Introduction: Administering pegfilgrastim on the same day as chemotherapy can improve patient satisfaction through convenience and may increase the utilization of cost-effective biosimilars compared to next-day administration, but the effect on clinical outcomes with commonly used breast cancer regimens is unclear.
Methods: This multi-site, retrospective cohort study included breast cancer patients age 18 years or older who received dose-dense doxorubicin and cyclophosphamide (ddAC) and pegfilgrastim between 1 June 2016 and 31 May 2020. Pegfilgrastim was given on the same day as chemotherapy at one site and the day after chemotherapy at the other two sites.