G-CSF primary prophylaxis reduces febrile neutropenia and hospitalization, maintains chemo dose in early BC

Using a 4-day, fixed-dose schedule of filgrastim as granulocyte-colony stimulating factor (G-CSF) primary prophylaxis reduces the incidence of febrile neutropenia (FN) and associated hospitalization while maintaining the doses of adjuvant docetaxel and cyclophosphamide (TC) among Chinese women with early breast cancer (BC), a retrospective cohort study in Hong Kong has shown.

“The 4-day [schedule of] G-CSF primary prophylaxis [with filgrastim] may enhance efficacy [of adjuvant chemotherapy] and conserve resources [in public hospitals],” the researchers suggested. [Hong Kong Med J 2022;28:438-446]

The researchers analyzed data from 231 Chinese women with BC treated in Princess Margaret Hospital between November 2007 and October 2013. Within 6–8 weeks after surgery, all patients received intravenous (IV) chemotherapy with docetaxel (75 mg/m²) and cyclophosphamide (600 mg/m²) on day 1 of every 3-week cycle, for four cycles. Dexamethasone and standard antiemetics were administered in each cycle.

From the first cycle of chemotherapy, 83.5 percent of patients (n=193; mean age at diagnosis, 49.8 years; premenopausal, 50.0 percent; invasive ductal carcinoma, 89.5 percent) received G-CSF prophylaxis with subcutaneous filgrastim 30 MU on days 4–7 of each cycle, while the remaining patients (n=38; mean age at diagnosis, 52.1 years; premenopausal, 53.4 percent; invasive ductal carcinoma, 92.2 percent) did not receive any G-CSF prophylaxis. Antibiotics were given to patients with grade 3/4 neutropenia at nadir.

In the entire cohort, 106 patients experienced ≥1 episode of neutropenia. Of these patients, 65.1 percent (n=69/106) developed grade 3/4 neutropenia, and 37.7 percent (n=40/106) developed FN.

Using filgrastim as G-CSF primary prophylaxis reduced rates of FN (14.5 percent vs 31.6 percent; adjusted relative risk [adjRR], 0.45; 95 percent confidence interval [CI], 0.25–0.81) and grade 3/4 neutropenia (24.7 percent vs 57.9 percent; adjRR, 0.43; 95 percent CI, 0.30–0.62) vs no G-CSF prophylaxis.

The study also demonstrated a significantly lower rate of hospitalization for FN in patients who used filgrastim vs those without G-CSF prophylaxis (12.4 percent vs 31.6 percent; p=0.02).

Guidelines of the American Society of Clinical Oncology recommend that patients hospitalized for FN may receive a 5- to 7-day course of broad-spectrum IV antibiotics, with a mean length of hospital stay of >1 week. [J Clin Oncol 2000;18:3558-3585] “[Therefore,] the decreased rate of hospitalization [for FN] can reduce the demands on public hospitals’ resources and reduce the negative impacts on [patients’] quality of life,” the researchers commented. [Hong Kong Med J 2022;28:438-446]

G-CSF primary prophylaxis with filgrastim may help maintain the delivery of TC as adjuvant chemotherapy. The study showed that more patients treated with filgrastim received scheduled doses of TC chemotherapy than those without G-CSF prophylaxis (74.6 percent vs 63.2 percent; p=0.048). A numerically lower proportion of patients in the filgrastim vs no G-CSF prophylaxis group received a >10 percent reduction in dose of docetaxel or cyclophosphamide (docetaxel: 14.0 percent vs 18.4 percent; p=0.326) (cyclophosphamide: 7.3 percent vs 13.2 percent; p=0.066). However, the rate of cycle delay was significantly higher with filgrastim vs no G-CSF prophylaxis (56.5 percent vs 26.3 percent; p=0.001).