Additional Considerations for COS in Cancer Patients: Safety
Is COS safe in women with cancer?
There is little published data about the safety of a COS to bank embryos or oocytes prior to cancer treatments. Hypothetical risks include:
The risk of delaying cancer treatments to undergo a COS cycle
The risk that COS may itself increase the risk of cancer recurrence
Routine IVF risks may be heightened in a sicker cancer population
Background about the letrozole protocol
Oktay et al.1 performed a retrospective analysis of IVF cycles in women with hormone sensitive cancers, looking at outcomes such as oocyte yield, peak estradiol levels, and time to chemotherapy start (Table 1).
Azim et al.4 followed women who underwent this modified IVF protocol using letrozole prospectively, and reported on recurrence rates over the next 2-3 years. (Table 2)
Conclusions: No difference in recurrence rates of breast cancer in women who underwent a letrozole stimulation protocol, compared to women who did not.
1. Oktay K, Hourvitz A, Sahin G, et al. Letrozole reduces estrogen and gonadotropin exposure in women with breast cancer undergoing ovarian stimulation before chemotherapy. J Clin Endocrinol Metab 2006;91:3885-90.
2. Baynosa J, Westphal LM, Madrigrano A, Wapnir I. Timing of breast cancer treatments with oocyte retrieval and embryo cryopreservation. J Am Coll Surg 2009; 209: 603-7.
3. Lawrenz B, Jauckus J, Kupka M, Strowitzki T, con Wolff M. Efficacy and safety of ovarian stimulation before chemotherapy in 205 cases. Fertil Steril 2010; 94: 2871-3.
4. Azim AA, Costantini-Ferrando M, Oktay K. Safety of fertility preservation by ovarian stimulation with letrozole and gonadotropins in patients with breast cancer: a prospective controlled study. J Clin Oncol 2008;26:2630-5.
5. Oktay K, Turkcuoglu I, Rodriguez-Wallberg KA. GnRH agonist trigger for women with breast cancer undergoing fertility preservation by aromatase inhibitor/FSH stimulation. Reprod Biomed Online; 20:738-8.
6. Geisler J, Haynes B, Anker G, Dowsett M, Lonning PE. Influence of letrozole and anastrozole on total body aromatization and plasma estrogen levels in postmenopausal breast cancer patients evaluated in a randomized, cross-over study. J Clin Oncol 2002;20:751-7.
7. Azim A, Oktay K. Letrozole for ovulation induction and fertility preservation by embryo cryopreservation in young women with endometrial carcinoma. Fertil Steril 2007;88:657-64.
About the Author
Jennifer Mersereau, MD, MSCI, is an reproductive endocrinologist in the University of North Carolina's Department of Obstetrics and Gynecology. As the Director of the Fertility Preservation Program, she has extensive experience guiding patients and physicians through the oncofertility experience.
Page last updated March 14, 2012.