Risk models for neutropenia in patients with breast cancer.
Breast cancer is the most common noncutaneous malignancy in women in industrialized countries. Chemotherapy prolongs survival in patients with early-stage breast cancer, and maintaining the chemotherapy dose intensity is crucial for increasing overall survival. Many patients are, however, treated with less than the standard dose intensity because of neutropenia and its complications. Prophylactic colony-stimulating factor (CSF) reduces the incidence and duration of neutropenia, facilitating the delivery of the planned chemotherapy doses. Targeting CSF to only at-risk patients is cost-effective, and predictive models are being investigated and developed to make it possible for clinicians to identify patients who are at highest risk for neutropenic complications. Both conditional risk factors (e.g., the depth of the first-cycle absolute neutrophil count nadir) and unconditional risk factors (e.g., patient age, treatment regimen, and pretreatment blood cell counts) are predictors of neutropenic complications in early-stage breast cancer. Colony-stimulating factor targeted toward high-risk patients starting in the first cycle of chemotherapy may make it possible for full doses of chemotherapy to be administered, thereby maximizing patient benefit. Recent studies of dose-dense chemotherapy regimens with CSF support in early-stage breast cancer have shown improvements in disease-free and overall survival, with less hematologic toxicity than with conventional therapy. These findings could lead to changes in how early-stage breast cancer is managed.