Safety of ovarian stimulation

In women with cancer does the use of ovarian stimulation for oocyte retrieval increase the risk of cancer recurrence?

Women diagnosed with cancer are often concerned about the safety of ovarian stimulation for oocyte retrieval and fertility preservation. The role of hormones in breast cancer has ensured the majority of studies on the impact of ovarian stimulation on cancer recurrence have examined outcomes in breast cancer patients. High quality evidence from randomised controlled trials of ovarian stimulation is unlikely in this setting due to ethical considerations.

Two prospective cohort studies have examined the question in breast cancer patients. The first study examined 215 women recently diagnosed with breast cancer. Controlled ovarian stimulation was performed with letrozole and gonadotropins in 79 women, with 136 women serving as controls. The study found that ovarian stimulation was unlikely to result in recurrence of breast cancer, although follow-up longer than two years is necessary to confirm these results.^[1] A similar study of controlled ovarian stimulation with letrozole in breast cancer patients found that after five years there was no difference between the relapse-free survival of women who were treated for fertility preservation compared to those who were not.^[2]

Four retrospective cohort studies of ovarian stimulation in breast cancer patients also came to the same conclusion; no change in recurrence rate for breast cancer patients who underwent ovarian stimulation for fertility preservation.^[3][4][5][6] The strength of this conclusion is weakened by the limitations of the studies including low patient numbers, retrospective study design and the use of surrogate markers. The heterogeneous nature of breast cancers and breast cancer treatment also makes predicting individual risk of recurrence difficult.^[7]