Predictive factors for severe and febrile neutropenia during docetaxel chemotherapy for castration-resistant prostate cancer

Background: The aim of this study is to identify factors that increase the occurrence of severe neutropenia (SN) and febrile neutropenia (FN) during docetaxel treatment for castration-resistant prostate cancer (CRPC). Methods: We retrospectively reviewed 258 courses during the first three cycles among 95 patients. Docetaxel at a dose of 75 mg/m² was administered every 3 or 4 weeks. Patient background, laboratory data, and bone scan results were collected to assess predictive factors for SN and FN. We defined SN as an absolute neutrophil count (ANC) of <500/mm³ and defined FN as an ANC of <1000/mm³ with a body temperature of >38.3 °C. Results: The mean age of the patients was 72.6 ± 6.4 years and the mean prostate-specific antigen was 135.4 ± 290.9 ng/ml. During the first three courses of treatment, SN occurred in 72.6 % of patients and FN occurred in 9.5 % of patients. Univariate analysis demonstrated that age ≥75 years (p = 0.002), number of comorbidities ≥1.2 (p = 0.008 and p = 0.006) and previous external beam radiation therapy (EBRT) (p = 0.001) were predictive factors for the development of SN or FN. In multivariate analysis, significant predictors of SN or FN were age ≥75 years (hazard ratio [HR] 5.77; p = 0.004) and previous EBRT (HR 14.5; p = 0.012). According to the subgroup analysis dividing SN and FN separately, multivariate analysis also revealed that age ≥75 years and previous EBRT were also significant predictors for developing SN (HR 5.09; p = 0.023, HR 12.7; p = 0.020, respectively) and for developing FN (HR 5.45; p = 0.042, HR 7.72; p = 0.015, respectively). Conclusions: Patients aged ≥75 years and with a history of localized radiation therapy are at higher risk for significant neutropenic events and require closer surveillance.