Her2-Neu19 and 20+??

[Donna]

Hi Amazing Group,

My cousin whom I mentioned in another post has been diagnosed with almost identical breast cancer as mine had her surgery and post op visit with her Doc. She noticed a number on the pathology behind the her2-neu - it was 4 - and the Doc said that meant it is mild, that she has seen it come in as high as 19 or 20. I was under the impression you got either a 1, 2 or 3 and that was it. Can anyone give me more information on this? Did one of the two of us misunderstand?

Hve a Great Day Everyone!

Donna

[AlaskaAngel]

Hi Donna,

There are different lab tests used to test for HER2. They do measure somewhat different characteristics of HER2, and some feel the FISH is more reliable than the IHC test, but either one can be used. If one is ++ by IHC then the FISH is used to confirm or refute the IHC results. The IHC test uses +, ++, or +++ for the different scores. The FISH uses a range of actual numbers. I'd have to look up what the CISH test scores are like, but that is another test that is less often used.

AlaskaAngel

[julierene]

If I remember correctlt it was on a scale. 1-4 was +, 5-8 was ++, and 9 and up was +++. I could be way off on this. Was that pathology grade maybe?

[Grace]

Donna--she needs to ask her doctor what the "4" referred to. It might be anything, although I suspect it's the FISH score, although even there I don't know if a "4" is considered mild.

[Debra]

I would like to know the answer to this question as well for my path report said "C17 ratio" 7.46 next to the HER2 positive statement. From what I have researched, I understand that number to mean that there was 7.46 cells that "lit up" per cancer cell and frankly, I don't like that number of mine if that is the case!

[Lani]

IHC is performed by staining for a certain protein and looking at the tissue under the microscope for both the quantity of stain taken up and for certain patterns of staining (eg staining of the nucleus vs staining of the cytoplasm)

FISH detects the number of copies of the her2 gene, rather than the her2 protein.

IHC is done as a preliminary to avoid performing the more expensive and more technically demanding FISH test ie, if the staining is 0 or 1+ there is no need to proceed to the FISH test.

FISH rather than IHC is the test most indicative of response to (effectiveness of) herceptin. From the official guidelines:

Positive HER2 test. Based on a literature review of clinical trials, international studies and protocols, expert consensus, and US Food and Drug Administration Panel findings, a positive HER2 test is defined as either IHC result of 3+ cell surface protein expression (defined as uniform intense membrane staining of > 30% of invasive tumor cells) or FISH result of amplified HER2 gene copy number (average of > six gene copies/nucleus for test systems without internal control probe) or HER2/CEP 17 ratio of more than 2.2, where CEP 17 is a centromeric probe for chromosome 17 on which the HER2 gene resides. The 30% criteria for a positive IHC is further discussed in Appendix G. The original FISH test results were defined as either positive or negative, but an intermediate range (from hereon referred to as equivocal range) has since been described and the clinical significance of this observation remains unclear.34-36 This strategy classifies patients as having HER2-positive disease based on positive results with either test. It is recognized that current data are insufficient to define whether these patients represent true- or false-positives. Although the large prospective randomized clinical trials of trastuzumab were not prospectively designed to answer these questions, we anticipate and recommend that such analyses will be forthcoming as correlative studies.

Equivocal HER2 test. Much of the confusion about HER2 testing has resulted from the need to define trastuzumab treatment (yes or no) based on test results that represent a continuous rather than a categoric variable. Furthermore, there is significant variation in the intermediate (equivocal) ranges for both the IHC and FISH assays. The equivocal range for IHC consists of samples scored 2+, and this may include up to 15% of samples.29 An equivocal result (2+) is complete membrane staining that is either nonuniform or weak in intensity but with obvious circumferential distribution in at least 10% of cells. Very rarely, in the experience of panel members, invasive tumors can show intense, complete membrane staining of 30% or fewer tumor cells. These are also considered to be equivocal in this guideline. Some but not all of these samples may have HER2 gene amplification and require additional testing to define the true HER2 status (Figs 1 and 2).54,55

The equivocal range for FISH assays is defined as HER2/CEP 17 ratios from 1.8 to 2.2 or average gene copy numbers between 4.0 and 6.0 for those systems without an internal control probe.34-36 Note, however, that patients with a HER2/CEP17 FISH ratio between 2.0 and 2.2 were formerly considered HER2-positive and were eligible for treatment in the adjuvant trastuzumab trials. Therefore, available efficacy data do not support excluding them from therapy with trastuzumab. This group is much smaller, probably fewer than 3% of samples.56 Polysomy 17 is observed in approximately 8% of all specimens, mostly among cases with four to six HER2 gene copies (equivocal range).57,58 There is no accepted definition of what constitutes polysomy and authors have used different criteria to define it. If polysomy 17 is defined as three or more copies of CEP17, most are not associated with protein or mRNA overexpression57 and the same has been observed in tumors with a HER2 gene copy number between 4 and 6.35

Discordant results (IHC 3+/FISH-negative or IHC < 3+/FISH-positive) have also been described, and were observed in approximately 4% among 1,503 patients screened centrally (LabCorp, Burlington, NC) with both methods for eligibility for a clinical trial with trastuzumab.59 However, clinical outcome data for these two groups are not yet available. We anticipate and recommend that such analyses will be forthcoming as correlative studies of the large prospective randomized clinical trials of trastuzumab.

It is also clear from the panel discussion and literature review that patients with equivocal HER2 test results constitute a poorly studied subgroup with uncertain association of test scores to benefit from HER2-directed therapy.60 The panel suggested that further studies of this patient group would be promoted by defining these test results as equivocal or borderline. The panel elected to use the term equivocal to avoid confusion with borderline positive and borderline negative terminology which is sometimes used in the interpretation of FISH assays. Equivocal results of a single test require additional action which should be specified in the initial report. Equivocal IHC samples must be confirmed by FISH analysis of the sample. Equivocal FISH samples are confirmed by counting additional cells or repeating the FISH test. If FISH remains equivocal after additional cells counted or assay repeated, confirmatory IHC is recommended so that HER2 protein expression is known for the sample with true equivocal gene amplification status.

[Lani]

found this:
Level of HER-2 gene Amplification and
Response to Trastuzumab
An IHC score of 2+is considered to be border-
line or uncertain. Whether such a category exists
for FISH should also be examined. In fact, some
authors show low-level amplification by FISH,
although the definition of low-level amplification is
undetermined and various values (2.0 to 2.5, 2.0 to
less than 3.0, and 2.0 to 6.0) of the HER-2/CEP17
ratio have been reported. Owens et al. reported
that the ratios of HER-2 gene amplification in cas-
es IHC scores 0, 1+, 2+, and 3+were 4.1, 7.4,
23.3, and 91.7%, respectively, in a large cohort of
breast cancer specimens (n=6,556) submitted to
the IMPATH laboratories for HER-2 evaluation by
IHC and FISH38). In 326 tumors with low-level
amplification (HER-2/CEP17 ratio 2.0 to 2.5), only
23 (7.6%) had IHC scores of 3+, while the other
303 had IHC scores of 0, 1+, or 2+(0 in 30 tum-
ors, 1+in 64, and 2+in 209). In contrast, in 1,221
tumors with high-level amplification (HER-2/
CEP17 ratio>2.5), 625 (51.2%) had IHC scores of
3+, 527 (43.1%) had IHC scores of 2+, and the
remaining 69 (5.7%) had scores of 0 or 1+. Based
on these results, the researchers proposed that
the criteria for gene amplification should be a
HER-2/CEP17 ratio greater than 2.538). In our
study, five out of six cases with low-level HER-2
amplification (HER-2/CEP17 ratio between 2.0 and
3.0) had HER-2 IHC scores of 0 or 1+, whereas 33
of 34 cases with higher-level HER-2 amplification
(3.0 fold or higher) had an IHC score of 3+36). As
shown above, Press et al. demonstrated that bre-
ast cancers with a HER-2/CEP17 ratio of 2.0 to 6.0
were frequently responsive to trastuzumab39). At
present, it is unknown whether borderline amplifi-
cation (HER-2/CEP17 ratio 2.0 to 2.5) is correlat-
ed with sensitivity to trastuzumab.

Hope this helps!

PS I have been trying to collect information on familial her2+ breast cancer.

I have posted an article about it previously. Once all the path is back, could you post your (and your cousin's) particulars ie, size of tumor, lymph node involvement, grade, stage, ER %, PR%, Ki-67, her2 by IHC (ie, 0,1,2,or 3+), her2 FISH value, whether there was adjacent DCIS or LCIS, etc.

If you utilize the search and cannot find the article I previously posted (authors from Spain) let me know and I will post it again.

THANKS

[Lani]

IHC FISH negative (Her-2/chr 17 ratio < 2.0)
FISH positive (Her-2/chr 17 ratio 2.0)
N Chr 17 copy number (range) Her-2 copy number (range) N Chr 17 copy number (range) Her-2 copy number (range)
0 202 1.67 (1.03–4.28) 1.87 (1.04–4.71) 2 1.60 (1.44–1.77) 6.46 (4.25–8.67)
1+ 166 1.67 (1.15–3.20) 1.98 (1.10–4.94) 4 2.57 (1.96–3.44) 9.21 (3.92–14.1)
2+ 43 1.75 (1.00–3.00) 2.19 (1.00–3.86) 20 1.95 (1.03–3.38) 6.87 (2.07–20.4)
3+ 15 2.45 (1.85–3.69) 3.19 (1.85–5.21) 109 2.33 (1.07–4.96) 11.0 (3.21–40.7)
Total 426 1.70 (1.00–4.28) 135 2.27 (1.03–4.96)

The first set are are chromosome 17 copy number for FISH negative tumors, the second set are her2 copy numbers for FISH negative tumors, the third set of numbers are the chromosome 17 copy numbers for FISH positive tumors and the fourth set of numbers are her2copy numbers for FISH positive tumors. Thus, if your cousin is FISH positive and IHC 3+ the range of Chromosome 17 copies would be from 1-4.96, if she is IHC3+ and FISH positive, the range of her2 copies could potentially be from 3.21 to 40 (I assume if the number you have provided is a her2 copy number than she would not likely be IHC 2+. THERE IS ALSO THE POSSIBILITY THAT THE OTHER NUMBERS STAND FOR EXCESS OR DELETED PORTIONS OF CHROMOSOMES, BUT THEY USUALLY HAVE A NUMBER WITH A SMALL LETTER BEHIND THEM IE, 17q- etc.

As her2 FISH is often reported as a ratio and there are some technicalities regarding chromosome 17 that can alter the FISH results, it is best to try to have the pathology report explained in detail to you/your cousin.

Again, I hope some of this helped.