Abstract: Objective To investigate the diagnostic values of L⁃carnitine and acetyl⁃carnitine (ACar 2: 0) in esophageal squamous cell carcinoma (ESCC). Methods The serum of 31 ESCC patients from Guangxi Medical University Cancer Hospital from April 2022 to October 2022 were collected and 30 healthy volunteers during the same period were recruited. Ultra⁃high performance liquid chromatography and quadrupole time⁃of⁃flight mass spectrometry (UHPLC⁃QTOF⁃MS/MS) was used to targetedly analyze the serum metabolic changes of L⁃carnitine and acetyl⁃carnitine. The diagnostic efficiency was evaluated by receiver operating characteristic (ROC) curve. Results Compared with the case in healthy controls, there was no significant difference in serum carnitine level in ESCC patients (P=0.149), and the levels of two acetyl⁃carnitine isomers (ACar 2∶0 isomer1 and ACar 2∶0 isomer 2) were increased (both P<0.001). Multivariable analysis showed that ACar 2∶0 isomer 1 >0.0163 μmol/L (OR=19.456, 95%CI: 1.971-192.104, P=0.011) and ACar 2∶0 isomer 2 >0.0148 μmol/L (OR=7.720, 95%CI: 1.047-56.915, P=0.045) were the risk factors for ESCC, while L⁃carnitine (OR=1.310, 95%CI: 0.051-33.951, P=0.871) was not significantly associated with ESCC. The two acetyl⁃carnitine isomers had a good ability to distinguish between ESCC and healthy controls. The area under curve (AUC), sensitivity and specificity of ACar 2∶0 isomer 1 in the diagnosis of ESCC were 0.957, 0.900 and 0.862, respectively. The AUC, sensitivity and specificity of ACar 2∶0 isomer 2 in the diagnosis of ESCC were 0.901, 0.867 and 0.821, respectively. The AUC, sensitivity and specificity of combining ACar 2∶0 isomer 1 and ACar 2∶0 isomer 2 in the diagnosis of ESCC were 0.952, 0.867 and 0.889, respectively. Conclusions Serum acetylcarnitine level increases in ESCC, showing a good efficacy in the diagnosis of ESCC, and may become a potential diagnostic marker.

Key words: Esophageal squamous cell carcinoma, Acetyl-carnitine, Targeted metabolomics, Diagnosis