Assisted reproduction and breast cancer.

Breast cancer is the most frequent cancer in reproductive age women. Although well known causal link between estrogen and breast cancer, the impact of ovulation induction on the risk of breast cancer still remains to be clarified. One of the recently recognized long term adverse effects of adjuvant cytotoxic chemotherapy given for breast cancer is premature ovarian failure and infertility, both of which significantly compromise the quality of life of a cancer survivor. Thanks to significant developments in assisted reproductive technologies these patients may benefit from a wide range of fertility preservation options. The most established technique is embryo cryopreservation; oocyte cryopreservation can be considered in single women; both of which require at least 2 weeks of ovarian stimulation beginning with the onset of the patient's menstrual cycle. Novel ovarian stimulation protocols using tamoxifen and letrozole can be used to increase the margin of safety in estrogen sensitive breast tumors. When there is no time available for ovulation induction, ovarian tissue can be cryopreserved for future transplantation without delay in cancer therapy. The benefit of ovarian protection by gonadotropin-releasing hormone analogues is unproven and unlikely, and thus this treatment should not be recommended as the sole method of fertility preservation.