Background: Data suggests that males experience less toxicity and poorer survival than females treated for Ewing's sarcoma. We instituted an intra-patient dose escalation (DE) policy with Vincristine/Doxorubicin/Cyclophosphamide (VDC) alternating with Ifosfamide/Etoposide (IE) based on hematological nadirs and report its feasibility and safety.
Methods: A retrospective review of adherence to DE guidelines and toxicities was conducted for patients who received DE with VDC/IE over 3 years at a single cancer center. Absolute neutrophil counts (ANC) was collected on days 8, 12 and 15 for cycles 1-6. DE of 10%/cycle was applied if ANC > 1.5×109/L and platelet > 100×109/L on all blood results. The primary endpoint was the proportion of patients who received appropriate DE. The secondary endpoint was to assess morbidity, changes in hematologic nadirs between gender and age and a comparison with a prior cohort of ESFT patients who did not receive DE. Gender comparisons were assessed via independent 2-sample t-tests assuming unequal variances. Within cycle changes in hematologic nadirs were assessed using repeated measures ANOVA. Relapse free survival and overall survival (OS) curves were estimated using the Kaplan-Meier method.
Results: 23 patients were identified (mean age: 27; range 17-54). 91 decisions for DE were made (1 decision excluded because of progressive disease) with 90% concordance with guidelines. No adverse outcomes occurred as a result of the inappropriate escalation. Grade 3/4 febrile neutropenia (FN) during VDC and IE was 26.1% (6/23 patients) and 17.4% respectively with no difference for those who were DE. Males were less neutropenic after C1 and C3 of VDC compared to females (P-value C1 = 0.003; C3 = 0.005). VDC was associated with greater neutropenia on day 8 whereas IE had greater neutropenia on day 12 (P-value <0.001). During VDC, a non statistical difference in neutropenia was seen for individuals aged 15-25 (n = 13) compared with older individuals (P-value = 0.09). OS comparison for those with localized disease with a prior cohort who were not DE showed similar outcomes (P-value = 0.37).
Conclusions: DE is deliverable without increased adverse outcomes. Males have less myelosuppression during VDC, and should be especially considered for DE.