Investigators recently reported the results of a study suggesting the benefits of identifying subgroups of breast cancer patients at high risk for hospitalization due to febrile neutropenia. Once identified, granulocyte colony-stimulating factor (G-CSF, Neupogen) might be administered prophylactically to these patients to help decrease the incidence of the side effect. The data were presented at the 24th annual San Antonio Breast Cancer Symposium.
"Research has shown that about 20% of early-stage breast cancer patients receive a modified regimen of chemotherapy in terms of lowered dose or treatment delays because they have developed or are at risk for developing negative neutropenic events requiring hospitalization," said Dr. Edgardo Rivera, study author and assistant professor, breast medical oncology, M. D. Anderson Cancer Center in Houston. "This study suggests that physicians can use validated risk models to identify patients who may be at higher risk for chemotherapy-induced neutropenia and then take preventive action to help avoid derailing their chemotherapy."
Chemotherapy Schedule Maintained
The large, open-label, prospective study showed that 95.3% of high-risk patients who received G-CSF vs 79.9% of high-risk patients in the control group were able to receive an effective regimen of chemotherapy on schedule. More than four times as many control patients (20.1%) as G-CSF recipients (4.7%) received a reduced regimen of chemotherapy due to neutropenia. More than twice as many control patients (7.1%) as G-CSF recipients (2.7%) were hospitalized with febrile neutropenia.
The study enrolled 624 stage I-III breast cancer patients who received one of the following adjuvant chemotherapy regimens: doxorubicin(Drug information on doxorubicin)/cyclophosphamide (Cytoxan, Neosar), cyclophosphamide(Drug information on cyclophosphamide)/methotrexate/fluorouracil, or cyclophosphamide/doxorubicin/fluorouracil. Following the Silber risk model, patients whose absolute neutrophil count (ANC) reached a nadir of £ 500/mm³ after the first cycle of chemotherapy were assigned to the high-risk group, and all other patients were assigned to the low-risk group.
High-risk patients received G-CSF for all subsequent cycles of chemotherapy, starting 24 hours after the administration of chemotherapy and continuing for a maximum of 14 days until their ANC reached ³ 10,000/mm³. Low-risk patients received G-CSF in subsequent chemotherapy cycles only if they developed neutropenia with a fever or had a delay in chemotherapy due to neutropenia. The other low-risk patients became the control group.