P5-18-11: Incidence of Chemotherapy Dose Reductions and Dose Delays, and Reduced Chemotherapy Dose Intensity in Early Stage Breast Cancer.

Abstract

Abstract Background: Chemotherapy is widely used to treat early stage breast cancer (ESBC). Dose reductions and dose delays–e.g., due to advanced age or severe/febrile neutropenia–are generally believed to increase risk of disease progression and reduce survival. Little is known about incidence of chemotherapy dose reductions and dose delays among women with ESBC in clinical practice. Methods: This study employed a retrospective cohort design and electronic medical records from over 60 community oncology clinics in more than 20 states (2004-2010). Study population included adult women who received myelosuppressive chemotherapy for ESBC (stages I-IIIA). For each such woman, each unique cycle of chemotherapy within their first observed course was identified. Incidences of chemotherapy dose delays (≥7 days for any drug in ≥1 cycles), chemotherapy dose reductions (≥15% for any drug in ≥1 cycles), and low relative chemotherapy dose intensity (<85% over the course) – relative to physician-reported planned chemotherapy administration – were descriptively analyzed for the seven most frequently observed regimens among subjects. Results: 2,350 women received seven most frequently observed regimens (80% of study population); mean age – across regimens – ranged from 51–56 years, and 31–94% received primary prophylaxis against severe/febrile neutropenia with a colony-stimulating factor. Incidence of dose reductions ranged from 17–48%, and dose delays, from 24–45%. Overall mean relative dose intensity (RDI) ranged from 80%-99%, and 17–50% of subjects received RDI <85%; mean RDI among those with low RDI ranged from 40%-67%. Discussion: Chemotherapy dose delays and dose reductions are common in ESBC, among those receiving dose-dense as well as conventional regimens. Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P5-18-11.