CYFRA 21-1 is a soluble protein fragment measured in the blood. Its presence can provide insights into cellular activities and may be relevant to various health conditions.
What is CYFRA 21-1?
CYFRA 21-1 is a soluble fragment of cytokeratin 19 (CK19), a protein that helps form the internal framework, or cytoskeleton, of certain epithelial cells. Epithelial cells line the surfaces of organs and structures throughout the body, including the bronchial lining in the airways. When these cells undergo damage, rapid growth, or turnover, such as during tumor development, fragments like CYFRA 21-1 can be released into the bloodstream.
While cytokeratins are found in various body tissues, CK19, and consequently CYFRA 21-1, are particularly abundant in the lung. This makes CYFRA 21-1 a circulating marker, indicating cellular processes in specific tissues.
When is a CYFRA 21-1 Test Performed?
A doctor typically orders a CYFRA 21-1 test as a tumor marker, primarily for monitoring non-small cell lung cancer (NSCLC). This includes assessing treatment response, detecting cancer recurrence, and sometimes determining disease outlook. Decreasing levels during treatment may suggest effective therapy.
The test is not used for initial cancer screening or diagnosis. Instead, its application is in ongoing management, where changes in levels over time provide valuable information about the disease course. While most commonly associated with lung cancer, CYFRA 21-1 may also be used in monitoring other epithelial tumors, such as some urological, gastrointestinal, and gynecological cancers.
Interpreting CYFRA 21-1 Test Results
Normal CYFRA 21-1 levels are typically below 3.3 ng/mL, although this can vary slightly between laboratories. An elevated level can be associated with certain conditions, most notably specific types of non-small cell lung cancer, such as squamous cell carcinoma and adenocarcinoma. Higher levels may indicate a more advanced disease stage or a less favorable prognosis.
Elevated CYFRA 21-1 levels are not exclusive to cancer. Non-cancerous conditions, including benign respiratory diseases like pneumonia, sepsis, liver disease, and kidney failure, can also lead to increased levels. Thus, a single elevated result does not definitively mean cancer. Healthcare professionals always interpret CYFRA 21-1 results within the broader context of a patient’s health, symptoms, and other diagnostic tests, such as imaging and biopsies. For example, a combination of CYFRA 21-1 and other markers like carcinoembryonic antigen (CEA) may be used for a more comprehensive assessment in lung adenocarcinoma.
Limitations of the CYFRA 21-1 Test
The CYFRA 21-1 test is not a standalone diagnostic tool for cancer; an elevated level does not confirm cancer, and a normal level does not rule it out.
The test can yield false positive results, where levels are elevated in healthy individuals or those with non-cancerous conditions. Conversely, false negatives can occur, meaning levels remain within the normal range even when cancer is present. Factors such as kidney dysfunction can also influence results, potentially leading to higher levels. The CYFRA 21-1 test provides one piece of a larger diagnostic puzzle and is always used in conjunction with other clinical assessments, imaging studies, and tissue biopsies to form a complete picture of a patient’s health.