RRM2 and cancer: High expression of RRM2 was significantly associated with clinical stage (IV vs. I: OR = 0.012, 95% confidence interval [CI] = 1.31–7.58, p = 0.012), T classification (T2 vs. T1: OR = 1.88, 95%CI = 1.28–2.79, p = 0.001), and cancer status (OR = 1.73, 95%CI = 1.12–2.71, p = 0.014).