ERBB2 (HER-2) Amplification by FISH

Performing Lab:

UCSF Clinical Cancer Genomics Lab

CPT Code:

88377

Specimen Type
Formalin-fixed, paraffin-embedded tissue on six (6) unstained slides (5 microns thick) on charged glass. One adjacent hematoxylin and eosin stained (H&E) slide should also be included. Slides should be labeled with pathology case number and block identification. Cytology smears may also be used for testing if there is sufficient tumor present. Contact the laboratory at 415.502.3252 or [email protected] if testing on a cytology smear is desired.
Methodology: Fluorescence in-situ hybridization (FISH)
Turnaround Time: 7-14 days

TEST INDICATIONS:

ERBB2 (HER-2) amplification by FISH is designed to detect amplification of the ERBB2 (Her-2/neu) gene, a genomic alteration in many tumor types. In breast, gastroesophageal, and uterine serous carcinomas, ERBB2 amplification, in combination with appropriate immunohistochemical staining, is predictive of response to Trastuzumab therapy.

HOW THE TEST WORKS:

Standard processing in 10% neutral buffered formalin was used for the tissue sample. Standard fixation in UCSF Pathology is 6-48 hours for all samples. Fixation time is unknown for samples processed in other laboratories. A histologic section from the selected tumor block was reviewed by a pathologist to evaluate tumor and normal tissue morphology, and an adjacent paraffin section was used for FISH analysis. That section was hybridized with fluorescent probes from the Vysis PathVysion (TM) HER2 DNA Probe Kit, which includes probes for centromere 17 (CEP17) and HER2. The tumor slide was denatured and subsequently allowed to hybridize with the PathVysion (TM) probes. Following hybridization, the unbound probe was removed by a series of washes, and the nuclei counterstained with DAPI (4, 6 diamidino-2-phenylindole). Enumeration of CEP17 and HER2 signals was conducted by microscopic examination of cell nuclei using a fluorescence microscope equipped with appropriate excitation and emission filters. A control slide with both tumor showing HER2 amplification and normal tissue without amplification demonstrated the appropriate signal patterns.

LIMITATIONS OF THE TEST:

ERBB2 FISH testing results should be correlated with results from immunohistochemistry staining for HER2. Depending on the tumor type, ERBB2 amplification in the absence of sufficient HER2 staining may not correlate with tumor responsiveness to trastuzumab. Specifically, gastroesophageal and uterine serous carcinomas should only be tested by FISH when immunohistochemistry shows 2+ (equivocal) staining.

The clinical interpretation of this test should be evaluated within the context of the patient's medical history, other diagnostic tests, and the histologic and immunohistochemical features of the tumor.

This test utilizes a laboratory modification of the procedure for the Vysis PathVysion (TM) HER2 DNA Probe Kit, which is FDA-approved for the detection of the Her-2/neu gene via fluorescence in situ hybridization (FISH). Modifications were validated by the UCSF Clinical Cancer Genomics Laboratory to confirm performance characteristics, in compliance with current guidelines for clinical implementation. This test has not been cleared or approved by the U.S. Food and Drug Administration. This laboratory is certified under the Clinical Laboratory Improvement Amendments of 1988 (CLIA-88) as qualified to perform high complexity clinical laboratory testing.

SPECIMEN REQUIREMENTS FOR A SUCCESSFUL TEST:

Blocks selected for ERBB2 Amplification Testing by FISH must contain tumor tissue. The assay is optimized for formalin-fixed tissue; tissue processed with other fixatives will not be rejected, but may not provide interpretable results. Decalcified specimens are usually unsuitable for FISH testing but an attempt at hybridization will be performed. An adjacent H&E-stained slide must be included. Contact the laboratory at 415.502.3252 or [email protected] if the specimen suitability is uncertain. Label slides with pathology case number and block identification.

Specimen rejection criteria include: All required slides not included. Insufficient tumor tissue present on slide as determined by pathologist. Outside slides not labeled or not accompanied by printed copy of test order.

HOW TO ORDER THE TEST:

UCSF Clinicians — this test can be ordered through Pathology
Outside Physicians — this test can be ordered with the CCGL Requisition Form

For all specimens, an interpretation of this test by a laboratory physician will automatically be performed and billed for separately.