We also found significant prognostic effects of elevated serum/plasma YKL-40 on OS in various cancer subgroups such as gastrointestinal tumors, ovarian cancer, melanoma, lung cancer, urologic neoplasms and glioblastoma, whereas the prognostic effect of serum/plasma YKL-40 was not statistically significant in breast cancer. The gene discussed is CHI3L1; the disease is breast cancer.