Added Benefit of Immature Oocyte Maturation for Fertility Preservation in Women with Malignancy.

To assess the added value of maturing immature oocytes collected during fertility preservation treatments in women with malignancy. A retrospective case-control study analyzing the results of 327 cancer patients undergoing fertility preservation treatments. Oocyte maturation rates and cycle parameters were compared between 3 types of fertility preservation treatments: (1) stimulated IVF cycle (n = 143), (2) non-stimulated IVM cycle (n = 158), (3) follicle aspiration and oocyte collection from ovarian tissue prepared for ovarian tissue cryopreservation followed by in vitro maturation of the immature oocytes (n = 48). The primary outcome measure was the maturation rate and the number of mature oocytes. The secondary outcomes were oocyte fertilization and embryo development rates. The mean maturation rate in IVF cycles was 38% and in the non-stimulated IVM cycles was 55%. In women who chose to cryopreserve their embryos, similar fertilization and embryo cleavage rates were found in oocytes that matured after stimulated IVF cycles compared to non-stimulated IVM cycles. Gonadotropin-releasing hormone agonist triggering, treatment with aromatase inhibitor, or oral contraceptives use before the cycle did not affect the maturation rate. Ovarian stimulation yields the highest number of oocytes or embryos for cryopreservation. Although the maturation rate of immature oocytes collected in stimulated IVF cycles is low, it is still a viable source of oocytes that can be used to improve the efficacy of fertility preservation treatments by increasing the number of mature oocytes available for freezing or fertilization.