Recent studies report that prophylactic PEG‐G‐CSF not only reduces FN incidences,12 but was able to maintain dose intensity and improve the prognosis in adjuvant treatments for breast cancer.13 In our study, the use of PEG‐G‐CSF might have influenced better efficacy, especially in primary prophylactic PEG‐G‐CSF, which is consistent with a previous study.13 Therefore, primary prophylactic PEG‐G‐CSF is considered an important option for better efficacy and safety, but appropriate dose reduction at the initial course and after the initial course is needed in some cases. This evidence concerns the gene CSF3 and breast cancer.