P81 Bedside measurement of exhaled breath condensate hydrogen peroxide differentiates lung cancer and interstitial lung disease from healthy controls

Introduction and objectivesLung Cancer and Interstitial Lung Disease (ILD) are prevalent conditions that have a poor prognosis, often due to a delay in diagnosis which limits management options. Inflammation and oxidative stress are processes that occur early in the course of disease within both of these conditions, with hydrogen peroxide one by-product of these inflammatory processes. Using a novel handheld device (Inflammacheck™), we sought to determine whether bedside measurement of Hydrogen Peroxide in Exhaled Breath Condensate (EBC H2O2) could differentiate patients with lung cancer or ILD from healthy controls.Methods16 patients with a confirmed diagnosis of lung cancer and 20 patients with ILD were recruited from outpatient clinics in secondary care, alongside 25 healthy participants. Participants completed two measurements of EBC H2O2 using the Inflammacheck™ device. Data including recent radiology, spirometry and blood tests were also recorded, along with disease-specific information including performance status, and cancer stage or ILD GAP (Gender, Age, Physiology) score.ResultsEBC H2O2 levels were significantly increased in lung cancer patients (mean 3.21μM, SD ±1.52) compared to healthy controls (mean 1.56μM, SD ±1.70) (p=0.03). EBC H2O2 levels were also significantly increased in ILD patients (mean 3.26μM, SD ±1.15) compared to healthy controls (p=0.001). Sensitivity and specificity analysis demonstrated an excellent ability of EBC H2O2 to differentiate between patients with cancer (ROC 0.837, CI 0.68 to 0.99) or patients with ILD (ROC 0.817, CI 0.67 to 0.97) and healthy controls.There was no significant difference in EBC H2O2 levels across TNM stage, overall stage or histological type for lung cancer patients (p>0.05), or between ILD classification or GAP index in ILD patients (p>0.05).ConclusionWe have demonstrated that levels of exhaled breath condensate hydrogen peroxide are significantly elevated in patients with lung cancer and ILD compared with healthy controls. Bedside measurement of EBC H2O2 could present a new tool in the diagnosis of lung cancer and ILD. Further studies with larger patient cohorts are required to confirm this observation, and clarify the potential role of EBC H2O2 in clinical care.