Background: Colorectal cancer (CRC) is the third most common cancer worldwide motivating national screening strategies utilizing fecal immunochemical tests (FIT). Blood-based biomarkers could be an alternative method to increase compliance in population-based screening programs for early detection of CRC. We aimed to identify new blood-based biomarkers that could be potential candidates for use in colorectal cancer screening. Methods: In a nested cohort study of 1967 FIT positive participants of the Danish CRC screening program serum levels of GDF-15, hepsin, IL-8, keratin1-10, L1CAM, MIA, monocyte MCP-1, NSE and OPG were measured using the Luminex xMAP immunoassay platform. Main outcomes were CRC vs non-CRC and CRC, high-risk adenomas (HRA) or medium-risk adenomas (MRA) vs low-risk adenomas (LRA) or clean colorectum. Odds ratios for associations between biomarker expressions and outcomes were calculated using logistic regression models and visualized by area under the receiver operating characteristic (ROC) curve (AUC). Analyses were made on the Luminex biomarkers alone and with addition of clinical and demographic information. Results: FIT-induced colonoscopies detected 240 CRCs and 625 HRA or MRA. Multivariate analyses using all biomarkers and age found hepsin, IL-8 and OPG significantly (p<0.001) associated in relation to the main outcome (CRC vs non-CRC) with odds ratios of 0.74 [0.59-0.92], 2.59 [2.12-3.15] and 0.90 [0.82-0.99], respectively. The full model using all biomarkers and age presented an AUC of 0.73 [0.70-0.77]. Conclusions: Changed serum levels of nine novel biomarkers seem to be potential predictors for early detection of CRC, especially hepsin, IL-8 and OPG.

OR: Odds ratio; CRC: colorectal cancer; HRA: high-risk adenoma; MRA: medium-risk adenoma; LRA: low-risk adenoma; CI: confidence interval; AUC: area under the ROC curve. * AUC after 10-fold cross validation repeated 10 times.