Efficiency of serum cytokeratin 18 levels for monitoring of colorectal cancer patients under chemotherapy

In this study we investigated the efficiency of serum cytokeratin 18 M30 and M65 protein levels for monitoring of colorectal cancer patients under Folfox chemotherapy. Usefulness of cytokeratin 18 to monitor the response to chemotherapy treatment has been compared with carcinoembryonic antigen and radiological tumor size.Serum cytokeratin 18 levels were measured with M65-ELISA and M30-ELISA methods which are spesific for total cell death and apoptotic cell death respectively. Carcinoembryonic antigen level was measured by chemiluminescence immunometric assay. Clinical responses to treatments were evaluated according to the Response Evaluation Criteria in Solid Tumors (RECIST).Cytokeratin 18 levels showed an increasing or decreasing pattern during chemotherapy treatment of the patients. It has been determined that dominant cell death type was necrosis at the day total cell death was maximum. Individual differences in M30/M65 ratio of patients and healthy subjects have been determined. Although patients who were considered as partial response according to the Response Evaluation Criteria in Solid Tumors showed an increase of serum M30 levels at the third chemotherapy cure, patients who were decided as progressive disease did not show an increase of M30 levels. We conclude that M30 is more effective than carcinoembryonic antigen for monitoring of colorectal cancer patients under neoadjvant chemotherapy. Increase in serum M30 and M65 levels of the patients who did not show progression may be considered as a side effect of chemotherapy.As a result the present study did not include sufficient number of patients to warrant any statement with regard to the clinical utility of cytokeratin 18 serum measurements, so larger studies should be accomplished.Key Words: Cytokeratin 18, M30, M65, colorectal cancer, chemotherapy, carcinoembryonic antigen, apoptosis, necrosis.