We currently found that approximately a half (21.1%) of YKL-40-positive cancers (40.4%) expressed strong YKL-40, the population of which may account for the evidence reported previously that 20–24% of patients demonstrate elevated serum levels of YKL-40 in overall breast cancer population (Johansen et al, 1995, 2003). The gene discussed is CHI3L1; the disease is cancer.