Exhaled Volatile Organic Compounds in the detection of Colorectal Cancer: A systematic review and meta-analysis

Abstract

Background: There is an apparent need for novel non-invasive colorectal cancer (CRC) screening tests that are more acceptable to patients and can reliably detect CRC or reduce the number of unnecessary colonoscopies performed in cancer-free patients. An emerging number of studies demonstrate the potential value of exhaled volatile organic compounds (VOCs) as a diagnostic and triaging test for CRC. Recognising that these studies might have limited data individually to impact practice on their own, a systematic appraisal and meta-analysis of the published evidence was done to determine whether exhaled VOCs can be used in the detection and screening of CRC.

Methods: Nine electronic databases were searched from inception of the databases until August 15,2020. Quantitative and descriptive data of CRC patients and healthy control (HC) participants who underwent VOCs breath analysis was extracted. In addition where possible, sampling methods, VOCs analytical platforms, processors, and specific breath VOCs biomarkers found in each study were recorded.

Results: 14 articles were included in the systematic review with a total of 491 colorectal patients and 754 healthy control participants (n= 1245). Sub-group meta-analysis was conducted on 9 of those articles and the pooled sensitivity was estimated to be 0.89 (95% CI = 0.80-0.99) whereas specificity was 0.83 (95% CI = 0.74-0.92). Heterogeneity of both pooled sensitivity and specificity was estimated as I2=11.11%.

Conclusions: It is reasonable to deduce that VOCs breath analysis is certainly a field of research that can progress to replace traditional methods within the framework of CRC screening and diagnosis. Although small sample size, inconsistency of data, and different analytical platforms limited this study, the proposed future framework resolves such limitations and standardizes future research. It is predicted that with research progression and standardization, breath analysis can in time be used as an alternative non-invasive mass screening tool prior to colonoscopies. Then, as research advances breath analysis can hold promise not only for screening CRC but for diagnosing and monitoring of CRC.