HER2 ISH Dual Probe Copy Number
Description
HER2 in situ hybridization (ISH) Dual Probe Copy Number is the HER2 copy number based on a dual probe test.
Reporting Results of HER2 Testing by In Situ Hybridization (dual-probe assay)
* Negative (not amplified): HER2/CEP17 ratio <2.0 AND average HER2 copy number <4.0 signals/cell
* Equivocal: HER2/CEP17 ratio <2.0 AND average HER2 copy number ≥4.0 but <6.0 signals/cell
* Positive (amplified): HER2/CEP17 ratio ≥2.0 (regardless of average HER2 copy number) or Average HER2 copy number ≥6.0 signals/cell (regardless of ratio)
Note: TP52, SMSCR and RARA are gene that are also on chromosome 17. However, they are not close to the centromere, and thus can be used to assess borderline/equivocal fish results (ratios) when the centromeric probe for chromosome 17 (CEP17) performance may be problematic. Although these may be helpful in some cases, they are not the same as the CEP17 result or the ratio determined from CEP17. There should always be a prior CEP17 result when these other results are found in the chart. If one of these tests (TP52, SMSCR, RARA, or others) are used and a dual probe copy number/ratio are documented, record that result in the appropriate data item.
* D17Z1 is the CEP17 probe used in the Vysis (Abbot) FISH kit. So, for the HER2 data items, D17Z1 and CEP17 are to be treated as the same thing.
Rationale
HER2 ISH Dual Probe Copy Number is a Registry Data Collection Variable in AJCC. It is a new data item for cases diagnosed 1/1/2018+.
Additional Info
* **Source documents:** pathology report
* **For further information,** refer to the **Breast Biomarker Reporting** cancer protocols published by the College of American Pathologists for the AJCC Staging System *Breast*
Notes
**Note 1:** This SSDI is no longer required by any of the standard setters starting with 2021 diagnoses.
* For cases diagnosed 2021+, this SSDI may be left blank
**Note 2:** Physician statement of HER2 in situ hybridization (ISH) Dual Probe Copy Number can be used to code this data item.
**Note 3:** A dual probe test will report average number or mean signals per cell for both HER2 and CEP17, the latter used as a control. Record the HER2 average number or mean signals per cells in this data item. The average number or mean signals per cells is also called the copy number.
* ***Example:***
SISH RESULTS: FINAL HER2 IN SITU HYBRIDIZATION INTERPRETATION: EQUIVOCAL, INDETERMINATE. HER2 gene copy between 4 & 6 with HER2/CEP17 ratio <2.
HER2/CEP17 RATIO: 4.26 / 3.13 = 1.36
HER-2/neu SILVER IN SITU HYBRIDIZATION (SISH)
HER-2neu gene (Inform HER2 DNA probe)
Number of tumor cell nuclei counted: 120
Number of Her-2/neu gene copies: 511
Mean HER-2/neu gene copy number: 4.26
CEP-17 SILVER IN SITU HYBRIDIZATION (SISH)
CEP-17 (Inform Chromosome 17 probe)
Number of cell nuclei counted: 60
Number of CEP-17 gene copies: 188
Mean CEP-17 gene copies/nucl: 3.13
Code Dual Probe HER2 Copy Number: 4.2
[Note: This is calculated by dividing 511 by 120]
**Note 4:** **Registrars are not to calculate the copy number.**
**Note 5:** Following ASCO-CAP guidelines, a 2+ (equivocal) finding by **immunohistochemistry (IHC)** should result in additional testing with ISH to determine gene copy number.
**Note 6:** Any type of ISH test (e.g., FISH, CISH, SISH) can be used to code this data item. Code this data item using the same report used to record information in the related data item 3854: HER2 ISH Summary.
**Note 7:** A HER2 ISH test may be called "ERBB2." ERBB2 is the standard symbol for the gene 'erb-b2 receptor tyrosine kinase 2.' An IHC test identifies the protein expressed by the gene, and an ISH test identifies the gene itself.
**Note 8:** If a HER2 ISH single probe copy number test is done, and the results are between 4 and 6 (equivocal), dual probe tests are recommended.
**Note 9:** If the test results are presented to the hundredth decimal, ignore the hundredth decimal. Do NOT round.
* ***Example:***
Reported as 4.99, code as 4.9
Default
XX.8
Metadata
SSDI 2018–2020
| Code |
Description |
| 0.0-99.9 |
Reported HER2 copy number of 0.0-99.9 |
| XX.1 |
Reported HER2 copy number of 100 or greater |
| XX.7 |
Test ordered, results not in chart |
| XX.8 |
Not applicable: Information not collected for this case
(If this item is required by your standard setter, use of code XX.8 will result in an edit error.) |
| XX.9 |
Not documented in medical record
Cannot be determined (indeterminate)
Dual probe test not done; only single probe test performed
HER2 ISH Dual Probe Copy Number not assessed or unknown if assessed |
| <BLANK> |
May be blank if diagnosis year is after 2020 |
