From the Guidelines
The most commonly used marker for pancreatic cancer is CA 19-9 (carbohydrate antigen 19-9), which measures levels of a protein that may be elevated in pancreatic cancer patients, with values above 37 U/mL generally considered abnormal. However, CA 19-9 is not perfect for diagnosis as it can be elevated in other conditions like pancreatitis, liver disease, and other gastrointestinal cancers 1. Additionally, about 10% of the population cannot produce CA 19-9 due to genetic factors, which reduces its value as a screening biomarker 1. Other markers sometimes used include CEA (carcinoembryonic antigen), CA-125, and CA 72-4, though these are less specific.
For monitoring treatment response in diagnosed patients, regular CA 19-9 testing every 1-3 months is often recommended 1. It's essential to understand that tumor markers alone cannot diagnose pancreatic cancer; they must be used alongside imaging studies (CT, MRI, endoscopic ultrasound) and potentially biopsy for definitive diagnosis. The value of these markers lies in their ability to help monitor disease progression and treatment response rather than as standalone diagnostic tools.
Some key points to consider when using CA 19-9 include:
- CA 19-9 is not useful for the primary diagnosis of pancreatic cancer, but it has a significant value as a prognostic factor and can be used to measure disease burden and guide treatment decisions 1.
- A preoperative serum CA 19-9 level ≥500 UI/ml clearly indicates a worse prognosis after surgery 1.
- CA 19-9 levels should be interpreted with caution, as they can be elevated in other conditions and may not be detectable in individuals with certain genetic factors 1.
- Combining CA 19-9 with other markers or imaging studies may improve diagnostic accuracy, but more research is needed to determine the optimal approach 1.
In summary, while CA 19-9 is a commonly used marker for pancreatic cancer, it has limitations and should be used in conjunction with other diagnostic tools to ensure accurate diagnosis and monitoring of the disease. Regular CA 19-9 testing, combined with imaging studies and potentially biopsy, is recommended for monitoring treatment response in diagnosed patients.
From the Research
Pancerat Cancer Marker
- CA 19-9 is the most commonly used and best validated serum tumor marker for pancreatic cancer diagnosis in symptomatic patients and for monitoring therapy in patients with pancreatic adenocarcinoma 2.
- The sensitivity of CA 19-9 is approximately 80%, with a specificity of 82-90% for the diagnosis of pancreatic cancer in symptomatic patients 3, 4, 5.
- CA 19-9 has several limitations, including poor sensitivity, false negative results in Lewis negative phenotype, and increased false positivity in the presence of obstructive jaundice 2, 4, 5.
- Pre-operative CA 19-9 serum levels can provide useful prognostic information, with patients with normal levels having a prolonged median survival compared to patients with elevated levels 4, 5.
- CA 19-9 serum levels can also predict post-operative recurrence and response to chemotherapy, with normalization or a decrease in post-operative CA 19-9 serum levels associated with prolonged survival 4, 5.
Clinical Utility of CA 19-9
- CA 19-9 is not useful as a screening marker for asymptomatic populations due to its low positive predictive value 2, 4, 5.
- CA 19-9 has a role in the diagnosis, prognosis, and management of pancreatic adenocarcinoma, with its serum levels providing important information on prognosis, overall survival, and response to chemotherapy 3, 4, 5.
- Lewis antigen status should be determined when using CA 19-9 as a biomarker, as false negatives can occur in Lewis-negative individuals 6.
- CA 19-9 has potential as a therapeutic target for cancer, with strategies including therapeutic antibodies and vaccines, CA 19-9-guided nanoparticles, and inhibition of CA 19-9 biosynthesis 6.