Second, a meta-analysis with 8 included studies was performed to investigate the prognostic value of YKL-40 in glioblastoma by Qin et al. [10], and another meta-analysis with 10 included studies was performed to investigate the prognostic value of YKL-40 in breast cancer by Wan et al. [11] Both found that elevated YKL-40 was associated with poor prognosis. This evidence concerns the gene CHI3L1 and breast cancer.