Relative dose intensity (RDI) assessment in an academic center.

Abstract

139 Background: Patients with early breast cancer treated in the adjuvant setting realize maximum benefit as to disease- free and overall survival when they receive their full planned dose of chemotherapy. Due to the aggressive treatment regimens, patients are at increased risk of dose delays and reductions, which result in reduced RDI. Studies have shown that at RDI < 85%, treatment outcomes are compromised. We sought to calculate the RDI attained in our breast cancer clinic and identify factors contributing to decreased RDI. Methods: We retrospectively reviewed records of 383 patients treated between January 2008 and December 2009. Treatment blocks were reviewed separately to better identify contributing factors to decreased RDI. Regimens were dose-dense doxorubicin and cyclophosphamide (ddAC), dd-paclitaxel (ddT), paclitaxel and trastuzumab (TH), and TH post ddAC. G-CSF support was noted when present. Dose reductions and dose delays (in days) with reason(s) were recorded for patients with RDI < 85%. Patients who switched care or regimen were excluded from this study. Results: Of the 383 patients, 150 received ddAC; 101 ddT; 67 TH and 65 TH post ddAC. Of these, the percentage of patients with RDI < 85% was 10.4%. RDI was <85% in 8.7%, 6.9%, 14.9%, and 15.4% in the ddAC, ddT, TH, and TH post ddAC regimens, respectively. The major impediments were neutropenia in the anthracycline containing regimen, neuropathy with taxanes, and cardiotoxicity with trastuzumab. No dose delays were seen for administrative issues. Conclusions: Our results show that 10.4% of treated patients had RDI < 85%. These results were superior when compared to historic data for same regimens. Major reasons for decreased RDI were neutropenia, neuropathy, and cardiotoxicity. Improving risk assessment of neutropenia before initiating treatment could improve RDI in this patient population. Prophylaxis with vitamin B6 may help reduce incidence of neuropathy. Efforts to assure on-schedule treatments should be maintained. This includes comprehensive paramedical support to overcome any hurdles to on-time treatment. Proper education of patients on the importance of RDI can increase awareness of the value of cooperating with the provider and encourage them to persevere with the treatment.