Purpose: Gallbladder and pancreas share common embryological origin, and malignancies of these organs may share common tumor antigens. CA 242 is a tumor marker for pancreatic cancer, but has not been studied in gallbladder cancer (GBC). We measured serum CA 242 levels in patients with GBC and compared it with those in patients with gallstones (GS) and healthy volunteers.
Methods: We enrolled consecutive patients with GBC (cases), GS (disease controls), and healthy volunteers (healthy controls). Serum CA 242, CEA, and CA 19-9 levels were measured using ELISA. Receiver operator curve was plotted for all the three markers.
Results: We studied 117 patients with GBC, 58 with GS, and 10 healthy volunteers. Among patients with GBC, 81 (69%) also had GB calculi. Patients with GBC more often had elevated CA 242 levels (64%) compared to those with GS (17%; p < 0.001) and healthy controls (0%; p < 0.001). The median levels of CA 242 was higher in the GBC group (59 [199] U/ml) compared to the GS group (10 [13] U/ml; p < 0.001) and the control group (3 [14.5] U/ml; p < 0.001). The sensitivity, specificity, positive predictive value (PPV), and negative predictive values of CA 242 for diagnosis of GBC were 64%, 83%, 88%, and 53%, respectively. At a cutoff of 45 U/ml, the specificity and PPV increased to 100%. CA 242 had higher AOC (0.759) compared to CEA (0.528) and CA 19-9 (0.430).
Conclusions: CA 242 is a promising tumor marker for GBC and performs better than CEA and CA 19-9.