However, we determined that higher MMP-9 levels correlate with advanced tumor stage (OR = 5.17, 95% CI 2.85–9.38, P < 0.00001, RE model; OR = 5.22, 95% CI 2.88–9.48, P < 0.00001, QE model) (Additional file 3: Figure S3), independent of gender (OR = 0.60, 95% CI 0.26–1.34, P = 0.21, RE model; OR = 0.60, 95% CI 0.27–1.36, P = 0.12, QE model) (Additional file 3: Figure S3). Here, MMP9 is linked to neoplasm.