[Histonet] Breast Her2Neu IHC vs FISH

Wed Apr 19 15:33:19 CDT 2017

We add a comment when the specimen handling is outside of 2013 CAP/ASCO
guidelines for breast or 2016 CAP/ASCO/ASCP guidelines for HER2 testing in
GEA cancers.  These guidelines and the data supplements have some good
information.  We usually have found that decal doesn't affect the IHC much
if not excessive (but still add a comment) and we do attempt performing
FISH and have to rely internal controls (normal 2-signal pattern on
non-neoplastic cells) to know that the FISH reaction is appropriate.  FISH
working will depend on time in formalin before decal and time in decal.
This changes from specimen to specimen, so it may be difficult to validate
the full range of specimen variability.  If you do FISH, the best trick is
to re-apply the probe on the same slide that was already denatured and
hybridized the previous day and run it through denaturation and
hybridization again.  This will bring out the signals in many cases.

Since FISH has internal controls (normal 2-signal pattern in non-neoplastic
cells), it can help give some confidence to a negative HER2 IHC result when
specimen handling was compromised.  I believe that is why the CAP question
below says to perform "confirmatory analysis by in-situ hybridization".

These are some of our comments
Decal:

This assay has not been validated on decalcified tissues.  Results should
be interpreted with caution given the possibility of false negativity on
decalcified specimens.  (we don't add this comment if the result is
positive).

Formalin fixation:
The specimen did not meet optimal formalin fixation guidelines (fixed for
xxx hours).  This can play a role in loss of FISH signals.  Repeat testing
on an appropriately fixed specimen is recommended, if clinically feasible.

Fixation and decal:
The specimen did not meet optimal formalin fixation guidelines (fixed for
xxx hours and xxx minutes).  Both factors may play a role in weak or
missing FISH signals.  Repeat testing on a non-decalcified and properly
fixed specimen is recommended, if clinically feasible.

There is a CAP question that asks about some of those factors.  Not sure if
you are CAP-accredited or not.

**REVISED** 07/28/2015
ANP.22983 HER2; ER/PgR - Fixation Phase I
If the laboratory assesses HER2 protein over-expression by
immunohistochemistry, HER2
(ERBB2) gene amplification by in situ hybridization, or
estrogen/progesterone receptor
expression by immunohistochemistry, there is a written procedure to ensure
appropriate
specimen fixation time.

Anatomic Pathology Checklist 08.17.2016
NOTE: Specimens subject to these tests should be fixed in 10% neutral
buffered formalin for
at least six hours and up to 72 hours. The volume of formalin should be at
least 10 times the
volume of the specimen. Decalcification solutions with strong acids should
not be used. For
cases with negative HER2 results by IHC that were fixed outside these
limits, consideration
should be given to performing confirmatory analysis by in-situ
hybridization.
Laboratories must communicate the following fixation guidelines to clinical
services:
1. Specimens should be immersed in fixative within one hour of the biopsy
or resection
2. If delivery of a resection specimen to the pathology department is
delayed (e.g.
specimens from remote sites), the tumor should be bisected prior to
immersion in
fixative. In such cases, it is important that the surgeon ensure that the
identity of the
resection margins is retained in the bisected specimen; alternatively, the
margins
may be separately submitted.
3. The time of removal of the tissue and the time of immersion of the
tissue in fixative
should be recorded and submitted to the laboratory
Communication may be through memoranda, website, phone, face-to-face
meetings, or other
means. The laboratory should consider monitoring compliance and contacting
clients when these
guidelines are not met.
If specimens are fixed in a medium other than 10% neutral buffered
formalin, the
laboratory must perform a validation study showing that results are
concordant with
results from formalin-fixed tissues.
Laboratories testing specimens obtained from another institution should
have a policy that
addresses time of fixation. Information on time of fixation may be obtained
by appropriate
questions on the laboratory’s requisition form.
Reports should qualify any negative results for specimens not meeting the
above guidelines.
Reports containing ER, PgR or HER2 results for their predictive
characteristics must specify the
type of fixative used and the cold ischemia time. In addition, any
treatment that may potentially
alter immunoreactivity, such as decalcification, must be included.

Mark Tarango

On Wed, Apr 19, 2017 at 12:29 PM, Jason McGough via Histonet <
histonet at lists.utsouthwestern.edu> wrote:

> Does anyone know or can you point me in the right direction to some
> literature about how to properly test for Her2Neu (IHC vs. FISH) on breast
> tumors if the cold ischemia time is greater than 1 hour or if the formalin
> fixation times are outside of the recommended time range? Also, what if the
> specimen has been placed in decal? We are struggling to find any
> documentation of how to properly test Her2Neu if the specimen is outside of
> these ranges. Thanks for your help!
>
>
>
> Jason McGough, HT(ASCP)
>
> Operations Manager
>
> Clinical Laboratory of the Black Hills
>
> 605-343-2267
>
> jmcgough at clinlab.com <mailto:jmcgough at clinlab.com>
>
> www.clinlab.com <http://www.clinlab.com>
>
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