Methods
Methods for fertility preservation
1. Women
Different strategies are available for fertility preservation in female and male cancer survivors.
Most useful techniques for women are gonadal shielding, oophoropexy, embryo cryobanking, for men semen cryobanking. Emerging strategies are hormonal ‘protection’, egg cryobanking, gonadal tissue/germ cell cryobanking with subsequent in vitro maturation or autotransplantation.
1.Farmacologic protection:
Limit ovarian toxicity by reducing ovarian function during chemotherapy.
In theory, ovarian toxicity from chemotherapy can be reduced by diminishing ovarian function during the period of treatment. This can be reversibly achieved by the administration of gonadotropin-releasing hormone (GnRH) agonists or oral contraceptives. The evidence of benefit from such an approach in humans is limited and use of these agents for this purpose is controversial.
2. Surgical transposition:
Oophoropexy. Attempts to reduce the toxicity of radiation exposure by moving the ovaries to the lateral pelvic walls (oophoropexy) have been variably successful, presumably because of scatter radiation and surgically induced changes in ovarian blood supply or innervation, or proximity to the fallopian tubes.
3.Cryopreservation
The effect of very low temperature on survival of gonadal cells and tissues is an area of extensive research in reproductive biology. The ability to preserve oocytes and ovarian tissues in a healthy state for a variable duration gives the patient who will undergo cancer treatment another option to preserve her fertility.
2. Men
The best option for preserving capacity for fertility is cryostorage of sperm prior to initiating cancer therapy (especially considering that only 20-50% of these subjects resume spermatogenesis after completing treatment). Suppression of testicular function by administration of a GnRH agonist has not been successful.
So, in postpubertal males, sperm banking should be offered as soon as the diagnosis of any malignant disease is established, irrespective of the expected cryosurvival rate. In such cases, conception can be achieved with frozen-thawed spermatozoa following either intrauterine insemination (IUI) of intracytoplasmic sperm injection (ICSI).
The situation is much less clear in prepubertal males where cryopreservation of testicular tissue or isolated spermatogonia can be offered but there is still no proof that autotransplantation can lead to recovery of spermatogenesis. Optimized methods for in vitro maturation of the immature male gamete are also not available as yet.
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