Objective To investigate the relationship between docetaxel AUC(area under curve) and neutropenia in patients with breast cancer after chemotherapy.

Methods We selected 94 patients with breast cancer who accepted AC sequential T chemotherapy regimen as the first-line treatment from December 2016 to July 2017 in the Affiliated Cancer Hospital of Zhengzhou University. The plasma concentration of docetaxel was detected by latex immunoturbidimetry after the docetaxel continuous infusion. Docetaxel AUC was calculated using nonparametric mixed-effects models. A mathematical model predicting decreased percentage of neutrophils using docetaxel AUC was established.

Results Individual exposure to docetaxel was highly variable (AUC range=0.7-3.9 mg·h/L, mean value=(2.34±0.7)mg·h/L, inter-individual CV=30%). The average AUC for low (0-2) and high grade (3-4) neutropenia were 2.29 and 2.82 mg·h/L, respectively(P=0.003). The model predicting decreased percentage of neutrophils using docetaxel AUC was set as y=-1.8672x²+25.658x-14.92, r=0.643.

Conclusion This research set up a mathematical model to predict decreased percentage of neutrophil, which provide basis for screening high-risk patients who may suffer seriously hematological toxicity and lay a theoretical foundation for individualized dosage based on docetaxel AUC.