Neoadjuvant Chemotherapy Can Decrease the EC50 of Propofol with Effect-Site for Inducing the Loss of Consciousness in Patients with Breast Cancer: A Prospective Study

Abstract

Background: Neoadjuvant chemotherapy has many advantages, including shrinking the tumor volume, reducing the scope of operation, decreasing the degree of trauma and providing evidence for postoperative chemotherapy. However, a certain degree changes of physiological are associated with neoadjuvant chemotherapy. Therefore, we suspect that the sensitive to general agents would be also changed after neoadjuvant chemotherapy. This study aimed to determine the minimum effective concentration represented by the EC50 of propofol for inducing loss of consciousness (LOC). Methods: Sixty patients with breast cancer were enrolled in this study. Patients with or without neoadjuvant chemotherapy were allocated into Group NC and Group C respectively. The concentration of propofol was decided by using the up-down method with an initial concentration of 2.5 µg/mL and concentration change of 0.3µg/mL. An effective induction of LOC was defined as the disappear of eyelash reflex and no response to language stimulation. The Dixon and Massey formula was applied to calculate the EC50 for both groups. Results: The EC50 of propofol for inducing LOC were 4.1µg/mL (95%CI, 3.7-4.5µg/mL) and 3.3µg/mL (95%CI, 2.8-3.8µg/mL). There was significant difference between the two groups. Conclusion: Neoadjuvant chemotherapy can increase the sensitive of propofol, can decrease the EC50 of propofol for inducing of LOC in patients with breast cancer