Over the past 50 years, there has been a remarkable improvement in the cancer survival rates due to significant progress in the diagnosis and treatment. However, multi‐agent chemotherapy regimens and/or radiotherapy, and hematopoietic stem cell treatments are associated with significant long‐term sequels such as growth disorders, cardiovascular problems, neurocognitive abnormalities, secondary malignant tumors, and reproductive failure. Cytotoxic therapy has also been used in some non-malignant hematologic, immunologic, and genetic diseases, which are resistant to standard treatment modalities. Moreover, gonadal surgery for benign gynecological lesions including endometriomas may be associated with decreased ovarian reserve, even can result in a permanent ovarian failure especially if the disease is bilateral. It was projected that in 2020, there would be approximately 90.000 new cancer cases in adolescents and young adults, on the other hand overall cancer mortality declined by 1% annually, from 2008 to 2017 among all age and sex groups [1]. As a result of the increasing number of cancer survivors, a strong focus has been placed on the delayed effects of cancer treatments which can all affect future quality of life of the patients.
When selecting the most optimal option to preserve fertility one should analyze all possible confounding factors such as age of the patient, available time before cancer treatment, ovarian reserve, the type and duration of chemotherapy and/or radiotherapy, and couple status. There are currently various established and non-established techniques for fertility preservation performed worldwide. Embryo cryopreservation has long been practiced with high success rates which is quite similar to outcomes using fresh embryo transfer. Likewise, with the advent of modern freezing technologies including vitrification, the success rates with oocyte freezing have also remarkably increased. Before oocyte or embryo cryopreservation at least 2 weeks is required for ovarian stimulation before oocyte retrieval. For estrogen sensitive tumors including breast and endometrial cancers, safer ovarian stimulation protocols incorporating letrozole were defined with high success rates. Patients undergoing pelvic radiotherapy laparoscopic ovarian transposition can be performed, however the success rates vary between 16-90%. Ovarian tissue cryopreservation and transplantation is among one of the key components of available fertility preservation techniques with more than 200 reported livebirths worldwide. Transplantation of frozen thawed ovarian tissue is not only a viable option to achieve pregnancy, but it also enables resumption of reproductive functions by producing hormones that has a substantial impact on the quality of life of the patients suffering premature ovarian failure. One of the most important advantages of ovarian tissue freezing is that there is no need to delay cancer treatment since ovarian stimulation is not required. Although various methodologies have been tested in many animal and human studies for ovarian tissue freezing, until recently, this procedure has been classified as “experimental” as the precise methodology has not yet been established. However, with increased clinical success together with increasing number of healthy live births in recent years, ovarian tissue freezing is now considered as an "acceptable" method for fertility preservation. The feasibility of autologous hematopoietic stem cell transplantation to improve pregnancy rates in patients with poor ovarian reserve has also been investigated with reported success rates in limited number of recent studies.
