Free Fatty Acid is a Promising Biomarker in Triage Screening for Patients with Colorectal Cancer: A Case-Control Study.

Purpose The aim of our study was to identify the diagnostic ability of free fatty acids (FFAs) in younger colorectal cancer (CRC) patients by comparing carcinoembryonic antigen (CEA) and carbohydrate antigen 19-9 (CA19-9). Methods Patients screened for CRC at Fujian Medical University Union Hospital from January 2011 to December 2014 were recruited. Patients pathologically diagnosed with CRC or colorectal adenoma (CA) and healthy control participants were included. The enzyme endpoint method was applied to measure FFA levels. Receiver operating characteristic (ROC) curve analysis was performed to further evaluate the diagnostic ability of FFAs. Results FFA levels in late-stage patients (tumour-node-metastasis (TNM) stages III-IV) were higher than those in early-stage patients (TNM stages I-II) (P=0.02). The FFA levels in CRC patients were higher than those in controls of all ages, those younger than 50 years, males and females (P<0.001), and this difference was larger for patients younger than 50 years and females than for the all ages group. There was no significant difference in the FFA level between CA patients and healthy participants (P=0.53). The area under the curve (AUC) values of FFA, CEA, CA19-9, FFA+CEA, FFA+CA19-9 and FFA+CEA+CA19-9 distinguished CRC patients from controls at all ages, with values of 0.604, 0.731, 0.640, 0.754, 0.678 and 0.758, respectively; however, in the younger CRC patients (age≤50), the AUC values were 0.701, 0.735, 0.669, 0.798, 0.749, and 0.801. The AUC in female patients younger than 50 years was larger than that in males (0.769 vs 0.660), and this value was greater than the value for CEA in males (0.739) and females (0.729). Conclusion The FFA level not only can complement the predictive ability of the CEA and CA19-9 levels but also has a superior predictive ability in female and younger patients with CRC. FFA levels may have a potential role in triage screening of early CRC.