Analysis of the effects of microbiomerelated confounding factors on the reproducibility of the volatolomic test

Background : Volatile organic compound (VOC) testing in breath has a potential in gastric cancer (GC) detection. Our objective was to assess the reproducibility of VOCs in GC, and the effects of conditions modifying gut microbiome on the test results. Methods : Ten patients with GC were sampled for VOC over 3 consecutive days; 17 patients were sampled before and atier H. pylori eradicatiyon therapy combined with a yeast probiotic, but 61 patients – before and atier bowel cleansing (interventions affecting the microbiome). The samples were analyzed by: (1) gas chromatography linked to mass spectrometry (GC- MS), applying non- parametric Wilcoxon test (level of significance p < 0.05); (2) by cross- reactive nanoarrays combined with patiern recognition. Discriminant function analysis (DFA) was used to build the classification models; and leaveone- out cross- validation analysis was used to classify the findings. Results : Exhaled VOCs profiles were stable for GC patients over a 3- day period. Alpha pinene. [...].