Volatile organic compounds in exhaled breath: Applications in cancer diagnosis and predicting treatment efficacy

Volatile organic compounds (VOCs) are carbon-based chemicals characterized by high vapor pressure and low boiling points under standard temperature and pressure conditions. VOCs are categorized as exogenous or endogenous, depending on their source. Endogenous VOCs are metabolic byproducts eliminated via respiration. These compounds serve as indicators of human metabolic activity, reflecting differences in tumors compared to normal cell metabolism and the body's response to tumors. Examination of exhaled breath provides a noninvasive approach for assessing metabolic status by comparing VOC levels. Consequently, VOCs are increasingly studied as novel biomarkers for cancer screening, diagnosis, and treatment efficacy prediction. This review outlines VOC production mechanisms, their presence in tumor types, detection methodologies, and their implications for tumor screening, diagnosis, and prognosis. Nonetheless, challenges remain in the utilization of VOCs for cancer diagnosis and predicting treatment outcomes. Furthermore, this review discusses unresolved issues requiring attention to improve malignant tumor assessment, providing insights into their diagnosis, treatment, and prognosis.