RRM1 and metastatic malignant neoplasm in the lymph nodes: Multiple regression analysis for these seven variables showed that extrapancreatic invasion [P = 0.002; confidence interval (CI), 1.77–13.9], lymph node metastasis (P <0.001; CI, 1.87–6.42), non-adjuvant chemotherapy (P = 0.005; CI, 1.23–3.29), and high RRM1 (P = 0.017; CI, 1.12–3.23) were independent prognostic factors (Table 2).