LAUSR

Background Faecal calprotectin (FC) is a potential biomarker for colorectal cancer (CRC) screening. There is uncertainty if tumor characteristics are associated with FC levels. We investigated how tumor stage and tumor localization influence the extent of FC levels in patients with CRC in clinical practice. Methods In two cohorts of patients with CRC, we retrospectively analyzed FC tests (CALPRO®) performed within three months prior to diagnosis. One hundred twenty-four patients with CRC were included (mean age 68 years, 44% women). Results Ninety-eight patients with CRC (79%) had a FC ≥ 50 µg/g. FC correlated positively with tumor stage (UICC based on WHO TNM classification) (r s 0.24; p  = 0.007) and with CRP levels (r s 0.31, p  = 001), and a negatively with B-haemoglobin (r s -0.21; p  = 0.019). The patients with right-sided CRC had significantly more often a FC ≥ 50 µg/g than patients with left-sided CRC (92% vs 74% p = 0.027). In a binary logistic regression analysis, tumor stage III/IV (adjusted OR 3.47; CI 1.27–9.42) and right-sided tumor localization (adjusted OR 3.80; CI 1.01–14.3) were associated with FC ≥ 50 µg/g. Tumor stage III/IV (adjusted OR 2.30; CI 1.04–5.10) and acetylsalicylic use (adjusted OR 3.54; CI 1.03–12.2) were associated with FC ≥ 100 µg/g. In a cox regression analysis, a FC ≥ 100 µg/g was not associated with survival (Hazard OR 0.61; CI 0.24–1.52). Conclusions Elevated pre-diagnostic FC levels were common in patients with CRC in close proximity to diagnosis. Right-sided localization and tumor stage were significantly associated with a rise in FC levels.