Supersulfide metabolome of exhaled breath condensate for diagnostic biomarkers of esophageal cancer.
Authors: Asamitsu Seji , Ozawa Yohei , Ogata Seiryo , Okamoto Hiroshi , Yoshitake Jun , Matsunaga Tetsuro , Taniyama Yusuke , Sato Chiaki , Ishida Hirotaka , Abe Takaaki , Akaike Takaaki , Kamei Takashi 
Published: June 2024

e15027 Background: The early estimate and detection of esophageal cancer (EC) is essentially required for continuous esophagogastroduodenoscopy and histopathological diagnosis. However, endoscopic examination is sometimes invasive, which may cause somehow limited clinical application and compliance. Also, the traditional blood tumor marker is unsuitable for a cancer screening. In recent years, the energy production by sulfur respiration in hypoxic environments in cancer tissues is getting spotlighted in tumor biology. The current study is aimed to evaluate usefulness of sulfur containing compounds as new biomarkers for EC by using blood samples and exhaled breath condensate (EBC) that can be readily obtained in a non-invasive fashion. Methods: Fifty EC patients were included in the study between June 2021 and September 2021. EBC and plasma samples were collected before starting any medicinal remedy including medication, chemotherapy, radiation, surgery, and endoscopic and dentistry maneuvers. Thirty healthy controls were recruited if they did not have any cancer history, surgery and aged over 50s preferred age for esophageal cancer. All samples were stored at -80℃ immediately after appropriate preparation until the following inspection. Then, sulfur metabolome analysis using LC-MS/MS was performed to see the difference of metabolic profile between the two groups. We used Student t tests for comparing two groups, and one -way ANOVA test for more than two groups, with significance set at P<0.05. To evaluate the diagnostic value of some metabolites, ROC curves and the AUC were calculated. Results: The supersulfide metabolic profiles were remarkably different between EC patients and controls. Especially, cysteine persulfide (CysSSH) was significantly increased in both EBC and plasma of the EC patients. The sensitivity and specificity of CysSSH in EBC were 60% and 96%, respectively, with an AUC of 0.71. The sensitivity and specificity of CysSSH in plasma were 49% and 96%, respectively, with an AUC of 0.73. In addition, homocysteine persulfide (HomoCysSSH) in plasma showed more significant difference than CysSSH and was able to distinguish EC patients from healthy subjects with AUC of 0.93 (sensitivity, 89%; specificity, 96%). The level of HomoCysSSH was correlated with that of CysSSH in EBC. The subgroup analysis for histological subtypes and tumor progression showed that both two metabolites were increased in EC patients regardless of histological type and disease’ progression. In particular, the amount of homoCysSSH in plasma was statistically higher in early-stage EC than that of controls (p<0.0001). Conclusions: Supersulfides like CysSSH and HomoCysSSH could be potential biomarkers for detecting EC. Cysteine persulfide from EBC may serve as a valuable non-invasive biomarker with similar detectable ability compared with several biomarkers of blood samples that are currently reported.