Optimal timing for pegfilgrastim administration in Japanese breast cancer patients receiving intermediate-risk chemotherapies.

Background Pegfilgrastim is widely used for prophylaxis of febrile neutropenia (FN) in cancer patients receiving chemotherapies. However, the optimal timing of pegfilgrastim administration has not been established. Objective We investigated the effect of the timing of pegfilgrastim administration on the prevention of FN in patients with breast cancer undergoing intermediate-risk chemotherapies. Method We retrospectively analysed the incidence of FN in patients with breast cancer treated at our institution with intermediate-risk chemotherapies and primary or secondary prophylactic pegfilgrastim between 2015 and 2017. The impact of the timing of pegfilgrastim administration on the incidence of FN was evaluated by univariate and multivariate logistic regression analyses. Results Overall, 87 patients received a total of 318 chemotherapy cycles with pegfilgrastim, and 14 patients (16%) experienced FN. In univariate analyses, day 2 pegfilgrastim administration, age of > 65 years, baseline haemoglobin < 12 g/dL, prior history of FN, and presence of recurrent/metastatic disease trended toward an association with FN. Adjustment for these confounding risk factors revealed that day 2 pegfilgrastim administration was associated with a significantly increased risk of FN (odds ratio 11.0, p = 0.009). Conclusion Administrating pegfilgrastim on day 3 or later may prevent FN more effectively among Japanese breast cancer patients receiving intermediate-risk chemotherapies.