Evaluation of serum midkine and carcinoembryonic antigen as diagnostic biomarkers for rectal cancer and synchronous metastasis

METHODS: S-MK and CEA, related to cancer status, were measured in 106 patients and 30 controls by ELISAs. Diagnostic and Prognostic values of S-MK and CEA for rectal cancer were conducted by receiver operating characteristic (ROC) curves with the analysis of sensitivity, specificity, diagnostic accuracy, positive predictive value (PPV) and negative predictive value (NPV) for differential diagnosis. RESULTS: Pre-surgical S-MK was elevated in cancer patients than the normal and benign subjects. In term of phases, S-MK and CEA of T3/T4 were both significantly higher than those in T1/T2, with further up-regulation of S-MK. The diagnostic capability of S-MK was higher than CEA and increased in integrating S-MK with CEA when differentiated rectal cancer, benign rectal polyps and normal subjects. Moreover, when evaluating metastasis predictive efficacies, the combination of S-MK and CEA showed higher accuracy than any individual parameter. CONCLUSIONS: Pre-surgical S-MK is a rectal cancer indicator which is superior to CEA. It can potentially be used to monitor the prognosis of rectal cancer, and predict synchronous metastases, providing assistance to clinicians.