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 cohort

Standard regimen cohort Age, mean (SD) CSF prophylaxis in cycle 1,% Mean RDI,% (SE) RDI <85%,% Dose delay ≥7 days,% Dose reduction ≥15%,% 
TC (4-cycle) 3,414 57.4 (11.0) 50.7 89.6 (0.3) 19.5 24.6 23.0 
TAC 1,567 50.6 (9.7) 91.8 85.7 (0.5) 27.1 36.2 34.8 
Dose-dense AC→Q2W paclitaxel 1,271 50.9 (10.3) 89.1 93.5 (0.2) 15.7 38.2 27.1 
TC (6-cycle) 1,180 57.3 (11.0) 49.9 83.9 (0.6) 34.4 40.7 41.7 
TCH 1,138 54.2 (11.5) 55.6 79.4 (0.7) 43.4 45.4 58.5 
AC→QW paclitaxel 421 53.9 (11.3) 28.3 90.3 (0.5) 21.9 57.0 46.6 
Dose-dense AC 404 51.9 (10.5) 86.1 80.7 (1.1) 42.3 44.8 38.4 
Dose-dense AC→QW paclitaxel 380 50.5 (10.2) 92.1 91.1 (0.5) 25.3 59.5 40.5 
AC 395 55.4 (11.1) 30.4 82.9 (1.1) 33.9 38.5 33.2 
AC→Q3W paclitaxel 166 55.7 (10.8) 38.6 90.0 (0.7) 28.3 50.6 44.0 
AC→docetaxel 134 56.0 (10.5) 33.6 84.4 (0.9) 44.8 54.5 76.1 
Standard regimen cohort Age, mean (SD) CSF prophylaxis in cycle 1,% Mean RDI,% (SE) RDI <85%,% Dose delay ≥7 days,% Dose reduction ≥15%,% 
TC (4-cycle) 3,414 57.4 (11.0) 50.7 89.6 (0.3) 19.5 24.6 23.0 
TAC 1,567 50.6 (9.7) 91.8 85.7 (0.5) 27.1 36.2 34.8 
Dose-dense AC→Q2W paclitaxel 1,271 50.9 (10.3) 89.1 93.5 (0.2) 15.7 38.2 27.1 
TC (6-cycle) 1,180 57.3 (11.0) 49.9 83.9 (0.6) 34.4 40.7 41.7 
TCH 1,138 54.2 (11.5) 55.6 79.4 (0.7) 43.4 45.4 58.5 
AC→QW paclitaxel 421 53.9 (11.3) 28.3 90.3 (0.5) 21.9 57.0 46.6 
Dose-dense AC 404 51.9 (10.5) 86.1 80.7 (1.1) 42.3 44.8 38.4 
Dose-dense AC→QW paclitaxel 380 50.5 (10.2) 92.1 91.1 (0.5) 25.3 59.5 40.5 
AC 395 55.4 (11.1) 30.4 82.9 (1.1) 33.9 38.5 33.2 
AC→Q3W paclitaxel 166 55.7 (10.8) 38.6 90.0 (0.7) 28.3 50.6 44.0 
AC→docetaxel 134 56.0 (10.5) 33.6 84.4 (0.9) 44.8 54.5 76.1 

TC: 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 subgroup

Subgroup Mean RDI,% (SE) RDI <85%,% Dose delay ≥7 days,% Dose reduction ≥15%,% 
Age <50 3,677 88.6 (0.3) 23.6 34.2 31.2 
Age 50-64 4,704 87.6 (0.2) 25.8 35.5 34.0 
Age 65-74 1,687 84.7 (0.5) 32.0 39.7 40.5 
Age ≥75 402 79.4 (1.2) 42.0 46.5 49.2 
BSA ≤2 m2 8,627 87.8 (0.2) 25.3 35.8 33.5 
BSA >2 m2 1,843 84.5 (0.4) 33.2 37.6 39.8 
Subgroup Mean RDI,% (SE) RDI <85%,% Dose delay ≥7 days,% Dose reduction ≥15%,% 
Age <50 3,677 88.6 (0.3) 23.6 34.2 31.2 
Age 50-64 4,704 87.6 (0.2) 25.8 35.5 34.0 
Age 65-74 1,687 84.7 (0.5) 32.0 39.7 40.5 
Age ≥75 402 79.4 (1.2) 42.0 46.5 49.2 
BSA ≤2 m2 8,627 87.8 (0.2) 25.3 35.8 33.5 
BSA >2 m2 1,843 84.5 (0.4) 33.2 37.6 39.8 

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P3-12-07.