I-37: Controlled Ovarian Stimulation in Cancer Patients

Recent advances in the technology of vitrification of human oocytes and embryos have increased the opportunities for fertility preservation in cancer patients. Ovarian stimulation in this group of patients is associated with some unique challenges. A controversy in this field rotated around the hypothesis that the transient elevations of estrogen during an IVF cycle may stimulate tumor growth; therefore, increasing the risk of treatment failure or cancer recurrence. However, this is a hypothetical jeopardy and no studies have reported that a single IVF cycle exacerbated the risk of poor oncologic outcomes. Some centers attempt to alleviate the peak estrogen levels during stimulation, using a modified IVF protocol developed by Oktay et al. This modified protocol uses anti-cancer hormonal treatment during an “Antagonist Cycle”.Ideal protocol of superovulation for this group of patients includes a compromise between obtaining a relatively large number of oocytes for vitrification, to maximize chances of later pregnancy, and the absolute need for avoidance of ovarian hyperstimulation syndrome (OHSS) in a patient who will shortly begin chemotherapy. These studies, in general, demonstrate that COS cycles for women with cancer are similar to those of women without cancer. A GnRH antagonist protocol with moderately high dose of FSH, possibly determined by pre-treatment AMH, may be an appropriate option. Most studies report using an antagonist protocol, as this allows the quickest start of stimulation. However, some patients used a protocol with GnRH-agonist or some centers used tamoxifen or letrozole for women with hormone-sensitive cancers. Some centers tended to be more conservative (lower starting dose) for cancer patients to minimize the risk of OHSS, other centers used standard starting doses, or even slightly higher doses, given that this was likely the couple’s attempt at COS, and they wanted to minimize the risk of poor response. For women with cancer, the overall gonadotropin usage was found to be similar in majority of previous studies. For patients planning to commence chemotherapy, timing of fertility preservation techniques can significantly influence the decision making process. However, if there is no time, or for women with haematologic disorders, there may significant pressure to avoid delays in chemotherapy; in this situation it is possible to commence fertility treatment in either the pre-ovulatory or luteal phase by using a GnRH antagonist for 2-5 days to produce a profound decrease in gonadotropins and then commence FSH stimulation. There is no data to suggest the ideal method of fertilization, some centers use standard ICSI criteria, while others use ICSI for all embryo banking cases to avoid the risk of fertilization failure.