PLK1 and neoplasm: No significant relationships were observed between PLK1 expression and age (OR=1.19, 95% CI: 0.77-1.84, P=0.437, random effect model), gender (OR=0.87, 95% CI: 0.71-1.07, P=0.191, fixed effect model), histology grade (OR=1.07, 95% CI: 0.66-1.73, P=0.783, random effect model), depth of tumor invasion (OR=1.70, 95% CI: 0.97-2.98, P=0.061, random effect model), or metastasis (OR=1.37, 95% CI: 0.79-2.37, P=0.209, fixed effect model).