These increased levels have also been observed to be associated with poorer survival of cancer patients (Cintin et al, 1999, 2002; Hogdall et al, 2003; Jensen et al, 2003; Johansen et al, 2003; Bergmann et al, 2005; Pelloski et al, 2005), suggesting that serum levels of YKL-40 are a prognostic cancer biomarker. This evidence concerns the gene CHI3L1 and cancer.