PKM and metastatic malignant neoplasm in the lymph nodes: Pooled data indicated that high PKM2 expression is related to lymph node metastasis (N1+N2+N3 vs N0, OR = 1.97, 95%CI = 1.39–2.80, P = .0001) (Fig. 5), minor heterogeneity was found among the 4 studies (I2 = 35%, P = .20), therefore, a fixed effect model was adopted.