Abstract INTRODUCTION: Much progress has been made related to fertility preservation in women diagnosed with breast cancer. This includes heightened awareness of impaired fertility due to breast cancer treatment, increased referrals to fertility specialists and development of safe and expeditious means of egg harvesting. Nevertheless, there has been limited investigation of the ultimate issue in fertility preservation, namely the frequency with which women who have undergone egg harvesting actually pursue childbearing. We have retrospectively reviewed a single institution’s experience with egg and embryo utilization among patients who expressly desired childbearing and underwent egg harvesting after a diagnosis of breast cancer. These issues have also been analyzed relative to race and insurance coverage. METHODS: In an IRB approved study, breast cancer patients treated in our institution between 2010 and 2020 were identified and their post-diagnosis fertility and childbearing history was reviewed. Inclusion criteria were age at presentation ≤ 45 years and diagnosis of either invasive breast cancer or ductal carcinoma in situ. Race (self-reported on clinic intake form) and insurance coverage data were analyzed. In cases of incomplete medical record data, we interviewed patients by telephone. RESULTS: 316 breast cancer patients of reproductive age were identified (average age at diagnosis = 39 years, range: 23 - 45). Of these, 168 patients (53%) were offered fertility referral and 118 (38%) saw a fertility specialist. 91 patients (29%) pursued egg harvesting followed by cryopreservation of eggs in 49 cases and embryos in 41 with 1 case unknown. Over an average of 5 years of follow-up (range: 2 - 12 years), 28 women (31% of those who pursued egg harvesting) utilized the egg or embryo to pursue childbearing. 17 underwent embryo transfer to themselves and 11 used surrogate carriers. To date, this has resulted in 20 childbirths from 24 pregnancies. Four pregnancies are currently ongoing and 1 woman is awaiting embryo transfer. Four patients who had undergone egg harvesting conceived without fertility intervention. Of the 55 Medicaid patients of reproductive age diagnosed with breast cancer, only 8 (15%) met with a fertility specialist, 4 harvested eggs, and none pursued childbearing. HMO/PPO insured patients were significantly more likely than Medicaid patients to pursue egg harvesting and embryo utilization (X2 = 7.320, df = 2, p = 0.026). Of 260 HMO/PPO insured patients, 110 (42%) met with a fertility expert, 87 harvested eggs and 28 pursued embryo transfer. Due to the small sample size of patients who utilized embryos in each racial subgroup, analysis did not yield statistically significant differences across groups (p=0.067). Nevertheless, apparent racial disparities exist. Our data reveal that 5 of 17 (29%) Asian patients and 22 of 62 (36%) White patients utilized embryos as opposed to Black patients (1/4 or 25%), Hispanic patients (0/4 or 0%) and those who identified their race as “other” (1/4 or 25%). CONCLUSIONS: These data demonstrate a low overall rate of cryopreserved egg and embryo utilization among women treated for breast cancer whose earlier pursuit of egg harvesting was evidence of a desire for childbearing. Furthermore, racial and insurance data demonstrate disparities in the pursuit of fertility treatment and utilization of preserved eggs and embryos. Further research will utilize interviews to analyze individual women’s decision-making process relevant to such issues as hormone therapy utilization, concerns about breast cancer recurrence, progression of disease and restraints imposed by relationship status and finances. Given the disparity findings reported here, finances will likely emerge as a significant barrier to childbearing in future qualitative research. Citation Format: Christina Weltz, Daniella Nevid, Alison Pruzan, Elisa Port, Ronald Couri. Embryo utilization in young breast cancer patients who have undergone egg harvesting for fertility preservation [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P5-07-02.