Changes in serum cathepsin B-like activity in patients with colorectal cancer

Cathepsin B-like activity (CB-like) was estimated in sera of 30 male patients with colorectal cancer (n = 20), benign polyps of the rectum (n = 10) and in sera of control subjects (n = 50). Both total and residual activities of the enzyme in colorectal cancer patients showed a significant elevation in comparison with control subjects and patients with benign polyps. In the course of antitumor therapy a decline in catheptic activity was observed when a reduction in the volume of tumor tissue was present. On the other hand, an increment in CB-like activity was observed when antitumor therapy had no effects or tumor relapse was present.