NEW YORK (Reuters Health) - Immunohistochemistry testing for HER-2 oncogene status in breast cancers correlates strongly with fluorescence in situ hybridization (FISH), physicians in Seattle report. Because FISH testing is more costly and more time consuming, they suggest that immunohistochemistry should be the method of choice, with FISH reserved for specimens with indeterminate results.
Both tests require subjective interpretation, Dr. Allen M. Gown and colleagues explain in their report, published in the Journal of the American Medical Association for April 28. The issue is controversial but important, they add, since HER-2 overexpression predicts benefit from doxorubicin-based chemotherapy and treatment with the anti-HER-2 antibody, trastuzumab.
As part of a strict quality control and quality assurance program, Dr. Gown’s team analyzed results for 2963 tissue specimens tested with both methods at PhenoPath Laboratories. Specimens came from 135 institutions in 29 states, thus representing a wide spectrum of specimen handling and tissue fixation practices.
The concordance rate between the two test methods was 64.9% when immunohistochemistry scores of 2+ and 3+ were grouped together as a positive result, the report indicates. After excluding 2+ scores, the concordance rate rose to 96.1%.
Failure to obtain interpretable results after two test runs occurred in 5.0% of samples tested by FISH and 0.08% of those tested by immunohistochemistry.
FISH is more expensive, the authors note, with reagent costs averaging $140 compared with $10 for immunohistochemistry. Procedure time and interpreting time by the pathologist are both about nine times higher for FISH.
Dr. Gown’s group recommends a testing algorithm for HER-2 determination in which primary screening is performed with immunohistochemistry. FISH would then be required for the approximately 15% of samples with indeterminate (2+) immunohistochemistry scores.
“In the HER-2 testing debate of ‘to FISH or not to FISH,’ the combined use of FISH and immunohistochemistry will achieve more accuracy and clinical efficacy than the use of either test alone,” Drs. Elizabeth L. Wiley and Leslie K. Diaz write in a related editorial.
The two pathologists at Northwestern University Medical School in Chicago agree with Dr. Gown’s group that strict adherence to quality control and quality assurance measures are required to maintain high-quality HER-2 testing using this algorithm.
Source: JAMA 2004;291:1972-1977,2019-2020. [ Google search on this article ]
MeSH Headings:Algorithms: Biochemistry: Biological Sciences: Chemistry: Chemistry, Analytical: Computing Methodologies: Cytological Techniques: Genetic Techniques: Health Occupations: Health Services Administration: Histocytochemistry: Histological Techniques: Immunochemistry: Immunohistochemistry: Immunologic Techniques: Information Science: Mathematics: Medical Informatics: Medical Informatics Computing: Investigative Techniques: Physical Sciences: Quality Assurance, Health Care: Quality Control: Quality of Health Care: Science: Technology: Technology, Industry, and Agriculture: Technology, Medical: Allied Health Occupations: In Situ Hybridization: In Situ Hybridization, Fluorescence: Health Care Quality, Access, and Evaluation: Genes, erbB-2: Genes, erbB: Cytogenetic Analysis: Analytical, Diagnostic and Therapeutic Techniques and Equipment: Biological Sciences: Health Care: Information Science: Physical Sciences: Technology, Food and BeveragesCopyright © 2002 Reuters Limited. All rights reserved. Republication or redistribution of Reuters content, including by framing or similar means, is expressly prohibited without the prior written consent of Reuters. Reuters shall not be liable for any errors or delays in the content, or for any actions taken in reliance thereon. Reuters and the Reuters sphere logo are registered trademarks and trademarks of the Reuters group of companies around the world.