From the Guidelines
Elevated Carbohydrate Antigen 19-9 (CA19-9) levels are a significant indicator of pancreatic cancer and should prompt further investigation, including imaging studies and possibly endoscopic ultrasound, as they are not specific enough for diagnosis on their own. The clinical significance of elevated CA19-9 levels is supported by the European Society for Medical Oncology (ESMO) clinical practice guidelines for diagnosis, treatment, and follow-up of pancreatic cancer 1. According to these guidelines, CA 19-9 is the most useful tumor marker in pancreatic cancer, with an increase in serum levels seen in almost 80% of patients with advanced disease 1.
Key Points to Consider
- CA19-9 levels can be elevated in non-cancerous conditions, including pancreatitis, liver disease, and biliary obstruction, so elevation needs to be interpreted in clinical context 1.
- About 5-10% of the population cannot produce CA19-9 even with cancer present, while levels above 1000 U/mL are more concerning for malignancy 1.
- Serial measurements over time are often more valuable than a single reading, and the normal range is typically below 37 U/mL, though this varies by laboratory.
- If cancer is suspected, additional tests, including comprehensive blood work, other tumor markers, and possibly tissue biopsy, may be ordered for definitive diagnosis 1.
Diagnostic Approach
The diagnostic approach for elevated CA19-9 levels should include imaging studies, such as CT scan or MRI of the abdomen, to determine the tumor size and precise burden, as well as arterial and venous local involvement 1. Endoscopic ultrasound (EUS) may also be valuable in the detection of vascular invasion and prediction of resectability, with a sensitivity of 85% and specificity of 91% 1.
Prognostic Value
A preoperative serum CA 19-9 level ≥500 UI/ml clearly indicates a worse prognosis after surgery 1. The level of CA 19-9 is correlated to the level of bilirubin, and any cause of cholestasis can induce false-positive results 1. Therefore, it is essential to interpret CA19-9 levels in the context of clinical presentation and other diagnostic findings.
From the Research
Significance of Elevated Carbohydrate Antigen 19-9 (CA19-9)
Elevated CA19-9 levels can be associated with both malignant and benign diseases. The significance of elevated CA19-9 levels includes:
- Elevated CA19-9 levels are often used as a tumor marker for pancreatic, gastric, and hepatobiliary malignancies 2
- High CA19-9 levels can indicate unresectable lesions and a poor prognosis 2
- CA19-9 levels can be elevated in benign conditions such as disease of the hepatobiliary system, pneumonia, pleural effusion, renal failure, and systemic lupus erythematosus (SLE) 2
- Extreme elevation of CA19-9 levels is rare in benign diseases, but can occur in cases such as xanthogranulomatous cholecystitis 3
Causes of Elevated CA19-9 Levels
The causes of elevated CA19-9 levels can be varied and include:
- Malignant diseases such as pancreatic, colorectal, lung, liver, and ovarian cancer 2
- Benign diseases such as hepatic diseases, pulmonary diseases, gynecologic diseases, endocrine diseases, and spleen disease 4
- Unknown causes, which can account for up to 23.4% of cases 4
Diagnostic Approach
When evaluating elevated CA19-9 levels, it is essential to:
- Interpret the results in the context of the patient's clinical presentation 2
- Be aware of the benign conditions that can cause elevated CA19-9 levels 2
- Use a systematic approach to investigate the causes of elevated CA19-9 levels, including imaging studies and laboratory tests 4
- Consider alternative diagnoses, such as xanthogranulomatous cholecystitis, in cases of extremely elevated CA19-9 levels 3
Clinical Implications
Elevated CA19-9 levels can have significant clinical implications, including: