Positive identification of CA215 pan cancer biomarker from serum specimens of cancer patients

Background: To evaluate the clinical utility of CA215 as a pan cancer biomarker, serum levels of CA215 were determined with clinically defined serum specimens from over 500 cancer patients and compared with results obtained by other nine established cancer markers. The molecular nature of this cancer-associated antigen from selected patients' sera was determined. Methods: By using improved immunoassays, serum levels of CA215 and other known biomarkers were determined for respective positive detection rates. The molecular size of CA215 from cancer patients was determined by Western blot assay. Results: By using 0.1 AU/ml as the normal cut-off value, the positive rates of CA215 for different cancers were shown to be 52% (lung), 74% (liver), 44% (colon), 61% (esophagus), 60% (stomach), 59% (ovary), 40% (prostate), 71% (breast), 38% (kidney), 41% (pancreas), 51% (cervix), and 83% (lymphoma), respectively. Other cancer markers including AFP, CEA, CA125, CA19-9, CA15-3, Cyfra21-1, Ferritin, beta(2) microglobulin and PSA were also parallelly compared. A combination of CA215 with other tissue-associated cancer markers generally resulted in much higher cancer detection rates. CA215 detected from cancer patients was confirmed to be human immunoglobulins that contain common RP215-specific carbohydrate-associated epitope. Conclusion: Through clinical evaluations of serum specimens of various cancer patients, CA215 was confirmed to be human cancer cell-derived immunoglobulins. CA215 is apparently comparable to or better than other known biomarkers for the positive detection and monitoring of many types of human cancers.