Granulocyte colony-stimulating factors (G-CSFs) reduce febrile neutropaenia (FN) incidence but may be used inconsistently in current practice (CP). This study compared the efficacy of pegfilgrastim primary prophylaxis (PPP) with CP neutropaenia management in breast cancer. Individual patient data (N=2282) from 11 clinical trials and observational studies using chemotherapy regimens with > or =15% FN risk and PPP (6 mg, all cycles) or CP (no G-CSF or any cycle G-CSF/pegfilgrastim) were included in an integrated analysis. Most patients received docetaxel-containing regimens. A generalised linear mixed model was fitted (N=2210). Neutropaenia prophylaxis (PPP versus CP), age and disease stage influenced the incidence of FN. Overall, FN was less frequent with PPP than with CP (odds ratio [OR]: 0.124; 95% confidence interval [CI]: 0.08, 0.194; P<0.0001). Odds for cycle 1 FN, dose reductions > or =15% and FN-related hospitalisation were also significantly lower with PPP. These data support PPP in breast cancer patients receiving chemotherapy with moderately high/high FN risk.