The result had a low heterogeneity (P=0.16, I2 = 42%), so the fixed-effects model was adopted, and showed that the expression of OPN was positively correlated with lymph node metastasis of PCA (OR = 3.69, 95% CI [1.88, 7.23], P=0.0001) (Figure 4E). Here, SPP1 is linked to metastatic malignant neoplasm in the lymph nodes.