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Background: Colorectal cancer (CRC) is the third most commonly diagnosed malignancy globally. CRC patients with elevated plasma C-reactive protein (CRP) levels exhibit compromised prognoses. Toll-like receptors (TLRs), activating the innate and adaptive immune systems, may contribute to pro- and antitumorigenic inflammatory responses. We aimed to identify a possible link between local and systemic inflammatory responses in CRC patients by investigating the association between tissue TLRs and plasma CRP.

Methods: Tissue expressions of TLR2, TLR4, TLR5, and TLR7 were assessed using immunohistochemistry of tissue microarray slides from 549 CRC patients surgically treated between 1998 and 2005. Blood samples were drawn preoperatively, centrifuged, aliquoted, and stored at −80°C until analysis. Plasma CRP was determined through high-sensitivity time-resolved immunofluorometric assay. We investigated the association of TLRs to clinicopathologic variables, plasma CRP, and survival.

Results: High TLR2 expression (hazard ratio [HR] 0.59; 95% confidence interval [CI] 0.41–0.85; p = 0.005), high TLR5 expression (HR 0.60; 95% CI 0.45–0.83; p = 0.002), positive TLR7 expression (HR 0.49; 95% CI 0.33–0.72; p < 0.001), and low CRP (HR 1.48; 95% CI 1.08–2.11; p = 0.017) were associated with a better prognosis. A high TLR2 immunoexpression was associated with a better prognosis among low-CRP patients (HR 0.53; 95% CI 0.35–0.80; p = 0.002), high TLR4 expression among high-CRP patients (HR 2.04; 95% CI 1.04–4.00; p = 0.038), high TLR5 expression among low-CRP patients (HR 0.059; 95% CI 0.37–0.92; p = 0.021), and positive TLR7 expression among low-CRP patients (HR 0.53; 95% CI 0.28–1.00; p = 0.049). In multivariate analyses, no biomarkers emerged as significant independent variables.

Conclusions: High tissue TLR2, TLR5, and TLR7 levels were associated with a better prognosis. Among low-CRP patients, those with high TLR2, TLR5, and TLR7 immunoexpressions exhibited a better prognosis. Among high CRP patients, a high TLR4 immunoexpression was associated with a better prognosis.