Detection of gas components as a novel diagnostic method for colorectal cancer

Background: The fecal occult blood test (FOBT) is widely accepted as the most economic and non-invasive screening method for colorectal cancer (CRC). However, the FOBT is inconvenient because it requires a fecal sample and shows limited accuracy. Alternatively, we hypothesized that fecal gas compounds from bowel movements may be a non-invasive biomarker for CRC. Methods: Gas compounds were collected from the bowel movements of 30 patients with CRC and from 26 healthy controls. The patient group comprised 17 males and 13 females, and the average age was 68 years. Additionally, 22 patients had colon cancer, and eight patients had rectal cancer. Gas compounds were analyzed using gas chromatography and compared with those from healthy controls. Results: In the gas analysis, methyl mercaptan was significantly higher in the CRC group than in the control group. Hydrogen was significantly lower in the CRC group than in the control group and was correlated with tumor depth and advanced disease stage. Sensitivity, specificity, and accuracy of detection by a discriminant formula were 90%, 57.7%, arid 75%, respectively. Conclusion: Gas compounds from defecation constitute a promising, novel non-invasive approach for CRC screening.