Abstract
1065 Background: The consequences of reducing chemotherapy dose intensity might be extensive, potentially affecting short- and long-term outcomes as well as patient quality of life, the dose and schedule are of central concern in the delivery of chemotherapy. Methods: This statistical analysis was based on individual subject data of 934 patients (pts) obtained from the following prospective, open-label, randomised phase III trials in metastatic breast cancer that recruited between 1996 and 2005 investigating an anthracycline/taxane based first-line chemotherapy: CECOG trial, AGO-Mamma-1 and AGO-Mamma-3 trial. The primary objective of the analysis was to evaluate the influence of RTDI on progression free survival (PFS) in different predefined binary RTDI cuts from 75% to 95% with an interval at every 5%. Relative total dose intensity (RTDI) is the ratio of actual total dose intensity and planned total dose intensity, expressed as a percentage. RTDI quantifies dose reductions and delays, as well as premature discontinuations in treatment. Results: Overall cuts pts with higher RTDI had a shorter PFS compared to those with lower RTDI. A time dependent term for low RTDI was included in the analysis and showed the opposite effect after approximately 60 weeks. The overall median PFS was 39 weeks. Analysis of the Kaplan-Meier curve identified many early events in patients with high RTDI. We hypothesized that patients with a primary progression (PP) who have by definition a high RTDI were responsible for this effect. The PFS excluding 114 patients with PP showed no difference for patients with high compared to those with low RTDI. The median overall survival (OS) for the whole study population was 98 weeks. Excluding patients with PP, the median OS was 118 weeks (95% CI [103–136]) for those with RTDI ≥ 85% versus 96 weeks (95% CI [83–119]) if RTDI was < 85% (log-rank p = 0.0086). The results were comparable across other cut levels. Conclusions: Maintaining RTDI in patients not experiencing PP might have significant impact on overall survival. No significant financial relationships to disclose.
Highlights
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
Overall higher RTDI was correlated with a shorter time to disease progression (TTDP)
It was explained by the fact that patients with primary disease progression (PDP) do have a high RTDI per definition
Summary
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. Therapy of metastatic breast cancer (MBC) has improved over the last decades probably due to sequential systemic treatment in multiple lines [1]. A retrospective analysis of community practice data from records of 20,799 patients with early breast cancer (EBC) between 1997-2000 found that the average actual RTDI was 79% [2]. In this analysis, 56% of patients with EBC received less than 85% RTDI. Significant dose reductions and treatment delays are common clinical practice in the management of patients with primary breast cancer. Even more alarming picture might be observed in patients with MBC, where dose delays and reductions are common methods of reducing the toxicities and maintain the QoL
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