Objective: Operative stress of cardiovascular surgery can alter the blood levels of various physiologically active substances (e.g., cytokines, growth factors), and thus potentially affect cancer cell proliferation. How the combination of changes in blood levels of these substances affects cancer cells has not been adequately addressed. We investigated the stimulatory capacity on cancer cells of serum from patients after cardiovascular surgery, using a novel in vitro assay method.
Methods: The subjects were 22 patients undergoing cardiovascular surgery, consisting of 11 off-pump and 11 on-pump procedures. Blood was sampled from each subject immediately before surgery, immediately after surgery, and after transfer to the intensive care unit. Human lung cancer cells were exposed to the serum of each blood sample from each patient, and an MTT assay was conducted to evaluate cell proliferation.
Results: Serum samples of all patients showed an inhibitory effect for lung cancer cell proliferation. This inhibitory effect was lower in postoperative serum compared with serum samples before surgery. As a result, lung cancer cell proliferation was better with postoperative serum samples than preoperative serum samples. The proliferation rate after surgery, when it was compared with preoperative serum, was significantly higher in patients with on-pump procedures than in patients with off-pump procedures.
Conclusion: The results of this study suggest that the operative stress of cardiovascular surgery induces changes in serum to make it less inhibitory for the cancer cell proliferation. This phenomenon is greater in patients with extracorporeal circulation.