As many as 10% of adults diagnosed with cancer in the UK are in the reproductive age between 25 and 49 years. There are twice as many cancer cases in women of this age group in comparison with men (Cancer Research UK). Advances in anti-cancer therapy have resulted in improved survival promoting a greater focus on quality of life issues, of which future fertility plays an integral role. The age of childbearing has become progressively older (Office of National Statistics) and as such many of these women may not have even started or completed their family.
Several options for fertility preservation (FP) could be considered in female patients depending on their age, ovarian reserve, type of cancer, timeframe (urgency of need to start treatment) and their wishes.
The following FP options are available:
Ovarian tissues preservation and transplantation
Medical protection with gonadotropin-releasing hormone (GnRH) agonists
This chapter will cover current available options, explain principles of controlled ovarian stimulation (COS) and discuss risks and benefits of different methods. In addition, data on national UK experience will be presented.
The option of egg/embryo freezing requires COS. The main principles of COS are based on the following:
Administration of FSH above the natural FSH threshold for follicular recruitment. The follicle-stimulating hormone (FSH) threshold is the level that initiates the final stage of follicular development from the early antral to pre-ovulatory stage of the dominant follicle.
Extending the ‘FSH window’. The duration of the rise in FSH above a critical threshold governs the number of dominant follicles selected from the recruited cohort for preferential growth.1 This is the ‘FSH Window Concept’.2 The duration of FSH above the threshold is short in the natural cycle, as newly growing follicles trigger the drop in FSH level through negative feedback. This drop results in only one follicle maintaining the ‘energy’ of growth which eventually results in a single dominant follicle capable of ovulation. Widening the ‘FSH window’ allows multiple follicles to be selected at the same time. Artificially administered FSH in constant amounts, which consistently exceed the natural threshold level, allows sustained multiple follicular development during COS (Figure 2.1).
Controlling the time of ovulation. Adequately grown follicles are capable of triggering release of luteinizing hormone (LH) which eventually governs the completion of the oocyte maturation process and ovulation. To improve the efficiency of COS, the natural release of LH is blocked and an artificial ovulation trigger is given to time the egg collection 36 h later. By this time the follicles will have gained all the necessary competencies of mature eggs, but their release will not yet take place. Hence all mature eggs derived from ovarian stimulation can be collected simultaneously and preserved for future use.
FSH levels and follicular recruitment in ...