Impact of chemotherapy dose-related factors on survival in breast cancer patients treated with adjuvant anthracycline-based chemotherapy

Abstract

668 Background: The relationship between chemotherapy (CT) dose intensity and patient (pt) outcome in the management of early stage breast cancer (EBC) is still controversial. Although randomised clinical trials have provided evidence that supports the delivery of full standard doses of CT on schedule, precise thresholds for CT dose-related factors and their impact on survival-related endpoints have not yet been fully defined. The objective of this project is to assess the impact of CT dose-related factors on event-free and overall survival in a large group of EBC pts treated with anthracycline-based chemotherapy. Methods: A total of 1056 EBC (stage I-II-IIIA) cases diagnosed and treated from January 1980 to December 2000 were retrospectively studied. All of them received adjuvant anthracycline non-taxanes-based CT. Consecutive charts from 793 pts that were fully completed were included in the analysis. Survival-related endpoints were analysed through Kaplan-Meier estimates, log-rank tests, and Cox proportional hazards models. Results: With a median follow-up of 10.0 years, pts exposed to either > 2 cycle-delay (delay at any cycle defined as ≥ 3 days vs. plan), or ≥ 15 day-delay across the whole CT regimen, or < 95% relative dose intensity (RDI) showed significantly worse 10-year Event-Free Survival (EFS) and Overall Survival (OS) as compared to pts with no dose delay/reduction (data shown below). Controlling for age at diagnosis, disease stage, histological grade, menopausal status and year of treatment did not modify these results. Conclusions: Based on this preliminary analysis, CT dose delays and reductions in EBC pts treated with adjuvant anthracycline-based regimens have a significantly negative impact on EFS and OS. [Table: see text] No significant financial relationships to disclose.