Cancer Antigen (CA) 242

The Cancer Antigen (CA) 242 blood test, also known as Carbohydrate Antigen 242, is used to monitor therapeutic response and to detect recurrence in pancreatic, colon, and rectal cancers. In the assessment of suspected gastrointestinal malignancy, CA 242 provides adjunctive information to help distinguish cancer from benign conditions such as pancreatitis and hepatic disease; results are interpreted in conjunction with clinical evaluation and other diagnostic tests.

CA 242 is a high–molecular‑weight glycoprotein originating from gastrointestinal epithelial cells. It is related to, yet analytically distinct from, CA 19‑9; in some studies, CA 242 demonstrates higher sensitivity and specificity for gastrointestinal malignancies. Serum concentrations are commonly increased in tumors of the gastrointestinal tract, with the most consistent elevations observed in pancreatic and colorectal carcinomas. Tumor release of CA 242 into the circulation enables its use as a serum tumor marker for early assessment of disease activity and for longitudinal follow‑up. Benign gastrointestinal disorders generally show lower CA 242 expression than malignant disease, supporting its role in differential diagnosis when used with other clinical data. In colorectal cancer, a rising CA 242 can precede clinically evident recurrence by approximately 5–6 months.