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Serum protein biomarkers

Current diagnostic and follow-up serum biomarkers in clinical oncology (e.g., prostate specific antigen [PSA, prostate cancer], CA-125 [ovarian cancer]), involve identifying and quantifying specific proteins, but limitations may include non-specificity and elevation in benign conditions.

Ovarian cancer is the leading cause of death from gynecologic malignancy in the U.S., as most patients present with advanced disease with a 5-year survival rate between 15–45%. However, if the disease is caught in Stage I, survival rates are 95%. Therefore, there is great interest in a biomarker to detect ovarian cancer in its earliest stages, as current screening methods are inadequate.

Serum measurements of PSA are used as a screening method for detecting prostate cancer. Very low or very high serum PSA results are most reliable in determining cancer risk. However, values often fall within a range that is nonspecific, and thus many patients end up undergoing biopsy for benign disease. Proteomics has been proposed as a technique to further evaluate cancer risk in this diagnostic "gray" zone.

Proteomics

Proteomics involves the use of mass spectometry to study differences in patterns of protein expression. While patterns of protein expression have been proposed to yield more biologically relevant and clinically useful information than assays of single proteins, many limitations in the use of proteomics exist. (1) In contrast to genomics, where amplification techniques like polymerase chain reaction (PCR) allow for the investigation of single cells, no technology is available at the protein level. (1) Other issues between studies have been lack of uniform patient inclusion and exclusion criteria, small patient numbers, absence of standardized sample preparations and limited analytical reproducibility. (1)

Proteomic tests 

Correlogic Systems, Inc. has developed a serum-based test using proteomics for the early detection of epithelial ovarian cancer called OvaCheck®. The test is based on proteomic patterns detected in the serum, which are further analyzed with the use of a mass spectrometer to profile a population of proteins based on their size and electrical charge. This type of analysis contains thousands of data points, which undergo further sophisticated computer analysis using artificial intelligence-based algorithms to identify a pattern that is consistent with ovarian cancer.

Originally, the manufacturer had assumed that the test would not be subject to approval by the U.S. Food and Drug Administration (FDA), since the test would be performed exclusively at one reference laboratory and testing materials do not cross state lines (i.e., a "home brew" test). However, in 2004, the FDA determined that the software used to perform the analysis was considered a medical device and under the FDA premarket review jurisdiction. At this time, Correlogics is conducting clinical trials on OvaCheck® at sites in the U.S. and abroad, and it is not commercially available.

Correlogics is also in the process of developing proteomic blood tests for the detection of colorectal, breast (MammoCheck®) and prostate cancer (ProstaCheck®).

Proteomic testing is not commercially available at this time.

There is no specific code for the OvaCheck test.

9/18/2007: Policy reviewed, no changes

6/26/2009: Policy Description section changed

09/25/2012: Policy title changed from "Analysis of Proteomic Patterns in Serum to Identify Cancer" to "Analysis of Proteomic Patterns for Early Detection of Cancer." Policy statement unchanged.

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