What is the sensitivity and specificity of Carbohydrate Antigen 19-9 (CA 19-9) for pancreatic cancer?

From the Guidelines

CA 19-9 has a sensitivity of 79% to 81% and specificity of 80% to 90% for pancreatic cancer in symptomatic patients. This means that CA 19-9 can detect a significant proportion of pancreatic cancer cases, but it is not perfect and can miss some cases or produce false positives. The sensitivity and specificity of CA 19-9 are based on the best available evidence, including a study published in the Journal of the National Comprehensive Cancer Network 1.

Limitations of CA 19-9

The utility of CA 19-9 is limited by several factors, including:

• Elevated levels in other conditions such as benign pancreatic diseases, biliary obstruction, and other gastrointestinal cancers
• Approximately 5-10% of the population cannot produce CA 19-9 due to Lewis antigen negativity
• Early-stage pancreatic cancers often do not produce elevated levels of CA 19-9

Clinical Use of CA 19-9

CA 19-9 is most valuable when used in conjunction with other diagnostic methods, such as imaging studies, in patients with symptoms or risk factors for pancreatic cancer. It can also be used to monitor treatment response or recurrence in patients with known pancreatic cancer, as recommended by the NCCN Panel 1. Additionally, a study published in the Annals of Oncology found that CA 19-9 has a significant value as a prognostic factor and can be used to measure disease burden and guide treatment decisions 1.

Key Points

• CA 19-9 has moderate sensitivity and specificity for pancreatic cancer
• It is not suitable as a standalone screening test for the general population
• CA 19-9 is most useful in conjunction with other diagnostic methods and for monitoring treatment response or recurrence in patients with known pancreatic cancer.

From the Research

CA 19-9 Sensitivity and Specificity

• The sensitivity of CA 19-9 for pancreatic cancer has been reported to range from 70% to 85% in various studies 2, 3, 4.
• The specificity of CA 19-9 for pancreatic cancer has been reported to range from 87% to 95.9% in various studies 5, 3.
• A meta-analysis of 13 studies found that CA 19-9 had a higher sensitivity and diagnostic odds ratio compared to carcinoembryonic antigen (CEA) for pancreatic cancer, but no significant difference in specificity 6.
• The sensitivity and specificity of CA 19-9 can be affected by factors such as the cutoff value used, the population being studied, and the presence of jaundice or other conditions 5, 6.
• CA 19-9 has been found to be a useful marker for the diagnosis of pancreatic cancer, particularly when used in combination with other tests such as ultrasound or computed tomography (CT) 2, 5.

Factors Affecting CA 19-9 Sensitivity and Specificity

• The Lewis blood type has been found to affect the sensitivity of CA 19-9, with higher sensitivity in patients who are Lewis blood type positive 4.
• The presence of jaundice has been found to affect the sensitivity and specificity of CA 19-9, with higher sensitivity and specificity in patients with jaundice 5.
• The cutoff value used for CA 19-9 can affect the sensitivity and specificity, with higher cutoff values resulting in higher specificity but lower sensitivity 5, 6.

Clinical Applications of CA 19-9

• CA 19-9 can be used as a diagnostic marker for pancreatic cancer, particularly in combination with other tests such as ultrasound or CT 2, 5.
• CA 19-9 can be used to predict resectability and survival rate after surgery for pancreatic cancer 4.
• CA 19-9 can be used to monitor for recurrence of pancreatic cancer, with rising levels indicating potential recurrence 4.