be reintroduced to the testis after treatment and resume normal spermatogenesis. This has been achieved in a mouse model and the results of experimental protocols in men are awaited with interest. For women, harvested mature oocytes are only poorly tolerant of the freezing process although immediate in vitro fertilization and cryopreservation of embryos can be successful. An experimental technique of great interest is the harvesting and cryopreservation of ovarian cortex before the start of sterilizing treatment. In ewes, the reimplantation of autologous ovarian cortical tissue into surgically castrated animals has resulted in resumption of oestrus, conceptions after normal matings and the birth of live offspring. Recently, ovarian function has been re-established using a similar technique in a patient following treatment for Hodgkin's lymphoma, but so far pregnancy has not been reported.