Fertility preservation is the effort to help cancer patients retain their fertility, or ability to procreate. Research into how cancer affects reproductive health and preservation options are growing, sparked in part by the increase in the survival rate of cancer patients.
Cancer treatment 
Chemotherapy and radiation treatments for cancer and other serious illnesses can affect reproductive health. The regimens that threaten ovarian and testicular function are mainly radiation therapy to the pelvic area and some types of chemotherapy. Chemotherapies with high risk include procarbazine and alkylating drugs such as cyclophosphamide, ifosfamide, busulfan, melphalan, chlorambucil and chlormethine. Drugs with medium risk include doxorubicin and platinum analogs such as cisplatin and carboplatin. On the other hand, therapies with low risk of gonadotoxicity include plant derivatives such as vincristine and vinblastine, antibiotics such as bleomycinand dactinomycin and antimetabolites such as methotrexate, mercaptopurine and 5-fluoruracil.
These regimens attack rapidly dividing cells in the body, including healthy cells like sperm and those belonging to the ovarian follicle (egg). Depending on the dose and duration of administration, these therapies can have varying effects on reproductive health. Surgery involving reproductive tissue affects reproductive function and fertility.
For many cancer patients, the decrease or loss of reproductive function is temporary; many men and women, however, do not regain fertility after cancer treatment. Patients undergoing serious radiation, chemotherapy, or surgery sometimes experience symptoms resembling menopause (in women) or andropause (in men), which indicate reproductive damage. In women, decreased estrogen levels as a result of ovarian deficiency lead to weakened bone, changes in temperature control, altered mood, and decreased sexual desire. Men with testicular insufficiency also experience similar symptoms.
A study indicated that fewer oocytes are recovered from cancer patients wanting to perform embryo preservation when compared with an age-matched control group, but the mean number of zygotes generated appears to be similar. The same study found that, of 65 patients referred to the program, 28% declined to undergo embryo, oocyte, or tissue cryopreservation. 9% were found not to be eligible for medical reasons. Of the remaining 41 patients, 85% chose to cryopreserve embryos, 10% chose to cryopreserve oocytes, and 5% chose to undergo ovarian tissue freezing. No serious clinical sequelae resulted from participation.
The main methods of fertility preservation are ovarian protection by GnRH agonists, cryopreservation of ovarian tissue, eggs or sperm, or of embryos after in vitro fertilization. The patient may also choose to use egg or sperm from a donor by third party reproduction rather than having biological children.
Semen cryopreservation 
Men hoping to preserve their fertility before undergoing treatment for cancer or another fertility-threatening disease can cryopreserve, or freeze, their sperm, which can be obtained through masturbation in post-pubescent boys and men. This is the most established fertility preservation method for males. For pre-pubescent boys, sperm can be obtained through testicular aspiration or electrostimulation and then stored for future use. Researchers are also looking at methods for cryopreserving testicular tissue samples so that they can be re-implanted into the body after treatment.
Cryopreservation of ovarian tissue or oocytes 
Some female patients choose to have mature eggs extracted and fertilized outside of the body with sperm from a partner or donor. The resulting embryo is then frozen until the woman is in remission from disease. When the woman is ready to initiate pregnancy, the embryo is thawed and implanted into the uterus for maturation and birth. While this option is the most common fertility preservation method in women, it is not available to pre-pubescent girls, who do not have mature eggs that can be fertilized. Women who do not have a partner will need to use donor sperm. Additionally, because this procedure requires a two-week period of hormonal stimulation to encourage egg maturation, it is not optimal for female patients who are diagnosed with hormone-sensitive cancers (such as breast cancer, ovarian cancer, etc.) or those who cannot delay cancer treatment. Alternative methods of hormonal stimulation using letrozole or tamoxifen may be used for women with hormone-sensitive cancers.
Strips of cortical ovarian tissue can also be cryopreserved, but it must be re-implanted into the body to allow the encapsulated immature follicles to complete their maturation. Furthermore, ovarian tissue is fragile under hard freezing conditions and putting it back into the body carries the risk of re-introducing cancerous cells.
Immature eggs are more tolerant of cryopreservation conditions but still cannot be effectively matured outside of the body. Thus far, this has generated two live births in mice, and scientists are working to translate these methods to humans.
GnRH agonists 
Third-party reproduction 
Many patients diagnosed with a malignancy or another disease requiring treatment that may impair their fertility consider alternatives to bearing biological children, such as assisted reproductive technology (ART) using in vitro fertilization (IVF) with donor eggs or donor sperm. The resulting embryo can be implanted into the woman's uterus after her endometrium (the lining of the uterus) is stimulated with hormones to prepare for the development of the embryo.
- Brydøy M, Fosså SD, Dahl O, Bjøro T (2007). "Gonadal dysfunction and fertility problems in cancer survivors". Acta Oncol 46 (4): 480–9. doi:10.1080/02841860601166958. PMID 17497315.
- Klock, S.; Zhang, J.; Kazer, R. (2010). "Fertility preservation for female cancer patients: early clinical experience". Fertility and Sterility 94 (1): 149–155. doi:10.1016/j.fertnstert.2009.03.028. PMID 19406395.
- Cruz, M.; Prestes, J.; Gimenes, D.; Fanelli, M. (2010). "Fertility preservation in women with breast cancer undergoing adjuvant chemotherapy: a systematic review". Fertility and Sterility 94 (1): 138–143. doi:10.1016/j.fertnstert.2009.02.055. PMID 19339000.
Further reading 
- Oktay, K.; Karlikaya, G (2000). "Ovarian function after transplantation of frozen, banked autologous ovarian tissue.". New England Journal of Medicine 342 (25): 1919. doi:10.1056/NEJM200006223422516. PMID 10877641.
- Bahadur, G. (2000). "Fertility Issues for Cancer Patients". Molecular and Cellular Endocrinology 169 (1-2): 117–122. doi:10.1016/S0303-7207(00)00364-6. PMID 11155943.
- Early Menopause (Premature Ovarian Failure). American Society for Reproductive Medicine. 1996
- Howell, S.J.; S.M. Shalet (2005). "Spermatogenesis After Cancer Treatment: Damage and Recovery". Journal of Natural Cancer Institute Monographs 34: 12–17.
- Lawrence, N.M. (2004). "What is the best approach to ovarian failure?". Contemporary OB/GYN: 46–55.
- Lee, S. J.; Leslie R. Schover, Ann H. Partridge, Pasquale Patrizio, W. Hamish Wallace, Karen Hagerty, Lindsay N. Beck, Lawrence V. Brennan, Kutluk Oktay (2006). "American Society of Clinical Oncology Recommendations on Fertility Preservation in Cancer Patients". Journal of Clinical Oncology (18 ed.) 24: 1–11.
- Mayo Foundation for Medical Education and Research (2007). "Cancer treatment for men: Possible sexual side effects.". MayoClinic.com
- Magelssen, H.; M. Brydoy, S.D. Fossa (2006). "The effects of cancer and cancer treatments on male reproductive function". Nature Clinical Practice Urology (6 ed.) 3 (6): 312–322. doi:10.1038/ncpuro0508. PMID 16763643.
- Petak, S. M.; Nankin, HR; Spark, RF; Swerdloff, RS; Rodriguez-Rigau, LJ; American Association of Clinical Endocrinologists (2002). "American Association of Clinical Endocrinologist Medical Guidelines for Clinical Practice for the Evaluation and treatment of Hypogonadism in Adult Male Patients - 2002 Update". Endocr Pract (6 ed.) 8 (6): 440–456. PMID 15260010.
- Azim, A.A.; Costantini-Ferrando M, Lostritto K, Oktay K. (2007). "Relative potencies of anastrozole and letrozole to suppress estradiol in breast cancer patients undergoing ovarian stimulation before in vitro fertilization.". J Clin Endocrinol Metab. 92 (6): 2197–200. doi:10.1210/jc.2007-0247. PMID 17356042.
- Oktay, K.; Hourvitz A, Sahin G, Oktem O, Safro B, Cil A, Bang H. (2006). "Letrozole reduces estrogen and gonadotropin exposure in women with breast cancer undergoing ovarian stimulation before chemotherapy.". J Clin Endocrinol Metab. 91 (10): 3885–90. doi:10.1210/jc.2006-0962. PMID 16882752.
- Woodruff, Teresa Kaye; Karrie Ann Snyder (2007). Oncofertility: Fertility Preservation for Cancer Survivors (Cancer Treatment and Research). Chicago: Springer. ISBN 978-0-387-72292-4.
- Oktay, K.; Buyuk, E; Veeck, L; Zaninovic, N; Xu, K; Takeuchi, T; Opsahl, M; Rosenwaks, Z (2004). "Embryo development after heterotopic transplantation of cryopreserved ovarian tissue". The Lancet 363 (9412): 837–40. doi:10.1016/S0140-6736(04)15728-0. PMID 15031026.