Background: Colorectal cancer is the third most common cancer-related mortality worldwide, and its prevalence is increasing among many nations. Aim of the study: Investigate the predictive value of carbohydrate antigen 242 (CA242) in comparison to the CEA biomarker and to estimate the significance of CA242 as prognosis maker in colorectal cancer patients. Methods: a case-control study with a total of 150 individuals, 100 patients (59 males, 41 females) and 50 healthy controls (26 males, 24 females). using an enzyme-linked immunosorbent (ELISA) to determine the serum levels of CA242 and CEA. The study was carried out at the gastroenterology consultation clinic of the oncology teaching hospital between November 2020 and February 2021in Baghdad, Iraq. Result: Patients with colorectal cancer had significantly higher CA242 levels than healthy controls (p >0.001) with a significant positive correlation between CA242 and CEA (r = 0.866, p >0.001). The CA242 ROC curve study revealed an AUC of 0.933, a sensitivity of 89%, a specificity of 88%, and a cutoff value of 45 U/ml. CA242 can serve as a potential prognostic biomarker for colorectal cancer.
