Utility of serum interleukin-18 (IL-18) as a tumour marker in gastric cancer

Introduction: Gastric cancer (GC) is the fourth most prevailing cancer globally, attributing to more than 70% of cases in developing countries. Protein cancer biomarkers, such as CEA, CA- 125, AFP and PSA, are clinically helpful diagnostic tools, but they have low sensitivity and specificity for GC. Hence, it is essential to discover better markers for GC diagnosis. Interleukin-18 (IL-18) is the member of Interleukin-1 family. It is hypothesized to be a potent inhibitor of gastric acid secretion, leading to gastric atrophy and causing an increased risk of GC. This study was to evaluate the association between the serum IL-18 in GC. Methodology: We included cases who underwent UGI Scopy and were proven to have GC histopathologically. The patients who presented to the out-patient who underwent UGI scopy and was found to have no growth were selected as controls. Twenty-eight cases and 84 control sample sizes were derived from nMaster V2. Blood samples from patients and controls were collected, and serum IL-18 levels were estimated using a solid-phase sandwich ELISA method. Results: We found that the cut-off value of serum IL-18 was 85.59 pg/ml, had a sensitivity of 63.1% and specificity of 57.1%, with a positive predictive value of 81.5% and a negative predictive value of 34% in diagnosing GC. The study plotted the receiver operating characteristic curve against IL-18 for sensitivity and specificity. Statistically, we found through the Area Under the Curve (AUC) that the rise in serum IL-18 levels was a poor indicator of GC with a p-value of 0.078. Conclusion: Statistically, a cut-off of 85.59pg/ml showed good sensitivity and specificity; however, the probability was insignificant, suggesting that IL-18 may not be of diagnostic importance. Studies with a larger sample size are required to further probe into the usefulness of estimating IL-18 in GC.