Abstract P3-12-07: Dose delays, dose reductions, and relative dose intensity in early stage breast cancer patients receiving (neo)adjuvant chemotherapy in community oncology practices

Abstract

Abstract Background: Neutropenic complications, such as febrile neutropenia (FN), often necessitate delays or reductions in doses of myelosuppressive chemotherapy. The resulting reduced relative dose intensity (RDI) may lead to poorer disease-free survival and overall survival among patients with early stage (stage I-IIIA) breast cancer (ESBC) (Chirivella, 2009; Wildiers, 2011). Methods: Using the McKesson Specialty Health/US Oncology iKnowMed™ HER database, we retrospectively identified the first course of (neo)adjuvant chemotherapy received by female adult patients with ESBC who initiated treatment from 1/1/2007-3/31/2011. We then assigned patients to chemotherapy cohorts (standard regimens described in the NCCN breast cancer guidelines or in published phase 3 trials) based on chemotherapy agents received in cycle 1 and planned regimen information in the database. Only standard regimen cohorts containing ≥100 patients were included in this study. For each standard regimen cohort, we estimated the following statistics: the proportion of patients receiving colony-stimulating factor (CSF) prophylaxis in the first 5 days of cycle 1; mean RDI; and the incidences of reduced RDI (<85% over the course), dose delays (≥7 days in any cycle of the course), and dose reductions (≥15% in any cycle of the course) relative to the corresponding standard regimens. We conducted similar analyses of patient subgroups based on patient age and body surface area (BSA) at the time chemotherapy was initiated. Results: Study results by standard regimen cohortStandard regimen cohortNAge, mean (SD)CSF prophylaxis in cycle 1,%Mean RDI,% (SE)RDI <85%,%Dose delay ≥7 days,%Dose reduction ≥15%,%TC (4-cycle)3,41457.4 (11.0)50.789.6 (0.3)19.524.623.0TAC1,56750.6 (9.7)91.885.7 (0.5)27.136.234.8Dose-dense AC→Q2W paclitaxel1,27150.9 (10.3)89.193.5 (0.2)15.738.227.1TC (6-cycle)1,18057.3 (11.0)49.983.9 (0.6)34.440.741.7TCH1,13854.2 (11.5)55.679.4 (0.7)43.445.458.5AC→QW paclitaxel42153.9 (11.3)28.390.3 (0.5)21.957.046.6Dose-dense AC40451.9 (10.5)86.180.7 (1.1)42.344.838.4Dose-dense AC→QW paclitaxel38050.5 (10.2)92.191.1 (0.5)25.359.540.5AC39555.4 (11.1)30.482.9 (1.1)33.938.533.2AC→Q3W paclitaxel16655.7 (10.8)38.690.0 (0.7)28.350.644.0AC→docetaxel13456.0 (10.5)33.684.4 (0.9)44.854.576.1TC: docetaxel, cyclophosphamide; TAC: docetaxel, doxorubicin, cyclophosphamide; AC: doxorubicin, cyclophosphamide; TCH: docetaxel, carboplatin, trastuzumab; QW/Q2W/Q3W: every 1/2/3 week(s) Discussion: Chemotherapy dose delays, dose reductions, and reduced RDI were common in patients with ESBC treated in community oncology practices and their frequencies were higher in older patients and in patients with BSA >2 m2. Further research should evaluate the impact of these factors on patient outcomes. Study results by patient subgroupSubgroupNMean RDI,% (SE)RDI <85%,%Dose delay ≥7 days,%Dose reduction ≥15%,%Age <503,67788.6 (0.3)23.634.231.2Age 50-644,70487.6 (0.2)25.835.534.0Age 65-741,68784.7 (0.5)32.039.740.5Age ≥7540279.4 (1.2)42.046.549.2BSA ≤2 m28,62787.8 (0.2)25.335.833.5BSA >2 m21,84384.5 (0.4)33.237.639.8 Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P3-12-07.