Abstract
BACKGROUND: Colorectal cancer (CRC) is one of the leading causes of cancer-related mortality worldwide. Delays in diagnosis remain common, and there is ongoing interest in whether routinely available laboratory parameters may provide early signals of increased risk. Systemic inflammatory markers derived from complete blood count, such as the neutrophil–lymphocyte ratio (NLR), monocyte–lymphocyte ratio (MLR), platelet–lymphocyte ratio (PLR), and systemic immune-inflammation index (SII), have been proposed as potential adjunctive biomarkers; however, their diagnostic value in real-world colonoscopy populations remains uncertain. AIM: To explore the discriminatory performance of NLR, MLR, PLR, and SII for identifying malignant findings among patients undergoing colonoscopy. METHODS: This retrospective single-center study included adults who underwent colonoscopy and had a complete blood count performed prior to the procedure between 2014 and 2024. Participants were classified as having benign, premalignant, or malignant findings based on colonoscopy and histopathology reports. Inflammatory indices were calculated and compared across groups. Receiver operating characteristic (ROC) analyses were performed to assess discriminatory performance. Multivariable logistic regression analyses adjusted for age, sex, and hemoglobin were conducted to evaluate independent associations. RESULTS: Among the included patients, 53 (18.8%) had malignant and 77 (27.3%) had premalignant findings. Median values of NLR, MLR, PLR, and SII were significantly higher in patients with malignant findings compared with non-malignant groups (p < 0.05). However, discriminatory performance was limited, with AUC values ranging from 0.63 to 0.69. In multivariable analyses, inflammation-based indices showed at most modest independent associations with malignancy after adjustment for age, sex, and hemoglobin. CONCLUSIONS: Inflammation-based indices derived from routine complete blood count testing demonstrated statistically significant but limited ability to distinguish malignant from non-malignant colonoscopy findings. Given their modest discriminatory performance and limited independent associations, these markers should be regarded as exploratory and hypothesis-generating rather than clinically actionable diagnostic tools. Further prospective, multicenter studies are required to clarify their potential role, if any, in CRC risk assessment.