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Medical Policy: 02.04.23
Original Effective Date: July 2009
Reviewed: August 2011
Revised:
Benefit Application
Benefit determinations are based on the applicable contract language in effect at the time the
services were rendered. Exclusions, limitations or exceptions may apply. Benefits may vary
based on contract, and individual member benefits must be verified. Wellmark determines medical
necessity only if the benefit exists and no contract exclusions are applicable. This medical
policy may not apply to FEP. Benefits are determined by the Federal Employee Program.
This Medical Policy document describes the status of medical technology at the time the document
was developed. Since that time, new technology may have emerged or new medical literature may
have been published. This Medical Policy will be reviewed regularly and be updated as scientific
and medical literature becomes available.
Description:
Cancers of unknown primary, or occult primary malignancies, are tumors that have metastasized from an unknown primary site, and constitute 2%-6% of all cancer cases in the United States.
Most cancers of unknown primaries are adenocarcinomas or undifferentiated tumors; less commonly they may be squamous carcinomas, melanoma, sarcoma, or neuroendocrine tumors. The most common sites of cancers of unknown primary are lung and pancreas, followed by colon, stomach, breast, ovary and prostate. Conventional methods used to aid in the identification of the origin of a cancer of unknown primary include a thorough history and physical examination, computed tomography (CT) scans of the chest, abdomen, and pelvis; routine laboratory studies; and targeted evaluation of specific signs and symptoms.
The Pathwork® Tissue of Origin Test (Pathwork Diagnostics, Inc, Redwood City, California) is a gene-expression, microarray-based test which the manufacturer claims may be useful in identifying the origin of cancers of unknown primary. The test measures the expression of more than 1500 genes and compares the similarity of the gene expression profile of a cancer of unknown primary to a database of known profiles from 15 tissues with more than 60 histologic morphologies. The test uses a proprietary Pathchip® microarray and runs on the Affymetrix GeneChip® system. The report generated for each tumor consists of a “similarity score,” which is a measure of similarity of the gene expression profile of the specimen to the profile of the 15 known tumors in the database. Scores range from 0 (very low similarity) to 100 (very high similarity), and sum to 100 across all 15 tissues on the panel. If a single similarity score is greater than or equal to 30, it indicates that this is likely the tissue of origin. If every similarity score is between 5 and 30, the test result is considered indeterminate, and a similarity score of less than 5 rules out that tissue type as the likely origin.
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Prior Approval:
Not applicable
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Policy:
Microarray-based gene expression testing to evaluate the site of origin of a tumor of unknown primary is considered investigational.
Microarray-based gene expression testing to distinguish a primary from a metastatic tumor is considered investigational.
The Pathwork® Tissue of Origin test has not been FDA-approved for use in cancer of unknown origin, nor has it been approved for differentiating metastatic from primary cancers. In addition, there have been no new data published that would provide direct evidence of the clinical utility of the Pathwork® test, nor has the clinical application of gene expression profiling to direct patient management and tumor site-specific therapy been demonstrated in prospective studies. Without knowledge of how this test would affect clinical practice and clinical health outcomes for patients diagnosed though its use , the test is considered investigational.
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Procedure Codes and Billing Guidelines:
- To report provider services, use appropriate CPT* codes, Modifiers, Alpha Numeric (HCPCS level 2) codes, Revenue codes, and/or ICD-9-CM diagnostic codes.
There is no specific code to report this type of testing. It is likely that a variety of CPT codes will be used that describe each step of the process, i.e., sample preparation followed by microscopic analysis. The coding most likely would include codes from the molecular diagnostic section of CPT 83890-93913 and should include the appendage of modifier 0Z. This modifier indicates genetic testing for a solid tumor gene, not otherwise specified.
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Selected References:
- Dumur EI, Lyons-Weiler M, Sciulli C et al. Interlaboratory performance of a microarray-based gene expression test to determine tissue of origin in poorly differentiated and undifferentiated cancers. J Mol Diagn 2008. 10(1):67-77.
- Monzon FA, Lyons-Weiler M, Buturovic LJ et al. Multicenter validation of a 1,550-gene expression profile for identification of tumor tissue of origin. J Clin Oncol.2008;27(15):2503-08.
- Stancel GA, Coffey D, Alvarez K et al. Identification of tissue of origin in body fluid specimens using a gene expression microarray assay. Cancer Cytopathol. 2011 Jun 29. doi: 10.1002/cncy.20167. [Epub ahead of print].
- Beck AH, Rodriguez-Paris J, Zehnder J et al. Evaluation of a gene expression microarray-based assay to determine tissue type of origin on a diverse set of 49 malignancies. Am J Surg Pathol. 2011 Jul;35(7):1030-7.
- Grenert JP, Smith A, Ruan W et al. Gene expression profiling from formalin-fixed, paraffin-embedded tissue for tumor diagnosis. Clin Chim Acta. 2011 Jul 15;412(15-16):1462-4. Epub 2011 Apr 7.
- Pillai R, Deeter R, Rigl CT. Validation and reproducibility of a microarray-based gene expression test for tumor identification in formalin-fixed, paraffin-embedded specimens. J Mol Diagn. 2011 Jan;13(1):48-56. Epub 2010 Dec 23.
- Wu AH, Drees JC, Wang H et al. Gene expression profiles help identify the tissue of origin for metastatic brain cancers. Diagn Pathol. 2010 Apr 26;5:26.
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Policy History:
Date Reason Action
August 2011 Annual review Policy renewed
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Wellmark medical policies address the complex issue
of technology assessment of new and emerging treatments, devices,
drugs, etc. They are developed to
assist in administering plan benefits and constitute neither offers of
coverage nor medical advice. Wellmark medical policies contain only a
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constitute a contract. Wellmark does not provide health care services
and, therefore, cannot guarantee any results or outcomes.
Participating providers are independent contractors in private
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affiliates. Treating providers are solely responsible for medical
advice and treatment of members. Our medical policies may be updated
and therefore are subject to change without notice.
*Current Procedural Terminology © 2010 American Medical Association. All Rights Reserved.
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