483333: HER-2/CEP17 FISH, Breast With Reflex to Immunohistochemistry (IHC) if Group 2, 3, 4 by FISH

Test Details

Methodology

Fluorescence in situ hybridization (FISH), Immunohistochemistry (IHC)

Result Turnaround Time

3 - 5 days

Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.

Use

Tissues are evaluated for gene amplification status by FISH. Specimens demonstrating a classification of Group 2, 3, 4 by FISH are evaluated by immunohistochemistry.

Special Instructions

Direct any questions regarding this test to Oncology Customer Service at 800-345-4363.

Limitations

Use of fixatives other than 10% neutral-buffered formalin or fixation times less than six hours or more than 72 hours may not yield reliable results. Decalcification procedures may negatively affect antigenicity and DNA quality.

Use of fixatives other than 10% neutral-buffered formalin or fixation times less than six hours or more than ~~48 hours may not yield equivalent or satisfactory results~~.

Specimen Requirements

Specimen

Formalin-fixed, paraffin-embedded (FFPE) tumor

Volume

One paraffin block or seven unstained, positively-charged tissue slides cut at 4-5 microns and dried for one hour at 60°C.

Container

Paraffin block transport pouch or slide mailer

Collection Instructions

Specimen should be fixed in 10% neutral-buffered formalin. Time from tissue acquisition to fixation should be as short as possible. Fixation time should be between six and 72 hours according to ASCO/CAP guidelines.

Specimen should be fixed in 10% neutral-buffered formalin. ~~Fixation time should be between 6 and 72 hours according to ASCO/CAP guidelines; however, the package insert indicates optimum fixation time between 18 and 24 hour~~s.

Storage Instructions

Maintain specimen at room temperature.

Causes for Rejection

Tumor other than breast tumor

References

Modi S, Jacot W, Yamashita T, Petukhova MN, Agafonov SV, Itkin GP. Trastuzumab Deruxtecan in Previously Treated HER2-Low Advanced Breast Cancer. N Engl J Med. 2022 Jul 7;387(1):9-20. PubMed 35665782

PATHWAY anti-HER-2/neu (4B5) Rabbit Monoclonal Primary Antibody [package insert]. Roche Diagnostics; Jan 29, 2025.

Wolff AC, Hammond MEH, Allison KH, et al. Human Epidermal Growth Factor Receptor 2 Testing in Breast Cancer: American Society of Clinical Oncology/College of American Pathologists Clinical Practice Guideline Focused Update. J Clin Oncol. 2018 Jul 10;36(20):2105-2122. PubMed 29846122

Dybdal N, Lieberman G, Anderson S, et al. Determination of HER2 gene amplification by fluorescence in situ hybridization and concordance with the clinical trials immunohistochemical assay in women with metastatic breast cancer evaluated for treatment With trastuzumab. Breast Cancer Res Treat. 2005 Sep;93(1):3-11.16184453

Mass RD, Press MF, Anderson S, et al. Evaluation of clinical outcomes according to HER2 detection by fluorescence in situ hybridization in women with metastatic breast cancer treated with trastuzumab. Clin Breast Cancer. 2005 Aug;6(3):240- 246.16137435

Wolff AC, Hammond MEH, Allison K, et al. Human Epidermal Growth Factor Receptor 2 Testing in Breast Cancer: American Society of Clinical Oncology/College of American Pathologists Clinical Practice Guideline Focused Update. J Clin Oncol. 2018 Jul 10;36(20):2105-2122.29846122