Abstract P1-15-04: The relationship of relative dose intensity and supportive care to febrile neutropenia rates in patients with early stage breast cancer receiving chemotherapy: a prospective cohort study of chemotherapy-associated toxicity

Abstract

Abstract Background: Febrile neutropenia (FN) represents a major dose-limiting toxicity of cancer chemotherapy resulting in considerable morbidity, mortality, and cost. Patients have the highest risk of the initial neutropenic event in cycle 1 when most patients receive full dose chemotherapy. This study evaluates time course of neutropenic events in patients receiving chemotherapy for early-stage breast cancer (ESBC) and supportive care interventions that modify FN risk in ESBC patients treated in actual oncology practice. Methods: A prospective cohort study of adult cancer patients with solid tumors or lymphoma starting a chemotherapy regimen was conducted at 115 U.S. sites. Toxicities associated with chemotherapy were recorded in up to 4 cycles including severe neutropenia (SN), FN, and infection. Documented clinical interventions included reductions in chemotherapy relative dose intensity (RDI), the use of colony-stimulating factors (CSFs), and antibiotics. Results: A total of 1202 ESBC patients starting chemotherapy were analyzed, of which 1154, 1099, and 896 reached the midcycle of cycles 2, 3, and 4, respectively. While the majority of neutropenic and infection events occurred in cycle 1, decreasing rates of FN and infection in later cycles correlated with increasing reductions in dose intensity and increased use of CSFs and antibiotics. The overall risk of FN in all patients combined was 16.3 %. It reached 21.1% for patients who started with planned RDI≥85% and without primary CSF prophylaxis. There was no significant difference in FN rates by menopausal status or hormone receptors. Conclusions: While the risk of neutropenic complications is highest during the first cycle of chemotherapy, reductions in neutropenic events during subsequent cycles are associated with reduced chemotherapy dose intensity or increased use of supportive care measures. Nevertheless, the cumulative risk of neutropenic events remains high in ESBC patients receiving full dose chemotherapy without prophylactic measures overall and across menopausal and hormone receptor subgroups. Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P1-15-04.