Efficacy and safety of same-day versus next-day administration of PEG-rhG-CSF for the prophylaxis of chemotherapy-induced neutropenia and febrile neutropenia in patients with breast cancer: a retrospective cohort study.

Objectives: Polyethylene glycol recombinant human granulocyte colony-stimulating factors (PEG-rhG-CSFs) are used to prevent or treat chemotherapy-induced neutropenia (CIN) and febrile neutropenia (FN). This study aimed to compare the efficacy and safety of same-day versus next-day PEG-rhG-CSF administration following chemotherapy and the effects of 3 mg versus 6 mg dosages.

Methods: We retrospectively analyzed cohort data of patients with breast cancer who underwent chemotherapy and received PEG-rhG-CSF either within 24 h (same-day group) or 24 h (next-day group) after chemotherapy. The incidences of CIN and FN were assessed in each chemotherapy cycle between the two groups. The primary endpoint was the incidence of FN in the first cycle and throughout all cycles. The secondary endpoints included the incidences of various grades of CIN (CIN1-CIN4), antibiotic use, chemotherapy regimen modifications, and overall safety.

Results: Among the 2385 chemotherapy cycles with prophylactic PEG-rhG-CSF in 620 patients, 798 and 1587 cycleswere in the same-day and next-day group, respectively. No statistically significant differences were observed in the incidence of FN in the first cycle or across all cycles, CIN1-4, or adverse reactions between the two groups. However, the same-day group exhibited significantly higher rates of antibiotic use (2.88% vs. 0.42%, p = .03) and chemotherapy regimen modification (4.68% vs. 1.45%, p < .001). Subgroup analysis indicated no differences in outcomes for the 6 mg dosage, but a significantly lower incidence of CIN was observed in the same-day group receiving 3 mg (p = .025).

Conclusions: These findings suggest that same-day administration of PEG-rhG-CSF is as effective and safe as next-day administration in preventing FN and CIN during chemotherapy.