Abstract
BACKGROUND: Matrix metalloproteinase-8 (MMP-8) is a protease mainly expressed by neutrophils that cleaves numerous substrates, including collagens and cytokines. We have previously shown that serum MMP-8 levels increase in colorectal cancer (CRC) and correlate with distant metastasis. However, short follow-up in our prospective cohort did not enable survival analyses at the time of the first publication. METHODS: Preoperative serum MMP-8 levels were measured by immunofluorometric assay in 271 CRC patients and related to clinicopathological parameters, markers of systemic inflammation (modified Glasgow Prognostic Score, mGPS; serum levels of C-reactive protein (CRP), albumin and 13 cytokines), the density of six types of tumour-infiltrating immune cells and survival. RESULTS: Increased MMP-8 levels associated with higher mGPS and higher serum levels of CRP and several cytokines, including IL-1ra, IL-7 and IL-8 (p < 0.001 for all). Serum MMP-8 negatively correlated with tumour-infiltrating mast cells (invasive margin: p = 0.005, tumour centre: p = 0.010). The patients with high-serum MMP-8 levels (>100 ng/mL) had poor cancer-specific survival, independent of tumour stage, grade, lymphatic invasion, patient age, BRAF VE1 immunohistochemistry, mismatch repair deficiency, Immunoscore and mGPS (multivariate HR 2.12, 95% CI 1.21-3.71, p = 0.009). CONCLUSIONS: High-serum MMP-8 levels are associated with systemic inflammation and adverse outcome in CRC.