We also found significant prognostic effects of elevated serum/plasma YKL-40 on OS among various cancer subgroups, such as gastrointestinal tumors, ovarian cancer, melanoma, lung cancer, urologic neoplasms and glioblastoma; in contrast, the prognostic effect of serum/plasma YKL-40 was not significant in breast cancer. This evidence concerns the gene CHI3L1 and lung cancer.