Definition

The CA 19-9 test measures the concentration of CA 19-9 protein, also known as cancer antigen 19-9, within a blood sample. This protein is synthesized by various cells in the body, including certain healthy cells and specific cancer cells.

CA 19-9 serves as a tumor marker, a category encompassing substances detected in tissues, blood, or other bodily fluids. It may indicate the presence of cancer or in certain cases, nonmalignant conditions. 

While small amounts of CA 19-9 can be found in the bloodstream of healthy individuals, elevated levels could signify the presence of pancreatic cancer. However, increased CA 19-9 levels can also signal other cancer types or noncancerous diseases. Notably, infections affecting the liver, gallbladder, and pancreas, such as gallstones and liver cirrhosis, can play a role in increased CA 19-9 levels.

Given the varied implications of elevated CA 19-9 levels, the test is not utilized alone for cancer screening or diagnosis. Instead, the test is usually employed alongside other diagnostic modalities, such as medical imaging, to facilitate in monitoring recurrence of disease or response of treatment in patients.

We also have an article on pancreatic cancer which you can read here: Pancreatic Cancer - Definition, Cause and Risk Factor.

Indication

There are various indications on why a CA 19-9 test may be conducted, which include:

Diagnosis of Cancer and Other Medical Conditions

Elevated CA 19-9 levels can indicate the presence of pancreatic cancer and certain digestive system cancers. Non-cancerous conditions such as cirrhosis (liver scarring) can also lead to increased CA 19-9 levels. However, due to the potential influence of many conditions to this tumor marker, this test is not solely relied upon for cancer diagnosis. Typically, the result of this test is integrated with the outcomes of other diagnostic tests, including medical imaging and biopsies, to ascertain the presence of cancer or other medical conditions.

Assessing Cancer Treatment Efficacy

Following a cancer diagnosis, routine CA 19-9 test could aid physicians in gauging the response of cancer in patients to the given therapy. In the context of pancreatic cancer patients, for instance, a baseline CA 19-9 level is typically established post-diagnosis. Subsequent measurements obtained during or after treatment serve as comparative benchmarks against the baseline level. Such periodic evaluations facilitate clinicians in determining the effectiveness of therapeutic regimens and in devising tailored treatment strategies.

Estimating Cancer Prognosis

The degree of CA 19-9 elevation, both upon initial diagnosis and following treatment, represents one of several factors that could inform physicians in assessing a patient's prognosis. The process of delineating the probable disease outcome is influenced by factors such as the stage of cancer, concurrent medical conditions, and the overall health status of the patient. By integrating CA 19-9 levels with these clinical parameters, physicians can better forecast disease progression and tailor therapeutic strategies accordingly.

Monitoring for Cancer Recurrence

In pancreatic cancer patients who have undergone surgical intervention, CA 19-9 testing may be used to look for the signs of disease reappearance in the future. By periodically measuring CA 19-9 levels post-treatment, clinicians can scrutinize for indications of cancer recurrence, facilitating timely intervention and management.

Contraindication

There are no individuals for whom it is advised against to check their serum CA 19-9 level; everyone is eligible to undergo blood tests for monitoring the levels of CA 19-9 in their bodies.

Preparations Prior to Test

No test preparation is needed prior to the CA 19-9 test. Ensure your healthcare provider is aware of any medications or supplements you may be taking. Whether or not you need to stop taking any of these medications for the test depends on your physician's instructions.

Test Procedures

A healthcare professional will extract a blood sample from a vein, usually in your arm, using a tiny needle. Once the needle is placed, a little sample of blood will be drawn into a test tube. You may experience a slight stinging sensation when the needle is inserted or removed.

Normal and Abnormal Values

The levels of CA 19-9 are measured in U/mL or units per milliliter, and the reports could also provide interpretations of these measurements, indicating whether they fall within normal or abnormal ranges. 

Normal CA 19-9 levels typically fall between 0-37 U/mL. Elevated levels are commonly associated with pancreatic cancer; however, high levels can also manifest in healthy individuals with no underlying pathology. It is crucial to recognize that elevated CA 19-9 levels do not definitively signify the presence of cancer.

Results and Suggestions (Follow-Up Tests)

During cancer treatment, patients often undergo periodic CA 19-9 tests to monitor disease progression and treatment response. The interpretation of CA 19-9 levels can be seen below:

• Increasing CA 19-9 levels: This may suggest tumor growth or treatment ineffectiveness. More diagnostic tests are usually conducted to validate these findings.
• Decreasing CA 19-9 levels: A decline in CA 19-9 levels may indicate tumor shrinkage and the treatment is effective.
• Stable CA 19-9 levels: Unchanged levels may indicate disease stability, where the condition neither improves or worsens.
• Initial decrease followed by subsequent increase: This pattern could indicate cancer recurrence or progression. Further investigations are warranted to determine the underlying cause of the elevated CA 19-9 level.

In some cases, high levels of CA 19-9 can be found in healthy individuals who do not have cancer. However, elevated levels could also signify underlying conditions such as:

• Pancreatitis (inflammation of the pancreas)
• Liver disease
• Gallstones 
• Bile duct blockages or infections
• Cystic fibrosis (a genetic disorder affecting the lungs, digestive system, and other organs)

In such cases, further evaluation is recommended to help doctors determine the underlying cause of the elevated CA 19-9 levels and to guide appropriate management. 

Consult to The Right Doctor

CA 19-9 test results can be influenced by various factors such as age, gender, medical history, and overall health status. It's essential for you to engage in discussions with their doctor or oncologist regarding the interpretation of your test results. Your doctor can tell you what your test results mean and how they relate to your medical condition or your disease.

Want to know information about the results of laboratory, radiology, and other examination results? Click here!