title: Comparative study of CEA and CA19-9 in esophageal, gastric and colon cancers individually and in combination (ROC curve analysis).
abstract: OBJECTIVE
  To determine the clinical serum levels of carcinoembryonic antigen (CEA) and carbohydrate antigen 19-9 (CA19-9), individually and in combination, for the diagnosis of 50 healthy subjects and 150 cases of esophageal, gastric, and colon cancers.
  
  
  METHODS
  The sensitivities of the two markers were compared individually and in combination, with specificity set at 100%. Receiver operating characteristic (ROC) curves were plotted.
  
  
  RESULTS
  Serum CEA levels were significantly higher in cancer patients than in the control group. The sensitivity of CEA was determined: in esophageal cancer, sensitivity=28%, negative predictive value (NPV)=61.72%, and AUC=0.742  (SE=0.05), with a significance level of P<0.0001; in gastric cancer, sensitivity=30%, NPV=58.82%, and AUC=0.734 (SE=0.05), with a significance level of P<0.0001; in colon cancer, sensitivity=74%, NPV=79.36%, and AUC=0.856  (SE=0.04), with a significance level of P<0.0001. The sensitivity of CA19-9 was also evaluated: in esophageal cancer, sensitivity=18%, NPV=54.94%, and AUC=0.573 (SE =0.05), with a significance level of P=0.2054. In gastric cancer, sensitivity=42%, NPV=63.29%, and AUC=0.679 (SE =0.05), with a significance level of P<0.0011. In colon cancer, sensitivity=26%, NPV=57.47%, and AUC=0.580 (SE =0.05), with a significance level of P=0.1670. The following were the sensitivities of CEA/CA19-9 combined: in esophageal cancer, sensitivity=42%, NPV=63.29%, SE=0.078 (95% CI: 0.0159-0.322); gastric cancer, sensitivity=58%, NPV=70.42%, SE=0.072 (95% CI: -0.0866-0.198); and colon cancer, sensitivity=72%, NPV=78.12%, SE=0.070 (95% CI: 0.137-0.415).
  
  
  CONCLUSIONS
  CEA exhibited the highest sensitivity for colon cancer, and CA19-9 exhibited the highest sensitivity for gastric cancer. Combined analysis indicated an increase in diagnostic sensitivity in esophageal and gastric cancer compared with that in colon cancer.
authors.affiliation: Department of Biochemistry, S.M.S. Medical College & Hospital, Jaipur 302004, India;
authors.forename: Bhawna
authors.initials: B
authors.lastname: Bagaria
authors.affiliation: Department of Biochemistry, S.M.S. Medical College & Hospital, Jaipur 302004, India;
authors.forename: Sadhna
authors.initials: S
authors.lastname: Sood
authors.affiliation: Department of Radiotherapy and Oncology, S.M.S. Medical College & Hospital, Jaipur 302004, India;
authors.forename: Rameshwaram
authors.initials: R
authors.lastname: Sharma
authors.affiliation: Advanced Bioinformatics Centre, Birla Institute of Scientific Research, Jaipur 302004, India.
authors.forename: Soniya
authors.initials: S
authors.lastname: Lalwani
keywords: Carcinoembryonic antigen; Receiver operating characteristic curve; carbohydrate antigen 19-9, human; sensitivity and specificity