Aim: A raised systemic inflammatory response correlates with poorer colorectal cancer (CRC) outcomes. Faecal immunochemical test bowel screening aims to detect early-stage disease. We assessed the relationship between systemic inflammatory response, screen detection and CRC survival.Method: A retrospective, observational cohort study compared screen-detected and non-screen-detected CRC patients undergoing resection. Systemic inflammatory response was measured using lymphocyte/monocyte, neutrophil/lymphocyte and platelet/lymphocyte ratios (LMR, NLR, PLR). Covariables were compared using chi 2 testing and survival with Cox regression.Results: A total of 761 patients were included (326 screen-detected, 435 non-screen-detected). Screen-detected patients had lower systemic inflammatory response: low (<2.4) LMR (28.8% vs. 44.6%; P < 0.001), moderate (3-5) or high (>5) NLR (26.1% vs. 30.6%, P < 0.001; and 7.7% vs. 19.5%, P < 0.001) and high (>150) PLR (47.2% vs. 64.6%; P < 0.001). Median follow-up was 63 months. On univariate analysis, non-screen detection (hazard ratio [HR] 2.346, 95% CI 1.687-3.261; P < 0.001), advanced TNM (P < 0.001), low LMR (HR 2.038, 95% CI 1.514-2.742; P < 0.001), moderate NLR (HR 1.588, 95% CI 1.128-2.235; P = 0.008), high NLR (HR 2.382, 95% CI 1.626-3.491; P < 0.001) and high PLR (HR 1.827, 95% CI 1.326-2.519; P < 0.001) predicted poorer overall survival (OS). Non-screen detection (HR 2.713, 95% CI 1.742-4.226; P < 0.001), TNM (P < 0.001), low LMR (HR 1.969, 95% CI 1.340-2.893; P < 0.001), high NLR (HR 2.368, 95% CI 1.448-3.875; P < 0.001) and high PLR (HR 2.110, 95% CI 1.374-3.240; P < 0.001) predicted poorer cancer-specific survival (CSS). On multivariate analysis, non-screen detection (HR 1.698, 95% CI 1.152-2.503; P = 0.008) and low LMR (HR 1.610, 95% CI 1.158-2.238; P = 0.005) independently predicted poorer OS. Non-screen detection (HR 1.847, 95% CI 1.144-2.983; P = 0.012) and high PLR (HR 1.578, 95% CI 1.018-2.444; P = 0.041) predicted poorer CSS.Conclusion: Screen-detected CRC patients have a lower systemic inflammatory response. Non-screen detection and systemic inflammatory response (measured by LMR and PLR respectively) were independent predictors of poorer OS and CSS.