Open Access Research article

Evaluating the impact of Relative Total Dose Intensity (RTDI) on patients' short and long-term outcome in taxane- and anthracycline-based chemotherapy of metastatic breast cancer- a pooled analysis

Sibylle Loibl1*, Tomas Skacel23, Valentina Nekljudova1, Hans Joachim Lück4, Matthias Schwenkglenks5, Thomas Brodowicz6, Christoph Zielinski6 and Gunter von Minckwitz1

Author Affiliations

1 German Breast Group, Neu-Isenburg, Germany

2 First Faculty of Medicine, Clinical Department of Haematology, Charles University Prague, Czech Republic

3 Amgen Europe, Zug, Switzerland

4 Gynaecologic Oncology Clinic, Hannover, Germany

5 European Center of Pharmaceutical Medicine, University of Basel, Switzerland

6 Clinical Division of Oncology, General Hospital and Central European Cooperative Oncology Group (CECOG), Medical University, Vienna, Austria

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BMC Cancer 2011, 11:131  doi:10.1186/1471-2407-11-131

Published: 12 April 2011

Abstract

Background

Chemotherapy dose delay and/or reduction lower relative total dose intensity (RTDI) and may affect short- and long-term outcome of metastatic breast cancer (MBC) patients.

Methods

Based on 933 individual patients' data of from 3 randomized MBC trials using an anthracycline and taxane we examined the impact of RTDI on efficacy and determined the lowest optimal RTDI for MBC patients.

Results

Median time to disease progression (TTDP) and overall survival (OS) of all patients were 39 and 98 weeks. Overall higher RTDI was correlated with a shorter TTDP (log-rank p = 0.0525 for 85% RTDI cut-off). Proportional hazards assumption was violated, there was an early drop in the TTDP-curve for the high RTDI group. It was explained by the fact that patients with primary disease progression (PDP) do have a high RTDI per definition. Excluding those 114 patients with PDP the negative correlation between RTDI and TTDP vanished. However, non-PDP patients with RTDI-cut-off levels <85% showed a shorter OS than patients with higher RTDI levels (p = 0.0086).

Conclusions

Optimizing RTDI above 85% appears to improve long-term outcome of MBC patients receiving first-line chemotherapy. Lowering RTDI had no negative influence on short term outcome like OR and TTDP.