The results of pooled analysis demonstrated that there was no significant association between TIMP-2 expression and tumor grade (n = 7, OR = 1.02, 95 % CI = 0.68–1.54) (Fig. 4a), but there was significant heterogeneity (I2 = 71.4 %, P = 0.002), so we performed the analysis through a random-effect model. Here, TIMP2 is linked to neoplasm.