Early detection and follow‐up of colorectal neoplasia based on faecal volatile organic compounds

Abstract

Aim Early detection and removal of colorectal cancer (CRC) and advanced adenomas (AAs) decreases the incidence of and mortality from the disease. We aimed to evaluate the potential of faecal volatile organic compounds (VOCs) for detection and follow-up of colorectal adenoma using advanced electronic nose technology. Method This was a prospective multi-centre case-control cohort including two district hospitals and one tertiary referral hospital. Patients undergoing colonoscopy were instructed to collect a faecal sample prior to bowel cleansing and were included in the study when CRC, AAs, large adenomas (LAs; 0.5-1.0 cm), small adenomas (SAs; 0.1-0.5 cm) or no endoscopic abnormalities (controls) were observed. Patients undergoing polypectomy and controls were asked for a second sample after 3 months. Faecal VOCs were measured with gas chromatography-ion mobility spectrometry. Random forest, support vector machine, Gaussian process and neural net classification were used to evaluate accuracy. Results In total, 14 patients with CRC, 64 with AAs, 69 with LAs, 127 with SAs and 227 controls were included. A second sample was collected from 32 polypectomy patients and 32 controls. Faecal VOCs discriminated CRC and adenomas from control [AUC (95% CI): CRC vs control 0.96 (0.89-1); AA vs control 0.96 (0.93-1); LA vs control 0.96 (0.92-0.99); SA vs control 0.96 (0.94-0.99)]. There were no significant differences between CRC and adenoma groups. Patients with adenomas and controls were discriminated prior to polypectomy, whereas 3 months after polypectomy VOC profiles were similar [T0 adenoma vs control 0.98 (0.95-1); T1 adenoma vs control 0.55 (0.40-0.69)]. Conclusions Faecal VOC profiles may be useful for early detection of CRC and adenomas and the timing of polyp surveillance as polypectomy led to a normalization of the VOC profile.

Are Volatile Organic Compounds Accurate Markers in the Assessment of Colorectal Cancer and Inflammatory Bowel Diseases? A Review

“…Only two studies used GC-MS and were able to identify specific VOCs [ 49 , 50 ]. Bosch et al [ 50 ] reported that fecal VOCs could discriminate CRC patients from the controls with an AUC of 0.96.…”

Towards Novel Non-Invasive Colorectal Cancer Screening Methods: A Comprehensive Review

“…On one hand, Gas chromatography-mass spectrometry (GC-MS), which is a chemical analytical technique, is considered the ongoing gold standard in VOC detection [52], but on the other hand, VOC sensors are getting more and more relevance because they are inexpensive, often portable, and easy to use [109]. This is why findings such as the ones listed in Table S7 (Supplementary material) could represent the next frontier for large population-based screening programs [50][51][52][53][54][55][56][57][58].…”

“…When looking at these results, we should notice some limitations: Current studies are limited to case control and cohort studies, not taking into consideration a real screening setting. Also, due to their complex interaction in the gut, external factors such as diet and medications play a role in VOCs profiling [50] and they are often not deeply analysed before proceeding into the CRC-control differentiation. Nonetheless, these studies highlight the potential of FAIMS in analyzing Urinary VOCs for CRC detection.…”

“…The following are available online at https://www.mdpi.com/article/10.3 390/cancers13081820/s1, Table S1: Efficacy of SEPT9 methylation assays based tests for CRC detection, Table S2: Summary of methylated genes panels feasible for CRC detection, Table S3: miRNAs as CRC biomarkers, Table S4: piRNAs as CRC biomarkers, Table S5: t-M2-PK as CRC screening tool, Table S6: Gut microbiota as CRC screening tool, Table S7: Stool volatile organic compounds (VOCs) based CRC test: chemical analytical and pattern recognition techniques. References [16,17,[19][20][21][22][23][27][28][29][30][31][32][33][34][35][43][44][45][46][47][48][49][50][52][53][54][55][56][57] are cited in the Supplementary Materials.…”

Urinary Volatiles and Chemical Characterisation for the Non-invasive Detection of Prostate and Bladder Cancers 

“…GC-IMS (Gas Chromatography-Ion Mobility Spectrometry) is one such technique, it provides high sensitivity and selectivity, and the GC-IMS can be created in a portable form factor and can use nitrogen or air as the carrier gas. Our group has reported the use of this method with a range of different diseases 28,29 .…”