Effects of fertility preservation in patients with breast cancer: A retrospective two-centers study.

Purpose: To assess the efficacy of fertility preservation (FP) and the impact of chemotherapy on the reproductive potential of Japanese patients with breast cancer.

Methods: Sixty-two patients with breast cancer visited the authors' centers from October, 2003 to June, 2015. They were divided into two groups according to the treatment: oocyte or embryo vitrification for FP before cancer treatment (group A) or infertility treatment after cancer treatment (group B). Group B was divided into two subgroups, B1 (no chemotherapy) and B2 (postchemotherapy), in order to analyze the effect of anticancer drugs on ovarian reserves and assisted reproductive technology outcomes. The number of retrieved oocytes, vitrified oocytes or embryos, and pregnancy rates were analyzed and compared: group A compared to group B1 compared to group B2.

Results: The patients in groups A and B1 underwent egg collection without any chemotherapy. The numbers of collected oocytes and vitrified embryos were significantly higher in groups A and B1 than in group B2. Nearly 50% of the in vitro fertilization patients who underwent an embryo transfer (ET) became pregnant, including two patients in group A who underwent a vitrified-warmed ET. Among the pregnant women, 70% did not have chemotherapy.

Conclusion: For patients with breast cancer, FP with unfertilized oocytes or embryos before chemotherapy seems to be promising for achieving higher pregnancy rates, with no risk of minimal residual disease.