Tissue polypeptide antigen (TPA) circulates in the blood as a complex of polypeptide fragments from the cytokeratin 8, 18, and 19. These three types of cytokeratin are characteristic of the inner epithelium and are widely distributed in normal tissues and in tumors derived from them. Serum levels of tissue polypeptide antigen have been shown to correlate well with cell growth rate and tumor size and are elevated in both metastatic and disseminated diseases. TPA is therefore valuable as a prognostic indicator for monitoring and treating patients with different carcinomas.
Tissue polypeptide antigen is just as good as CYFRA 21-1 in lung cancer. The overall sensitivity of TPA to the diagnosis of lung cancer, regardless of type, is approximately 70%. The sensitivity for non-small cell lung cancer (NSCLC) is about 80%. Tissue polypeptide antigen correlates well with tumor size and extent of disease and further predicts disease progression and is an early indication of relapse. Changes in TPA often precede the detection of relapses by conventional methods. Treatment response can be detected within seven days because the half-life of TFA is less than one day.
TPA together with CA 15-3 can be used to monitor breast cancer. Several studies have shown that TPA is highly sensitive to breast cancer.
Important Note
Laboratory test results are the most important parameter for the diagnosis and monitoring of all pathological conditions. 70%-80% of diagnostic decisions are based on laboratory tests. The correct interpretation of laboratory results allows a doctor to distinguish "healthy" from "diseased".
Laboratory test results should not be interpreted from the numerical result of a single analysis. Test results should be interpreted in relation to each individual case and family history, clinical findings, and the results of other laboratory tests and information. Your personal physician should explain the importance of your test results.
At Diagnostiki Athinon we answer any questions you may have about the test you perform in our laboratory and we contact your doctor to get the best possible medical care.
