P173 Exploration of the use of urinary volatile organic compounds in comparison to alpha fetoprotein

Abstract

Introduction Alpha fetoprotein (AFP) is no longer recommended by for routine use in hepatocellular carcinoma (HCC) surveillance. On the other hand, the analysis of volatile organic compounds (VOCs) is emerging in medical diagnostics for variety of diseases. VOCs are organic chemicals that can evaporate from liquid to gases. VOCs emerge from the cell membranes, following cellular damage, then find their way into the systemic circulation and finally excreted in the urine. Detection of urinary VOCs is of low cost (≤ £30/sample). We compared AFP to chemical signatures of the urinary VOCs in HCC patients. Methods Ethical approval was granted by Coventry and Warwickshire research ethics committee (09/H1211/38). We collected 5 mls of urine from 31 HCC cases from January to June 2019. Male to female ratio was 5:1 and mean age was 72 years. Urine samples were left to freeze within 2 hours to –80 oC. Analysis of the samples completed at the end of recruitment. Prior to analysis samples were left to thaw in a water bath at 50°C for 1 h. Urine was then placed into a Falcon conical centrifuge tube 50- mL with a modified cap with two slots to allow two solid phase microextraction tabs to be inserted to absorb gases from the head space of the samples. These tabs were analysed using an array of eight metal oxide gas sensors. Responses from the gas sensors to the urinary vapours were captured over a period of 180 seconds, then digitized and stored by computer software. The receiver operating characteristics (ROC) curves were calculated using established algorithm that was applied to different classes of data generated from an artificial radial basis function network (RBFN). Results The sensitivity of AFP alone in our study for HCC detection was 54.8% (raised AFP >10 kU/L in only 17 cases). When comparing urinary VOCs to AFP, they showed good discrimination in diagnosis of HCC. The sensitivity for detection of HCC with normal AFP was 68% (ROC Curve Area was 0.68, SE 0.06, 95% CI 0.54 to 0.81 and P Conclusion Urinary VOCs could have a potential role in screening and surveillance of HCC. It is an attractive tool because it is non-invasive and has a low cost. Further validation from studies with larger sample size is required.