Much of the focus in the new field of oncofertility has been on preserving cancer patients' fertility prior to treatment that is likely to diminish their fertility or render them sterile. Less attention, however, has been paid to the logistics of using frozen eggs, embryos, or ovarian tissue following cancer treatment. It is usually assumed that, following some manipulation, the frozen eggs, embryos, or ovarian tissue will be transferred back into the women's bodies via assisted reproductive technology (ART) so that they can become pregnant. Some women, however, cannot utilize this technology because their cancer treatment has left them unable to gestate. If these women desire biological children and have banked eggs, embryos, or ovarian tissue, then the only option available to them is surrogacy.