**Fertility Preservation for Pre-Pubertal Girls and Young Female Cancer Patients**

R. Gerritse1,2, L. Bastings1,3, C.C.M. Beerendonk1,

J.R. Westphal1, D.D.M. Braat1 and R. Peek1,4 *1Radboud University Nijmegen Medical Centre, Department Obstetrics and Gynaecology Nijmegen, 2Koningin Beatrix Ziekenhuis Winterswijk, The Netherlands, 3Jeroen Bosch Hospital 's Hertogenbosch, The Netherlands* 

#### **1. Introduction**

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New protocols in the early diagnosis and treatment of cancer have led to major improvements in the long-term survival of patients. However, aggressive chemotherapy or radiotherapy of the pelvic region, often lead to infertility, due to the damage of the follicles and/or oocytes that are present in the ovaries. In women the probability of sterilization due to cancer therapy varies with age, the type of treatment, and the follicular reserve in the ovary. Safeguarding their reproductive potential is a very important issue for women that have not yet started or completed their family, and even more so in pre-pubertal girls. Several options, some of which are still in the experimental phase, can now be offered to these women to (partially) preserve their fertility.

In this review, we will, after briefly describing the anatomy and physiology of an ovary, discuss the detrimental effects of chemotherapy and radiation on ovarian function. Subsequently, the various options that are currently available or are still in an experimental phase, for preserving fertility in women and pre-pubertal girls, will be discussed. These options (with the exception of option (i)), deal with cryopreserving either oocytes, embryos or ovarian tissue until the patient has been cured.


Fertility Preservation for Pre-Pubertal Girls and Young Female Cancer Patients 197

In this paper we confine ourselves to fertility preservation for female patients. We discuss the causes of anti-cancer therapy-related infertility, and review the current options for fertility preservation. We illustrate this matter with two case reports from our own clinical practice. In addition we discuss some as yet experimental procedures, that may in the future

The human ovary is spherical structure with a mean volume of 7 cm3 (range 2-15 cm3; Munn et al., 1986). The inner ovarian mass, the medulla, consists mainly of stromal cells and contains the larger blood vessels. The outer layer of the ovary consists of the cortical tissue, spanning 2-3 mm. This tissue is rich in extra-cellular matrix proteins and poor in capillaries , and contains the vast majority of the follicles containing oocytes that comprise the ovarian reserve. The most important role of the follicle is to protect the oocyte, and support its development. Follicles are comprised of layer(s) of theca cells and granulosa cells. Different stages of follicles can be distinguished, ranging from primordial follicles to primary follicles,

In contrast to males in whom spermatogenesis is a continuous process resulting in the uninterrupted generation of fresh spermatozoa, in women a fixed number of oocytes is formed during embryogenesis from 1000-2000 germ cells. These germ cells are present in the human embryo at 30 days after conception. After 9-10 weeks, these cells transform to oogonia (Baker, 1972), that degenerate for the greater part between 10 and 20 weeks of gestation. After 5 months of gestation, the first meiotic division is initiated in the remaining oogonia, resulting in the differentiation to primary oocytes. At this stage the meiotic division process is arrested, and the oocytes enter a stage of dormancy (Wandji, 1996). At birth only 300.000 to 400.000 oocytes remain in the ovaries. From birth, the number of oocytes gradually decreases, and at the beginning of puberty around 200.000 oocytes remain. Under the influence of pituitary gonadotropic hormones (Gougeon, 1996; Oktay, 1997), each month a cohort of primary oocytes is recruited, and resumes development. Usually only one primary oocyt completes the first meiotic division. This secondary oocyt again enters a stage of dormancy, and is ovulated. The second dormant stage is only lifted after fertilization by a sperm cell. Around the age of 50 years, the total oocyte reserve is almost depleted and the woman enters menopause. In addition to age, several factors may affect the follicular reserve, leading to an early exhaustion and to premature ovarian insufficiency (POI). These factors include fertility-threatening

Cytotoxic therapy may affect all components of the follicle, including granulosa cells, theca cells, and of course the oocyt itself (Sobrinho et al., 1971; Blumenfeld et al., 1999). In addition, interactions between these cell types that are required for oocyt development may be disturbed, resulting in the demise of the oocyt. Damage may become manifest by reduced ovarian weight, stromal fibrosis and in a reduction in the number of oocytes and ovarian

The effect of chemotherapy on fertility is dependent on the type of the cytotoxic agent, the dose, and the duration of the therapy. Alkylating agents such as cyclophosphamide, L-

be offered to patients requiring fertility preservation.

**2. Ovaries, oocytes and female reproduction** 

and via secondary finally to tertiary (antral) follicles.

therapies that are discussed in more detail in the next section.

**3.1 Chemotherapy** 

**3. Effects of radio- and chemotherapy on female fertility** 

follicles (Warne et al., 1973; Meirow et al., 1999; Oktem & Oktay, 2007).

treatment is not an option for pre-pubertal girls, or for post-pubertal girls who are not yet involved in a stable relationship.


Finally, we will go into the safety of the procedure. Inevitably the autotransplantation of cortical strips or intact ovaries carries the risk of reintroducing malignant cells from the graft into the recipient.

The increase in knowledge of the biology and treatment of cancer has been accompanied by an increase in the efficacy of cancer therapies. Long term survival rates for many cancer types have therefore increased accordingly (Gatta et al., 2009). Consequently, the quality of life of cancer survivors is becoming an important issue.

The possibility to have genetically concordant progeny is for many people an event that is essential for an unrestricted quality of life as an adult (Schover, 2009). The loss of fertility that may result from cancer therapy, is therefore an additional complication on top of an already difficult period spent on conquering a devastating disease.

With this in mind, it is of the utmost importance to explore the possibilities for fertility preservation in patients that are to be treated with a gonado-toxic therapy. For post-pubertal boys and men, this can be achieved relatively easy via the cryopreservation of their semen prior to start of the therapy. For pre-pubertal boys this is not an option, as semen production is initiated during puberty. Also for this group of patients options for fertility preservation are being developed.

In this paper we confine ourselves to fertility preservation for female patients. We discuss the causes of anti-cancer therapy-related infertility, and review the current options for fertility preservation. We illustrate this matter with two case reports from our own clinical practice. In addition we discuss some as yet experimental procedures, that may in the future be offered to patients requiring fertility preservation.
