NOD2 and neoplasm: Univariate and multivariate analysis demonstrated that, apart from vascular invasion and tumor number, NOD2 expression remains as an independent prognostic factor of both OS (hazard ratio = 3.447, 95% CI: 1.931–6.154, P < 0.001) and TTR (hazard ratio = 3.010, 95% CI: 1.861–4.868, P < 0.001) (Additional file 1: Table S4).