From the Guidelines
Tumor markers differ significantly between gastric and pancreatic carcinomas, with CA 19-9 being the most valuable marker for pancreatic cancer, as it is elevated in 70-90% of cases, whereas CA 72-4 has greater specificity for gastric cancer. The primary tumor markers for gastric carcinoma include CEA (carcinoembryonic antigen), CA 72-4, CA 19-9, and pepsinogen, with CEA being elevated in 40-50% of gastric cancer cases 1. In contrast, pancreatic carcinoma primarily relies on CA 19-9, which tends to be significantly more elevated in pancreatic cancer than in gastric cancer, often exceeding 1000 U/mL in pancreatic malignancies 1. Other useful markers for pancreatic cancer include CEA and CA 125. However, no single tumor marker is completely specific for either cancer type, so clinical correlation with imaging studies and histopathological confirmation remains essential for definitive diagnosis, as stated in the ASCO 2006 update of recommendations for the use of tumor markers in gastrointestinal cancer 1. These markers are most valuable for monitoring treatment response and detecting recurrence rather than for initial diagnosis. It is also important to note that around 10% of individuals are negative for Lewis antigen a or b (a-b-) and do not have detectable CA19-9, reducing its value as a screening biomarker, as mentioned in the evaluating susceptibility to pancreatic cancer: ASCO provisional clinical opinion 1. Additionally, CA-19-9 may also be elevated in patients with nonmalignant diseases, including liver cirrhosis, chronic pancreatitis, cholangitis, and other GI cancers, highlighting the need for careful interpretation of tumor marker results in the context of clinical presentation and other diagnostic findings. The use of multimarker panels and circulating tumor DNA is an area of active investigation, with the goal of improving biomarker diagnostic performance for pancreatic cancer, as discussed in the evaluating susceptibility to pancreatic cancer: ASCO provisional clinical opinion 1. In clinical practice, the most recent and highest quality study, such as the evaluating susceptibility to pancreatic cancer: ASCO provisional clinical opinion 1, should be prioritized when making decisions about tumor marker use in gastric and pancreatic carcinomas.
From the Research
Tumor Markers in Gastric Carcinoma vs Pancreatic Carcinoma
- The most commonly used biomarkers for diagnosis and management of patients with pancreatic cancer are CA 19-9 and CEA 2.
- In gastric carcinoma, the sensitivity of CEA was 48.6%, of CA 19-9 was 64.9%, and of CA-50 was 70.3% 3.
- CA 19-9 is the most studied cancer marker and moderately accurate in patients suspected of having pancreatic cancer 4.
- The estimation of CA 19-9 and CA-50 may be useful for early detection of recurrence after curative surgery and adjuvant chemotherapy in gastric cancer 3.
- In patients with pancreatic carcinoma, the CEA levels both in sera and peritoneal cavity were parallel but peritoneal levels were slightly higher in stages III and IV, and Ca 19-9 was more sensitive for pancreatic cancer 5.
Comparison of Tumor Markers
- The combined sensitivity of CA 19-9 in pancreatic carcinoma was 78.2% and the specificity was 82.8% 2.
- In gastric carcinoma, the comeasurement of CA 19-9 and CA-50, and to some degree of CEA, is justifiable for diagnosis, monitoring, and prognosis 3.
- The levels of tumor markers in sera could signalize inoperability of tumor, and peritoneal levels could predict R1 resection especially in gastric cancer patients and risk of early peritoneal recurrence of the disease 5.
Clinical Utility
- The serum tumor marker cancer antigen 19-9 can be used to confirm the diagnosis and to predict prognosis and recurrence after resection in pancreatic cancer 6.
- In advanced or recurrent gastric cancer, the estimation of either CA 19-9 or CA-50 and CEA serum values may help in checking the prognosis, determining the efficacy of palliative treatment modalities, and recognizing recurrences 3.
- Initial serologic testing should include transaminase and bilirubin levels, and in patients with midepigastric pain, lipase levels, and Carbohydrate antigen 19-9 is the most studied cancer marker and moderately accurate in patients suspected of having cancer 4.