This study evaluates a new serum-based biomarker for colorectal cancer (CRC) screening and diagnosis. The biomarker (GTA-446) is a member of hydroxy -polyunsaturated ultra-long chain fatty acids and was found to be reduced in CRC patients compared to CRC-free subjects. Diagnostic test performance characteristics were used to identify the effectiveness of the test. Methods: Serum levels of GTA-446 were measured in 4924 subjects who underwent colonoscopy for any reason, pathology results and clinical data were also collected. Two sets of age-matched control subjects were used; First were the lab controls (number=383) which were serum samples collected from Saskatchewan Disease Control Laboratory along with age and gender data. Second, were the endoscopy controls (number=762) which were obtained from the colonoscopy population after being determined to be cancer-free. Cut-off values were calculated using Receiver Operating Characteristic (ROC) curve. Results: Serum GTA-446 was found to be reduced in 87% of CRC patients. Compared to lab controls, the GTA-446 biomarker has a sensitivity of 87%, specificity of 75%, positive likelihood ratio of 3.6, and negative likelihood ratio of 0.16. Using endoscopy controls to calculate test performance characteristics, the biomarker has a sensitivity of 87%, specificity of 50%, positive likelihood ratio of 1.74, and negative likelihood ratio of 0.24. Also, the level of GTA-446 was found to significantly decline with age (r=-0.20, p<0.01). Conclusion: Serum GTA-446 is a potential biomarker for minimally invasive detection of colorectal cancer that compares favorably to other serum-based biomarkers.

Based on a thesis in Electrical Engineering, 1965. / Bibliography: p.79-86. / Contract DA-36-039-AMC-03200(E).

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