LAUSR

cancer, in particular, is one of the most commonly diagnosed cancers, ranking third in terms of incidence and second in terms of mortality [2]. The incidence rate of colon cancer is highest in Europe, while the incidence rate of rectal cancer is highest in Eastern Asia [2]. The prevalence of colorectal cancer is expected to continue to increase with socioeconomic development, reflecting lifestyle changes, such as increased meat intake, excess body weight, and decreased physical activity [2]. Therefore, the number of patients with colorectal cancer that anesthesiologists encounter in clinical practice are expected to continue to increase. Propofol, a γ-aminobutyric acid (GABA) receptor agonist, is one of the most used intravenous anesthetics due to its rapid induction and recovery rate and lower rate of adverse effects resulting from its favorable pharmacokinetic (PK) and pharmacodynamic (PD) profiles [3]. However, complications, such as hypotension and apnea, do occur. Previously, the Korean Journal of Anesthesiology (KJA) reported that fetal complications resulting from propofol administration occurred in 69.2% of all Korean medical disputes involving anesthesia, especially in cases of diagnostic gastrointestinal endoscopy and esthetic surgery [4]. Moreover, little is known about the PK/PD of propofol in patients with cancer who undergo chemotherapy. Chemotherapeutic drugs can cause hepatorenal or cardiopulmonary side effects and can alter sensitivity to anesthetics as a result of neurotoxic effects, which may cause changes in the PK/PD of propofol [5]. There is also a possibility of increased proliferation or metastasis of cancer cells by propofol through GABA or nuclear factor activation even though propofol is known to have antitumor and protective properties against cancer metastasis [6,7]. Such contradictory results may result from differences not only in cancer cell types but also propofol concentrations [7]. However, anesthesiologists use propofol for sedation and not for its anti-cancer effects. Therefore, it is worth investigating pharmacologic considerations of the effect-site concentration (Ce) of propofol for patients receiving colorectal cancer chemotherapy treatment based on an accurate PK/PD model. Increased knowledge regarding the appropriate amount of propofol to be administered for anesthetic depth in cancer patients will improve patient safety and outcomes. The current edition of the KJA includes a study conducted by Ki et al. [8] investigating the Ce of propofol for loss of verbal contact and loss of consciousness (LOC) using the Modified Observer’s Assessment of Alertness/Sedation scale (MOAA/S) score. During anesthesia induction, the Ce of propofol was increased by target-controlled infusion (TCI) using the Schnider model until the MOAA/S score reached zero. No differences were seen in the Ce of propofol in terms of the MOAA/S score, sedation time, or bispectral index in patients with colorectal cancer receiving chemotherapy. Based on non-linear Received: February 9, 2022 Accepted: February 16, 2022