CHI3L1 and breast cancer: Overall, as noted in Figure 2 and Table 2, the pooled analyses suggested that elevated YKL-40 expression was significantly associated with a poor prognosis regarding OS(HR=1.48, 95%CI= 1.11-1.97) and DFS(HR=1.51, 95%CI=1.10-2.07) in patients with breast cancer in the random -effect model, despite the presence of heterogeneity among the studies (OS: Ph=0.0001, I2=76%; DFS: Ph=0.003, I2=72%).