Two studies apparently contradict this assumption, specifically regarding cystatin C. In colorectal cancer (Kos et al, 2000a) and lung cancer (Kos et al, unpublished results), the patients with high serum levels of cystatin C exhibited a significantly higher risk of death than those with lower levels of inhibitor, whereas a decreased metastatic spread was found in cystatin C deficient mice compared to wild-type mice (Huh et al, 1999). This evidence concerns the gene CST3 and lung cancer.