Development of a Nomogram for Predicting Severe Neutropenia Associated With Docetaxel-Based Chemotherapy in Patients With Castration-Resistant Prostate Cancer

Background Neutropenia is a major adverse event of docetaxel-based chemotherapy. The present study was undertaken to evaluate the incidence of neutropenia and to develop a nomogram for predicting Grade 4 neutropenia during the first cycle of docetaxel-based chemotherapy in patients with castration-resistant prostate cancer (CRPC). Patients and Methods This study included 112 patients with CRPC treated with docetaxel-based systemic chemotherapy. We evaluated the incidence and risk factors for Grade 4 neutropenia in the first cycle of chemotherapy. Results Sixty-two of 112 patients (55.4%) developed Grade 4 neutropenia in the first cycle of docetaxel-based chemotherapy. There were significant differences in age, baseline white blood cell count, and baseline neutrophil count between patients with non-Grade 4 neutropenia and those with Grade 4 neutropenia in univariate analyses. The serum prostate-specific antigen level, hemoglobin level, creatinine, albumin, Eastern Cooperative Oncology Group performance status, metastatic sites, extent of disease, and history of external beam radiotherapy to the prostate were not significantly different between the 2 groups. Multivariate logistic regression analysis showed that age (odds ratio [OR], 1.08; P = .019) and baseline neutrophil counts (OR, 0.79; P = .045) were significant independent risk factors for severe neutropenia. A nomogram and a calibration plot on the basis of these results were developed from a multivariate logistic regression analysis to predict the probability of Grade 4 neutropenia. Conclusion Age and baseline neutrophil counts were significant independent risk factors for Grade 4 neutropenia. The nomogram to predict it provides useful information for the management of patients with CRPC treated with docetaxel chemotherapy.