Comparison between serum levels of carcinoembryonic antigen, sialic acid and phosphohexose isomerase in lung cancer.

The identification and application of quantifiable tumor markers as adjuncts to clinical care is a story of both success and failure. The present study compared serum levels of carcinoembryonic antigen (CEA) with total sialic acid/total protein (TSA/TP) ratio and phosphohexose isomerase (PHI) in 192 untreated lung cancer patients as well as 80 age and sex matched controls (44 non-smokers and 36 smokers). CEA values were significantly raised (p < 0.001) in smokers as compared to the non-smokers; whereas, TSA/TP and PHI values were comparable between the two groups of the controls. All the biomarkers were significantly elevated (p < 0.001) in untreated lung cancer patients as compared to the controls. Receiver operating characteristic curve analysis revealed higher sensitivities of TSA/TP and PHI as compared to CEA at different specificity levels between 60% and 95%. Mean values of CEA, TSA/TP and PHI were higher in non-responders compared to the responders. The results indicate that TSA/TP and PHI are superior tumor markers than CEA for lung cancer patients.