Comparison of Treatment Completion Rate Between Conventional and Dose-dense Doxorubicin and Cyclophosphamide (AC) Followed by a Taxane in Patients With Breast Cancer: A Propensity Score-matched Analysis

To maximize the effect of perioperative chemotherapy in breast cancer, it is critical to keep the relative dose intensity (RDI) high. While bi-weekly doxorubicin and cyclophosphamide, dose-dense AC (ddAC), instead of tri-weekly conventional AC (cAC) followed by a taxane has been adopted as standard perioperative chemotherapy, postponement or discontinuation are sometimes experienced during ddAC or subsequent taxane phase. This study aimed at evaluating whether ddAC, compared to cAC, was associated with reduced RDI.We compared ddAC and cAC, both followed by a taxane, for perioperative breast cancer regarding the proportion of completion of planned treatment (%completion), defined as an RDI ≥85% for both AC and taxane phases.There was no remarkable difference between the groups in patient characteristics after propensity score matching (n=46 in ddAC, and n=86 in cAC). The %completion was similar between the groups (67.4% vs. 65.1%). Most other endpoints related to RDI were similar between groups. The incidence of pneumonia was higher in the ddAC group (13% vs. 3%) including one Pneumocystis jiroveci pneumonia.ddAC followed by a taxane can be considered with sufficient supportive measures and precautions for pneumonia.