Ovarian Tissue Freezing in Cancer Patients - Transplantation and IVM

Abstract

Ovarian tissue cryopreservation (OTC) and subsequent grafting (OTG) is an innovative fertility preservation option, particularly for those patients who cannot delay treatment or are pre-pubertal. Unlike mature oocyte cryopreservation, OTC provides potential multiple opportunities for conception given the large supply of oocytes at immature stage. OTG is increasingly recognised as being successful in re-establishing fertility for women who have had gonadotoxic treatment, with over 200 live births documented worldwide from either spontaneous or assisted conception. However, establishing accurate clinical pregnancy rates and livebirth rates associated with IVF treatment after grafting is somewhat difficult as most studies publish pregnancy rates per patient rather than per transfer. Accurate information is important to assist patients with expectation management of numbers of cycles required to conceive and with outcomes, given this type of treatment is more labour-intensive than straightforward IVF. For patients with haematological cancers and with ovarian cancer there is a risk of tumour cell transmission and therefore strategies are required to allow use of the tissue and/or the gametes without conferring this risk. In-vitro-maturation offers the potential for healthy pregnancy and livebirth without the risk of grafting, and development of this technology will allow a robust and realistic fertility treatment strategy. However, how to successfully effect the initial phase of follicle development from primordial phase, termed the in-vitro-growth phase, is still eluding researchers. Mastery of this will allow substantial expansion of the follicle pool.