Activation capacity of the alternative and classic complement pathways in patients operated on for colorectal cancer

Tumor cells may suppress activation of the host's complement system, and the functional state of the complement system may be a prognostic marker of outcome in patients with malignancies. Serial plasma samples from patients undergoing intended curative surgery for colorectal cancer were analyzed for complement factor C3 activation capacity.

Samples were collected from 91 patients with colorectal cancer and 13 with benign colorectal diseases before surgery and 1, 2, and 7 days after surgery, between 8 and 13 days after surgery, and 3, 6, 12, 18, 24, 36, 48, and 60 months after surgery. The samples were analyzed with an enzyme-linked immunosorbent assay that measured C3 activation capacity by the alternative and classic complement pathways. Cancer patients were compared according to Dukes stage, type of surgery performed, transfusion of blood, development of infection, venous thromboembolism, and cancer recurrence.

Plasma samples obtained from cancer patients before surgery showed C3 activation capacities corresponding to those of samples from patients with benign disease. For both patient groups, C3 activation capacity decreased after surgery and normalized within seven days. Significant differences in C3 activation capacities were observed between cancer patients that were related to Dukes stage and in patients with and without buffy coat-depleted red cells suspended in saline, adenine, glucose, and mannitol transfusion, infectious events, and deep venous thromboembolism. Measurement of C3 activation capacity was of predictive value in patients who developed infection.

Serial measurements of C3 activation capacity in plasma from patients who had undergone surgery for colorectal cancer revealed significant differences related to Dukes staging after surgery and to the development of infections but not to cancer recurrence.