Fertility preservation for boys with cancer.

Childhood cancer is a curable disease due to the development of chemo- and radiation therapies, but long-term survivors suffer late side-effects including infertility. Cytotoxic agents and radiation impair spermatogenesis and cause oligospermia or azoospermia as well as genetic damage in sperm. To date, the only established option to preserve fertility is cryopreservation of sperm before treatment and artificial reproduction techniques, if men with cancer can ejaculate, but only a quarter of men have banked sperm. Lack of information is the most common reason for failing to bank sperm. However, prepubertal patients who have only spermatogonia and spermatocytes in their testes do not benefit from cryopreservation of their sperm and assisted reproductive techniques. Thus, the only available option is to harvest testicular tissues before treatment for cryopreservation, from which immature germ cells can somehow be maturated. Autotransplantation of germ cells into the testis holds promise for fertility restoration, but contamination by malignant cells may induce relapse. Fluorescence-activated cell sorting (FACS) with two surface markers could exclude contaminated leukemic cells from murine germ cells, and transplantation of sorted germ cells successfully restored fertility without transmission of leukemia. Human germ cells could be also isolated from human leukemia and lymphoma cell lines by FACS using surface markers. Before autotransplantation can be applied clinically, some issues, including the risk of contamination by malignant cells and in vitro propagation of spermatogonial stem cells, should be resolved.